a mesophile is an organism that grows best in moderate temperature , neither too hot nor too cold , typically between 20 and 45 °c ( 68 and 113 °f ) .

the optimal temperature is 37 °c .

organisms that prefer extreme environments are known as extremophiles .

mesophiles have diverse classifications , belonging to two domains : bacteria , archaea , and to kingdom fungi of domain eucarya .

mesophiles belonging to the domain bacteria can either be gram-positive or gram-negative .

gram-positive bacteria have a cell layer made of peptidoglycan and stains purple .

gram-negative bacteria also contains peptidoglycan , yet the layer is extremely thin and stains red or pink .

oxygen requirements for mesophiles are not just confined to aerobic or anaerobic .

there are three basic shapes of mesophiles : coccus , bacillus , and spiral .

mesophile

the following semi - deciduous elements were combined : typical mesophile , fluxuating humid mesophile , notophile , and microphile forests .
vibrational entropy differences between mesophile and thermophile proteins and their use in protein engineering .
mesophile versus thermophile : insights into the structural mechanisms of kinetic stability . - pubmed - ncbi
vibrational entropy differences between mesophile and thermophile proteins and their use in protein engineering . - pubmed - ncbi
[ research on listeria sp . , salmonella sp . , staphylococcus aureus and mesophile aerobian bacteria in milk ]
the following perennial tropical forest latifoliate elements were combined : low altitude pluvial , submontane pluvial , montane pluvial , typical cloud , low cloud over serpentine , low altitude evergreen mesophile , submontane evergreen mesophile , and coastal microphile .
in some embodiments , the argonaute comprises at least 30 % amino acid identity to an argonaute from a mesophile .
[ research on listeria sp . , salmonella sp . , staphylococcus aureus and mesophile aerobian bacteria in milk ]
[ research on listeria sp . , salmonella sp . , staphylococcus aureus and mesophile aerobian bacteria in milk ] [ 1999 ]
online ) , meaning that a mesophile–thermophile species pair with no difference in genomic gc content would be expected to have significant asymmetry . the intercept of each logistic regression was used to estimate the substitutional asymmetry predicted for a mesophile–thermophile pair with no difference in gc content (
the researchers will look at ak in two bacteria : a thermophile ( thermus thermophilus ) and a mesophile ( e . coli ) .
ribosomes and ribosomal subunits from the thermophile penicillium duponti were found to be more thermostable than the corresponding particles from the mesophile penicillium notatum .
yes it is a mesophile . s . aureus grows best at around 37 degrees celsius which is the temperature of blood in the body .
c ) mesophile mesophiles grow well at body temp and streptococcus mutans has a high affinity for heart valves and joints in the human body .
what made you want to look up mesophile ? please tell us where you read or heard it ( including the quote , if possible ) .
located between northern and southern deserts of asia , kopet dag mountains could house relic mesophile flora and fauna which could not survive aridization of adjacent lowlands .
) ; at the time the database was searched , there were no other mesophile–thermophile species pairs with published genomes that were phylogenetically independent of the nine used here .
the dissociation of the 80 - s ribosomes into 60 - s and 40 - s subunits occurred at higher magnesium ion concentrations for the mesophile than the thermophile .
shows an example of this ; the proportion of h ↔ y sites with h in the mesophile and y in the thermophile decreases for species pairs in which the thermophile has greater gc than the mesophile . of the 37 amino acid pairs with no difference in average gc content of their codons , 15 have a significant slope .
- bacterium - gram negative - peritrichous - some strains are harmless - some cause e . coli 0157 : h7 - stores glycogen - mesophile - chemoorganoheterotroph - facultative anaerobe
a mesophile is an organism that grows best in moderate temperature , neither too hot nor too cold , typically between 20°c and 45°c ( 68 and 113 °f ) . the term is mainly applied to microorganisms . the habitats of these organisms include especially human body , cheese , yogurt , and mesophile organisms are often included in the process of beer and wine making .
mesophile aroma culture type b is a species of mesophilic culture that is used in making soft cheese , buttermilk , sour cream and cultred butters . ( 10 grams ) 100 gram bottle available .
of the 122 pairs of amino acids with differing average gc content and significant slopes , 114 are in the expected direction : sites with the gc - rich amino acid in the mesophile and the gc - poor amino acid in the thermophile become less common in the species pairs where the thermophile has higher genome - wide gc content than the mesophile ( supplementary table 2 , supplementary material online ) . seven of the eight pairs of amino acids that show the opposite pattern involve methionine . sites with aspartic acid , cysteine , glutamic acid , glutamine , leucine , serine , or threonine in the mesophile and methionine in the thermophile become more common as the thermophile–mesophile gc difference increases , even though the methionine codon has a slightly smaller gc content than the codons for the other amino acids .
] ) to obtain mesophilic structure neighbors with rmsd no greater than about 4 å with respect to the thermophile where the structural alignment included ~ 80 % or more of each structure , and where the thermophile and mesophile had identical or close ec numbers or functional annotation . in some cases , more than one mesophile per thermophilic protein was kept . when multiple mesophilic analogs to a single thermophilic protein were included in the
we recently introduced encom , an elastic network atomic contact model , as the first coarse - grained normal mode analysis method that accounts for the nature of amino acids and can predict the effect of mutations on thermostability based on changes vibrational entropy . in this proof - of - concept article , we use pairs of mesophile and thermophile homolog proteins with identical structures to determine if a measure of vibrational entropy based on normal mode analysis can discriminate thermophile from mesophile proteins . we observe that in around 60 % of cases , thermophile proteins are more rigid at equivalent temperatures than their mesophile counterpart and this difference can guide the design of proteins to increase their thermostability through series of mutations . we observe that mutations separating thermophile proteins from their mesophile orthologs contribute independently to a decrease in vibrational entropy and discuss the application and implications of this methodology to protein engineering .
. —the number is the predicted proportion of sites with the first amino acid in the mesophile and the second amino acid in the thermophile ; an asterisk indicates that the proportion is significantly different from 0 . 50 (
the method according to the invention concerns an anaerobic conversion of biomass into biogas in separated processes of hydrolysis and methane fermentation of biomass by means of methane mesophile , thermophile and psychrophile bacteria , contained in returned reflux .
. —average asymmetry is the predicted proportion , in a pair of species with equal gc contents , of substitutions from other amino acids in the mesophile to the given amino acid in the thermophile . transfer free energy is from
each of the nine mesophile–thermophile species pairs exhibits a large amount of substitutional asymmetry ; for most pairs of amino acids , there are more homologous sites with one amino acid in the mesophile and the other amino acid in the thermophile than the opposite . substitutional asymmetry has been previously observed in small numbers of proteins from methanococcus versus methanocaldococcus ( haney et al . 1999 ; mcdonald et al . 1999 ) , bacillus versus geobacillus ( mcdonald et al . 1999 ) , and deinococcus versus thermus ( mcdonald 2001 ) . here , i use translated protein sequences from the entire genomes of these species pairs and add six additional mesophile–thermophile pairs from a broad variety of habitats .
, greater than or equal to 50 °c ) with complete , published genome sequences . species from higher taxa in which all species with published genomes are thermophiles , such as aquificae and crenarchaeota , were excluded . the closest mesophile (
what does the term mesophile mean ? a ) mesophiles grow well at 85 degrees celsius . b ) mesophiles grow well at refrigerator temperatures . c ) mesophiles grow well at 55 degrees celsius . d ) mesophiles grow well at body temperature .
being a mesophile , staphylococcus can carry out metabolism under normal room temperature . together with the abundance of warm - blooded animals which act as hosts to provide a salty medium , it can be said that staphylococcus has an environmental implication of ubiquity .
) was used to perform logistic regression for each pair of amino acids , with the difference in genomic gc content between the thermophile and the mesophile as the independent variable and the proportion of substitutions in one direction as the dependent variable . logistic regression (
mesophiles are microorganisms which grow best in moderate temperatures . they cannot live in extreme temperature conditions ( excessive coldness or excessive heat ) . their temperature range lies between 20 0 c to 45 0 c . the optimum temperature of a mesophile is 37 0 c .
substitutional asymmetry ( proportion of all a ↔ b sites that have a in the mesophile and b in the thermophile ) versus the difference in transfer free energy of the amino acids ( b - a ) , where b is the amino acid with greater transfer free energy .
e . coli is a mesophile that grows best at 37 degrees celsius in neutral ph environments . e . coli is a facultative aerobe and is able to grow without oxygen , but it can extract more energy from its nutrient source and grow faster if oxygen is present .
substitutional asymmetry in one mesophile–thermophile pair could be caused by any number of habitat differences ; for example , the mesophile methanococcus maripaludis was isolated from a salt marsh ( jones , paynter , and gupta 1983 ) , whereas the thermophile m . jannaschii was originally isolated from a deep - sea vent 2 , 600 m below the ocean surface ( jones , leigh , et al . 1983 ) . a difference in hydrostatic pressure may favor some amino acids over others ( di giulio 2005 ) ; if hydrostatic pressure were an important selective factor , m . maripaludis and m . jannaschii would have patterns of asymmetry different from the other mesophile–thermophile pairs , which do not differ in the hydrostatic pressure of their habitats . the consistency of the patterns of asymmetry across species pairs suggests that much of the asymmetry results from selection caused by the different habitat temperatures .
a table showing the discriminatory power of sequence and structure based indices - the fraction of thermophile / mesophile pairs for which the quantity was systematically higher or lower by any amount . the contact network quantities are described in the introduction . the four body threading contact potentials are described in [
1 . “classification of microorganisms by growth temperature – boundless open textbook . ” boundless . boundless , 26 may 2016 . web . available here . 12 june 2017 . 2 . “mesophile . ” wikipedia . wikimedia foundation , 10 june 2017 . web . available here . 12 june 2017 .
) . the average of the 19 intercepts for each amino acid gives a measure of how strongly that amino acid is preferred in mesophiles or thermophiles ; for example , only 41 . 6 % of the substitutions involving serine would have serine in the thermophile and some other amino acid in the mesophile (
your supervisor asks you to set up a pure culture of a bacterial species he is researching . he tells you that this species is a fastidious , halophilic , gram - positive mesophile that does not have catalase or superoxide dismutase . what type of culture medium and environmental factors must you use to grow this organism ?
the ce structural alignment of 1aisa , a tata - box - binding protein from the extreme thermophile pyrococcus woesi , in red and 1ytba , a tata - box - binding protein from the mesophile saccharomyces cerevisiae , in blue . the rmsd is 2å and sequence identity is 40 % . clearly these are very similar structures .
in terms of thermal requirement , staphylococcus is a mesophile . regarding ph requirements , it is a neutrophile . being a facultative anaerobe , staphylococcus is catalase positive . the absence of flagella indicates that staphylococcus is a non - motile bacterium . in addition , staphylococcus aureus is coagulase positive but not for other species in the genus .
a second form of evidence used to compare amino acid composition in mesophiles and thermophiles is substitutional asymmetry ( argos et al . 1979 ; haney et al . 1999 ; mcdonald et al . 1999 ) . protein sequences from one mesophile and one thermophile are aligned , and the observation of more aligned sites with amino acid a in the mesophile and b in the thermophile than the opposite pattern provides evidence that b is favored over a in the higher temperature organism . because only aligned sites in homologous proteins are considered , the effect of gain or loss of proteins of different amino acid composition does not obscure the results . in addition , each mesophile–thermophile pair of species can be phylogenetically independent of others that have been compared , an important consideration when using comparative methods to infer adaptation . ( to say that mesophile–thermophile pair a and b are “phylogenetically independent” of other pairs means that a and b are more closely related to each other than either is to any of the other species in the data set . ) this approach has found extensive evidence for substitutional asymmetry ( haney et al . 1999 ; mcdonald et al . 1999 ; mcdonald 2001 ; nishio et al . 2003 ; mizuguchi et al . 2007 ) , but the problem remains that for those pairs of amino acids whose codons have different gc content , overall differences in gc content between the mesophile and thermophile could still be the cause of substitutional asymmetry . here , i use logistic regression of the proportion of substitutions in one direction versus the overall difference in gc content to predict the substitutional asymmetry in a pair of species with identical genomic gc content . this method should help determine whether amino acids that are favored at higher temperatures share biochemical properties .
2006 ) and endangered in luxembourg ( colling 2005 ) , and early warnings have been issued in germany due to population declines ( v : vorwarnliste , bestände zurückgehend ; 1996 assessment ) ( bundesamt für naturschutz 2012 ) . the mesophile grassland habitat is protected in the habitats directive 92 / 43 / eec ( council of the european communities 1992 ) .
we have systematically tested a large number of sequence and structure derived quantities for their ability to discriminate thermostable proteins from their non - thermostable orthologs using sets of mesophile - thermophile ortholog pairs . most of the quantities tested correspond to properties previously reported to be associated with thermostability . many of the structure related properties were derived from the delaunay tessellation of protein structures .
heatmap of average δ s vib for pair - wise amino acid substitutions from mesophile to thermophile proteins . the top right half matrix around the inverse diagonal represent for the most part mutations that increase the stability of the thermophile protein . missing values represent pairwise amino acid substitutions without statistically significant results . δ s vib values are scaled by 10 3 for visualization purposes .
secondly , it can be classified by in terms of morphology and some of the physiological characteristics . its morphology is gram positive cocci bacteria growing in clusters . it is a mesophile , nuetrophile and facultative anaerobe . it is catalase positive and only staphylococcus aureus is coagulase positive . the energy , electron and carbon sources of staphylococcus aureus can be described as chemoorganotrophic heterotrophic .
it is possible to accurately discriminate ( hyper ) thermophilic proteins from their mesophilic counterparts based on sequence and structural properties . sequence based indices used to discriminate entire proteomes also work well on individual thermophile / mesophile ortholog pairs . purely structure - based indices are , generally speaking , poor discriminators . combined sequence structure indices like the threading potential are somewhat better than sequence alone .
e . coli can grow both aerobically and anaerobically . it can synthesize all its own amino acids , purines and pyrimidines using the nitrogen donor molecule glutamine ( berks , 2002 ) . e . coli is a mesophile , which lives in the temperature range near that of humans , with a growth optimum between 25°c and 40°c ( madigan , 2002 ) . . . .
the mesophile e . coli pol i and its klenow fragment ( jacobsen , 1974 ; kornberg and baker , 1992 ) were used in the pcr reaction before the introduction of thermostable dna polymerases . these enzymes are less useful in routine pcr application , as they are heat labile , which means that fresh aliquots of the enzyme have to be added at each pcr cycle .
mean of the 19 residuals ( differences between the observed number of substitutions and that expected from the logistic regression ) for each amino acid in each species pair . values above 0 indicate that sites with that amino acid in the thermophile and other amino acids in the mesophile are more common than expected from the logistic regression of all species . error bars are 95 % confidence intervals .
average δ s vib z - scores for rubredoxin homologs . the mesophile homologs from c . pasteurianum ( pdb id 1iro ) , d . vulgaris ( pdb id 8rxn ) , and d . gigas ( pdb id 1rdg ) in blue are compared with that of the thermophile p . furiosus ( pdb id 1caa ) in red . bootstrapped differences are statistically significant with p - value < 0 . 001 .
, the difference in gc content between two species . the significance of the slope was used to test whether there was a significant relationship between the difference in gc content and the pattern of asymmetry . the significance of the intercept was used to test whether the predicted asymmetry for a mesophile–thermophile pair with equal gc contents was significantly different from the 1 : 1 ratio expected under the neutral model of molecular evolution .
mesophile and xero - acidocline hems of carpinion and fagion woods , developed on deeper soil than those of unit e5 . 21 , or on siliceous substrates , with trifolium medium , trifolium ochroleucon , brachypodium sylvaticum , digitalis grandiflora , peucedanum cervaria , campanula baumgartenii , origanum vulgare , melampyrum spp . , valeriana wallrothii , agrimonia eupatoria , vicia spp . , lathyrus latifolius and teucrium scorodonia . alliances trifolion medii , melampyrion pratensis .
reference ( s ) : 1 pankowski , j . a . , puckett , s . m . , & nano , f . e . ( 15 march 2016 ) .
temperature sensitivity conferred by liga alleles from psychrophilic bacteria upon substitution in mesophilic bacteria and a yeast species
. applied and environmental microbiology . 82 ( 6 ) : 1924–1932 . 2 mesophile . wikipedia . org . retrieved from [ [ 1 ] ] .
example of logistic regression of substitutional asymmetry and difference in gc content . gc therm − gc meso , the percent difference in gc content between the thermophile and the mesophile in each species pair . h meso → y thermo , the proportion of sites in each species pair that have histidine in the mesophile and tyrosine in the thermophile , as a proportion of all aligned sites that have histidine in one species and tyrosine in the other . error bars are 95 % confidence intervals of the binomial proportion . the solid line is the logistic regression line , given by solving ln [ y / ( 1 − y ) ] = a + bx for y , where y is h meso → y thermo , x is gc therm − gc meso , a is the intercept , and b is the slope . the dashed line shows the estimation of the expected asymmetry in a species pair with zero difference in gc content .
≤ 40 °c ) with a complete published genome sequence was identified for each thermophile using published phylogenies . where a thermophile had more than one mesophile that was equally closely related or vice versa , the species pair was chosen with the most similar habitat , physiology , and genomic gc content . where more than one strain of a species had been sequenced , the strain with the earliest published sequence was used . nine phylogenetically independent pairs of mesophiles with thermophiles were identified (
to identify amino acids that deviated from the overall pattern in particular species pairs , the residual ( difference between the observed proportion of substitutions in one direction and the proportion predicted by the logistic regression model ) was calculated for each amino acid pair in each species pair and then averaged across the 19 pairs involving each amino acid . for this analysis , the proportion of sites with the target amino acid in the thermophile and the other amino acid in the mesophile was used .
a mesophile is an organism that grows at moderate temperatures . it is different from a thermophile , which is capable of living at temperature as high as 80°c and above . mesophiles grow best at moderate temperatures , i . e . 20 and 45 °c , which are not too hot and not too cold . the term mesophile generally applies to microorganisms . bacteria , in particular , may be classified into thermophilic , mesophilic , and psychrophilic . as noted earlier , the thermophilic bacteria are active when the temperature is relatively high . psychrophilic bacteria , in contrast , are active when the temperature is relatively low . the differing optimal temperature in these bacteria is dependent upon the bacterial expression of certain alleles resulting in the production of enzymes that function at particular temperatures . one such example is a study on mesophilic and psychrophilic bacteria . accordingly , modification of genetic elements in mesophilic bacteria resulted in the changing of their temperature range to closely match that of the psychrophilic bacteria . 1
) . however , differences in transfer free energy do not explain all the substitutional asymmetry . of 139 pairs of amino acids with a significant intercept in the logistic regression ( meaning that the substitutional asymmetry is predicted to be significant for a mesophile–thermophile pair with no difference in genome - wide gc content ) , 14 have the opposite pattern : the amino acid with lower transfer free energy is found more often at higher temperatures . the next strongest associations are with several other measures of hydrophobicity (
for seven of the mesophile–thermophile pair of species , the entrez gene plot function ( urltoken ) was used to obtain a list of reciprocal best matches of protein sequences . each list was sorted , and where a sequence from one species had multiple best matches from the other species ( which can happen when there are multiple identical protein sequences ) , all but one of the matching pairs were deleted . proteins encoded by small extrachromosomal elements in methanocaldococcus jannaschii or plasmids in the other species were deleted .
mutational pathway for mesophile rubredoxin homologs to reach the thermophile sequence . three pathways are presented , the best and worst pathways according to the δ s vib contributions of single mutations and the most probable ( see methods ) . each point from right to left represents a new structure with one extra mutation toward the thermophile protein . a : c . pasteurianum ( pdb id 1iro ) , ( b ) d . gigas ( pdb id 1rdg ) , and ( c ) d . vulgaris ( pdb id 8rxn ) .
here , logistic regression modeling is used to control statistically for the effects of differing gc content , with the difference in gc content as the independent variable and the direction of substitution as the dependent variable . for the majority of amino acid pairs , the logistic regression predicts that a mesophile–thermophile pair of species that did not differ in gc content would exhibit extensive substitutional asymmetry . the significant intercepts in the logistic regression models mean that the preferences for one amino acid over another are fairly consistent across the nine pairs of species .
were constructed to contain pairs of high quality x - ray structures with high structural and functional similarity that differ only in that one is mesophilic and the other thermophilic or hyperthermophilic . they were assembled by compiling all pdb x - ray structures from a large list of organisms categorized as mesophile , thermophile or hyperthermophile using ogt’s obtained from the atcc website urltoken all structures with missing cα coordinates , insertion codes , or alternate atoms were then eliminated . the resulting two lists of thermophilic and hyperthermophilic proteins were submitted separately to pisces [
if substitutional asymmetry between mesophilic and thermophilic proteins results from temperature adaptation based on the fundamental biochemical properties of the amino acids , the same patterns should be found in all mesophile–thermophile comparisons after controlling for differences in gc content . differences in other aspects of the environment , such as salinity , hydrostatic pressure , ph , oxygen , and nutrient source , could cause patterns of asymmetry that are unrelated to temperature and therefore different in different mesophile–thermophile pairs . in addition , biosynthetic costs of amino acids are high enough to cause selection on amino acid usage ( akashi and gojobori 2002 ; seligmann 2003 ; heizer et al . 2006 ; swire 2007 ) , so organisms which differ in biosynthetic pathways , or which differ in whether they are autotrophic or heterotrophic for a particular amino acid , may have different patterns of substitutional asymmetry . a second goal of this paper is to see how consistent the patterns of substitutional asymmetry are among different species , which may help determine how much of the asymmetry is due to temperature adaptation and how much is due to other factors .
we have defined discriminatory power of a given numerical index as simply the fraction f of ( hyper ) thermophile - mesophile pairs from a pairs set where that index is systematically larger or smaller for the ( hyper ) thermophilic protein , by any amount . for example , 86 . 1 % of the time for structure pairs in the pairs hyperthermophile set , the ratio ( e + k ) / ( q + h ) is greater for the hyperthermophilic than for the mesophilic protein , and so the discriminatory power is 0 . 861 .
the crystal structure of acetobacter aceti pure was determined to a resolution of 1 . 55 å and it is compared to the known structures of class i pures from a mesophile , escherichia coli , and a thermophile , thermotoga maritima . analyses of general factors that increase protein stability are examined as potential explanations for the acid stability of a . aceti pure . increased inter - subunit hydrogen bonding and increased arginine containing salt bridges appear to account for the bulk of the increased acid stability . a chain of histidines linking two active sites is discussed in the context of proton transfers catalyzed by the enzyme .
listeria monocytogenesis has a mesophile displaying optimum growth at 37°c and neutral ph . however , l . monocytogenes possesses elaborate physiological adaptation mechanisms towards various environmental stresses . in foods such stress conditions include low temperature ( refrigeration ) , increased osmotic strength ( salting or addition of sugars ) and increased acidity ( fermentation ) . undoubtedly , its psychrotrophic nature , i . e . the ability of l . monocytogenes to adapt and proliferate at low temperatures ( up to - 0 . 5°c ) , causes the most concern for the food industry , because refrigeration is the most common method of food preservation in developed countries .
in this study , we produced a series of chimeras from aks of the mesophile bacillus subtilis ( akmeso ) ( 20 ) and the thermophile bacillus stearothermophilus ( akthermo ) ( 21 ) . akmeso and akthermo share a high sequence identity ( 74 % ; fig . 1 c ) , and their structures are very similar ( 18 ) . this similarity allowed specific regions of the aks to be exchanged , producing fully functional chimeric aks . we subsequently analyzed them for temperature dependence of stability and activity to determine the roles of different regions in stability and catalysis of the enzyme and to ultimately study the relationship between structure , function , and dynamics of ak .
in this paper , we have addressed the discrimination problem where given sequences or structures from a mesophilic protein and a thermophilic or hyperthermophilic counterpart , the objective is to determine which is which . this was done by assembling a large set of thermophilic protein chains from the pdb and their corresponding mesophilic analogs and another large non - redundant set of hyperthermophilic pdb protein chains along with their mesophilic analogs . they will be referred to as the pairs sets : pairs - thermophile and pairs - hyperthermophile . we have computed several structure and sequence based numerical indices , based on the quantities that other authors have reported are associated with thermostability , and tested their ability , individually , to successfully discriminate between the thermophile / mesophile pairs . one could apply more sophisticated classification or regression techniques to a combination of these quantities , but for now we have opted for a very simple test of each quantity in isolation in order to verify if it is indeed consistently associated with increased thermostability .
c . perfringens is a mesophile who has a fastest growth rate at the temperature of 37 c [ 2 ] . when the spores of c . perfringens are exposed to a hyperthermal condition with a temperature of 105c for five minutes , their sensitivity to polymyxin and neomycin is increased significantly [ 6 ] . polymyxin is an antibiotic that damages the structure , the permeability and the rigidity of the bacterial plasma membrane , making the cell membrane too fragile to maintain the osmotic equilibrium [ 6 ] . neomycin is a metabolic inhibitor that stops protein synthesis [ 6 ] . therefore , polymyxin and neomycin can be used together to kill c . perfringens cells after exposing them to super high temperature for a short amount of time . this discovery is beneficial to human and animals , because the combination of polymyxin and neomycin can be used to control c . perfringens , which presents a threat as a toxic causative agent of many food - borne diseases . the results also implied that refrigerated food should be heated properly before eating them , because it can reduce the risk of getting c . perfringens - related illnesses .
the catalytic activity of a psychrophilic enzyme , due to the more flexible structure , is much greater at low temperatures than the same enzyme from a mesophile . in fact , despite decreased reaction rates at low temperatures , the specific activity ( ) of a psychrophilic enzyme is typically 10 times greater than a mesophilic enzyme [ 66 , 73 ] . a typical observation that is made to explain the greater is the increase in binding site size in psychrophilic proteins [ 64 ] . in psychrophilic enzymes , the substrate binding area is enlarged by a number of mechanisms while the catalytic residues are unchanged [ 66 ] . some of the mechanisms by which this area is enlarged include deletion of loops near the binding site [ 75 ] , strategic glycine residues near the functional sites [ 66 ] , and pulling the protein backbone out to increase substrate accessibility [ 76 ] . as a result , substrates are not able to bind as well to a psychrophilic enzyme , and , therefore , the michaelis - menten constant ( ) of psychrophilic enzymes is high [ 66 , 77 ] . poor substrate affinity improves enzyme activity at low temperatures because it reduces the energy of activation for the enzyme [ 66 ] .
the strategy used in this study can be generally applied . if a thermophilic homolog of a target protein is available , one can use the divide and swap method to produce a series of chimeras in which the desired region ( s ) is exchanged . then , temperature dependence of any properties of the chimeras can be analyzed and compared with those of the target protein and its thermophilic homolog to determine important region ( s ) for the properties . one of the advantages of this strategy is that consequence of the substitutions can be double checked . one can swap specific region ( s ) resulting in two chimeras , a mesophile with thermophilic part ( s ) and a thermophile with mesophilic part ( s ) , and test effect of the substitution in two directions . this approach is not limited to a pair of mesophilic and thermophilic homologs but can be applied to any set of homologous proteins with any distinct properties such as different activities , binding kinetics , or optimal functional conditions ( ph , pressure , salinity , etc . ) . thus , with increasing phylogenic knowledge of proteins and decreasing cost for synthetic genes , the strategy used in this study can be more applicable to many other studies .
thermal stability of dna ligases— thermal unfolding of ph lig , ec lig , and ts lig was monitored by differential scanning calorimetry ( dsc ) . a non - detergent sulfobetaine was added prior to dsc experiments ( see “experimental procedures” ) , in order to limit aggregation ( 29 ) that distorts the calorimetric traces and impairs deconvolution processes . fig . 5 illustrates the range of stabilities encountered within the dna ligase family , and table iii provides the thermodynamic parameters associated with thermal unfolding recorded by microcalorimetry . as indicated by the large differences in transition temperature t max , the psychrophilic enzyme is by far the least stable when compared with its mesophilic and thermophillic homologues . in addition , the lowest calorimetric enthalpy , representing the total heat absorbed during unfolding , is recorded for ph lig , underlining its weak thermostability . deconvolution of the excess heat capacity ( c p ) functions revealed one , two , and three subsequent transitions for ph lig , ec lig , and ts lig , respectively ( fig . 5 and table iii ) , pointing out the presence in the enzymes of an increased number of domains of distinct stability in the order psychrophile → mesophile → thermophile , also corresponding to a decrease of unfolding cooperativity .
listeria innocua is one of the six species belonging to the genus listeria . it is widely found in the environment ( such as soil ) and food sources . it can survive in extreme ph and temperature , and high salt concentration ( 5 ) . in terms of appearance , it is a rod - shaped gram - positive bacterium . it is a non - spore forming bacterium . it may live individually or organize into chains with other listeria innocua bacteria . it is a mesophile , operating at an optimal temperature range of 30 - 37 degrees celsius . listeria innocua very much resembles its other family members , the pathogenic listeria monocytogenes ( 5 ) . listeria innocua was isolated from meat by a technique called surface adhesion immunofluorescence ( 3 ) . samples of meat were inoculated with l . innocua and incubated at 30 degrees celsius for 14 - 18 hours in a broth . the cells were then isolated from the meat by surface adhesion onto a polycarbonate membrane attached to a microscope glass slide . then immunofluorescent microscopy was employed to visualize the bacteria ( 3 ) . listeria innocua is important because it is very similar to the food - borne pathogen l . monocytogenes but non - pathogenic in character . thus its genome was sequenced in order to compare it to the genome of l . monocytogenes to learn what makes the latter pathogenic .
the intervening domain of the thermostable thermus aquaticus dna polymerase ( taq polymerase ) , which has no catalytic activity , has been exchanged for the 3′–5′ exonuclease domain of the homologous mesophile escherichia coli dna polymerase i ( e . coli pol i ) and the homologous thermostable thermotoga neapolitana dna polymerase ( tne polymerase ) . three chimeric dna polymerases have been constructed using the three - dimensional ( 3d ) structure of the klenow fragment of the e . coli pol i and 3d models of the intervening and polymerase domains of the taq polymerase and the tne polymerase : chimera taqec1 ( exchange of residues 292–423 from taq polymerase for residues 327–519 of e . coli pol i ) , chimera taqtne1 ( exchange of residues 292–423 of taq polymerase for residues 295–485 of tne polymerase ) and chimera taqtne2 ( exchange of residues 292–448 of taq polymerase for residues 295–510 of tne polymerase ) . the chimera taqec1 showed characteristics from both parental polymerases at an intermediate temperature of 50°c : high polymerase activity , processivity , 3′–5′ exonuclease activity and proof - reading function . in comparison , the chimeras taqtne1 and taqtne2 showed no significant 3′–5′ exonuclease activity and no proof - reading function . the chimera taqtne1 showed an optimum temperature at 60°c , decreased polymerase activity compared with the taq polymerase and reduced processivity . the chimera taqtne2 showed high polymerase activity at 72°c , processivity and less reduced thermostability compared with the chimera taqtne1 .
a particular microorganism will exhibit a range of temperature over which it can grow , defined by three cardinal points in the same manner as ph ( figure 6 , cf . figure 4 ) . considering the total span of temperature where liquid water exists , the procaryotes may be subdivided into several subclasses on the basis of one or another of their cardinal points for growth . for example , organisms with an optimum temperature near 37 degrees ( the body temperature of warm - blooded animals ) are called mesophiles . organisms with an optimum t between about 45 degrees and 70 degrees are thermophiles . some archaea with an optimum t of 80 degrees or higher and a maximum t as high as 115 degrees , are now referred to as extreme thermophiles or hyperthermophiles . the cold - loving organisms are psychrophiles defined by their ability to grow at 0 degrees . a variant of a psychrophile ( which usually has an optimum t of 10 - 15 degrees ) is a psychrotroph , which grows at 0 degrees but displays an optimum t in the mesophile range , nearer room temperature . psychrotrophs are the scourge of food storage in refrigerators since they are invariably brought in from their mesophilic habitats and continue to grow in the refrigerated environment where they spoil the food . of course , they grow slower at 2 degrees than at 25 degrees . think how fast milk spoils on the counter top versus in the refrigerator .
whether particular amino acids are favored by selection at high temperatures over others has long been an open question in protein evolution . one way to approach this question is to compare homologous sites in proteins from one thermophile and a closely related mesophile ; asymmetrical substitution patterns have been taken as evidence for selection favoring certain amino acids over others . however , most pairs of prokaryotic species that differ in optimum temperature also differ in genome - wide gc content , and amino acid content is known to be associated with gc content . here , i compare homologous sites in nine thermophilic prokaryotes and their mesophilic relatives , all with complete published genome sequences . after adjusting for the effects of differing gc content with logistic regression , 139 of the 190 pairs of amino acids show significant substitutional asymmetry , evidence of widespread adaptive amino acid substitution . the patterns are fairly consistent across the nine pairs of species ( after taking the effects of differing gc content into account ) , suggesting that much of the asymmetry results from adaptation to temperature . some amino acids in some species pairs deviate from the overall pattern in ways indicating that adaptation to other environmental or physiological differences between the species may also play a role . the property that is best correlated with the patterns of substitutional asymmetry is transfer free energy , a measure of hydrophobicity , with more hydrophobic amino acids favored at higher temperatures . the correlation of asymmetry and hydrophobicity is fairly weak , suggesting that other properties may also be important .
here we show for the first time that biologically active solvent - free liquid proteins can be prepared using lipases from the mesophile rhizomucor miehei ( rml ) and thermophile thermomyces lanuginosus ( tll ) . the lipases comprise an active site based around a serine - histidine - aspartate triad ( ser144 - his257 - asp203 for rml , ser146 - his258 - asp201 for tll ) with substrate access regulated by conformational changes involving a helical ‘lid’ motif ( fig . 1a ) , and which together facilitate nucleophilic attack on the fatty acid ester substrate to produce the acylated enzyme and alcohol product ( fig . 1b ) . as a consequence , reaction in the solvent - free state requires substrate solubilization in the liquid enzyme , diffusion through the viscous melt , molecular access to the active site and conformational flexibility in the enzyme - polymer surfactant nanoconjugate . moreover , turnover of the lipases requires nucleophilic addition of a water molecule to liberate the carboxylic acid ( fig . 1b ) , which should be effectively curtailed in the solvent - free phase . in light of these considerations , we demonstrate that the new lipase biofluids directly solubilize and hydrolyse short - or long - chain fatty acid esters from both the solid ( p - nitrophenyl palmitate ; pnppal ) and liquid ( p - nitrophenyl butyrate ; pnpb ) phase with limited substrate turnover . significantly , the solvent - free liquid enzymes are extremely thermally stable , undergo re - folding from a half denaturation temperature of around 170 °c and , remarkably , exhibit increasing catalytic efficiency as the temperature is increased up to 150 °c .
we have studied the mean contribution to the 4 - body potential score q under a 7 - letter reduced alphabet to each structure in the mesophilic , thermophilic , and hyperthermophilic subsets of 521nonredundant . the reduced alphabet was used to simplify the analysis by bringing down the possible number of residue quadruplets that can reside at the vertices of a delaunay tetrahedron from 8855 for a 20 amino acid alphabet to 210 . the reduced alphabet is d , e , k , r , i = ( i , v ) , a = ( a , f , g , l , p ) , n = ( c , h , m , n , q , s , t , w , y . the four - body delaunay threading score q for a hyperthermophile with the average quadruplet composition is 36 . 3 , for a thermophile q is 28 . 2 , and for a mesophile q is 17 . 6 . for hyperthermophiles , the δq ( with respect to mesophiles ) attributable to quadruplets with at least two hydrophobic residues is + 11 . 07 , for quadruplets with at least two charged residues it is + 12 . 78 , and for quadruplets with at least two polar residues it is –2 . 53 . for thermophilic quadruplets the δq figures are : at least two hydrophobic residues + 5 . 99 , at least two charged residues + 4 . 55 , and at least two polar residues –0 . 34 . we see , therefore , that the 4 - body potential goes up for ( hyper ) thermophiles both due to associations between charged residues but also due to quadruplets of more highly hydrophobic residues . the increase in charged residues produces a larger change than the stronger hydrophobics with hyperthermophiles , but the situation is reversed in thermophiles .
while the common trait of a low conformational stability in cold - adapted enzymes has been demonstrated ( see ref . 11 for review ) , the stability / flexibility relationship is still controversial since some authors consider that the instability of psychrophilic enzymes is due to a random genetic drift ( 12 ) . moreover , if the decreased stability of cold - adapted enzymes is well documented , there is however , no direct experimental evidence of an increased flexibility . besides , controversial results were obtained when the flexibility of a few psychrophilic enzymes was investigated by measuring hydrogen - deuterieum exchange rates . in the case of 3 - isopropylmalate dehydrogenase ( 13 ) , while the psychrophilic and mesophilic enzymes were found more flexible than the thermophilic counterpart , the psychrophile was however more rigid than the mesophile . nevertheless , in this case , the technique suffered from the disadvantage of being a measure of the accessibility of deeply buried residues , and thus did not detect local flexibility , in particular that associated with the active site which is generally quite accessible . using a similar technique , fields ( 14 ) showed that while a psychrophilic and a mesophilic lactate dehydrogenases had similar flexibility at 2 °c , the global flexibility of the psychrophile was significantly larger at 23 °c . in addition to the lack of data about the flexibility of cold - adapted enzymes , information on the thermodynamics of inactivation and unfolding is also missing and the few available reports are controversial . indeed , siddiqui et al . ( 15 ) proposed that the thermolability of psychrophilic enzymes is due to enthalpic effects , while others ( 16 – 18 ) found this to be entropically driven . further studies are thus required to resolve whether an unfavorable entropic or enthalpic contribution determines the irreversible unfolding and inactivation of these enzymes .
although the patterns of asymmetry are consistent enough across species pairs to produce logistic regression models with significant intercepts , the amounts of asymmetry in each species pair are not exactly as predicted by the logistic regression ; many amino acids are favored more or less strongly in some species pairs than would be expected . the optimal temperatures of the species pairs differ by different amounts , from 15 to 55 °c , so it would have been startling if they all exhibited the exact same amount of asymmetry . the species pairs differ in how recently they diverged from a common ancestor , and the species pairs also vary in other aspects that may affect selection on amino acid use : aerobic versus anaerobic ; autotrophic versus heterotrophic ; marine , freshwater , and terrestrial ; and deep sea versus shallow water . species pairs in which the ancestral species was thermophilic and one lineage then adapted to lower temperatures may show different patterns of temperature adaptation than species pairs in which the ancestor was mesophilic and one lineage adapted to higher temperatures ( berezovsky and shakhnovich 2005 ) . there is also increasing evidence that biosynthetic costs may affect amino acid use ( akashi and gojobori 2002 ; seligmann 2003 ; heizer et al . 2006 ; swire 2007 ) , and the costs of particular amino acids will depend on factors that may be unrelated to temperature , such as the biosynthetic pathways used ( for autotrophs ) and environmental availability and uptake costs ( for heterotrophs ) . including all the possibly relevant variables when there are only nine species pairs would result in a logistic model that was completely overdetermined , with many spurious correlations ; separating the substitutional asymmetry caused by temperature adaptation from the asymmetry resulting from other causes will require examining the genomes of a much larger number of mesophile–thermophile species pairs than currently available .
ultraviolet–visible spectroscopy in transmission mode was used to assay the lipase activity of the solvent - free [ c - rml ] [ s 1 ] and [ c - tll ] [ s 1 ] liquids by monitoring the rate of formation of pnp ( ε 410 = 18 . 3 mm −1 cm −1 ) from pnpb at 30 °c ( fig . 1g ) . the initial rates of pnp formation by the [ c - rml ] [ s 1 ] and [ c - tll ] [ s 1 ] biofluids were estimated at 0 . 04±0 . 01 and 0 . 02±0 . 007 μmol min −1 mg −1 ( table 2 ) , respectively , which suggested that the mesophile - derived [ c - rml ] [ s 1 ] biofluid was more effective at physiological temperatures . control inhibition experiments using the serine protease inhibitor phenylmethanesulfonyl fluoride ( pmsf ) gave a significant reduction in the lipase activity ( ≈6 - fold ) of the [ c - rml ] [ s 1 ] biofluid with pnpb ( supplementary fig . 9 ) , which signified that the activity was associated with the ser - his - asp triad at the active site . it is possible that that partitioning of pmsf into the hydrophobic domains of the polymer surfactant corona reduced the efficacy of the inhibitor , although limited hydrolysis of the pnpb from an increase in the nucleophilicity of surface residues in the solvent - free state could not be ruled out . the initial rates of the uninhibited lipase biofluids were significantly lower than those determined for the respective aqueous native , cationized or conjugated proteins at 37 °c ( table 2 and supplementary figs 10 and 11 ) . this reduction in rate was attributed to the large resistance to substrate and product mass transfer arising from the high viscosity of the biofluids .
protein structure and active site destabilization— the three - dimensional modeling of the three extremophilic dna ligases ph lig , ec lig , and ts lig extend previous observations made for the n - terminal domain of ph lig ( 19 ) and provide further evidence for the structural determinants implicated in the adaptation to low temperatures of ph lig . our results suggest that the active site of the cold - enzyme is destabilized by an excess of hydrophobic surfaces and contains a decreased number of charged residues compared with its thermophilic counterpart . these findings are in perfect agreement with the kinetic parameters determined for both enzymes ( 19 ) . indeed , k cat is believed to be the most important adaptive parameter for ph lig hence compensating for the effect of low temperatures on the catalytic rate , while for ts lig , the adaptive parameter is expected to be k m for nicked dna , which is prone to melting at high temperatures . in the latter , the increase of positively charged amino acids within the active site is likely to facilitate the interaction with the oppositely charged dna substrate , leading to an improved k m . determination of the composition of the accessible surface of the whole molecule also points out an increase of the charged surface in the order psychrophile → mesophile → thermophile . such increase could lead to an increase of the ion pairs at the surface of ts lig , that could take part to its increased stability . indeed , ion pairs in solvent - exposed regions of thermophilic enzymes are believed to represent a major key in the adaptation of these enzymes at high temperatures ( 36 , 37 ) . analysis of the n - terminal domain of ph lig also revealed a significant increase of the degree of exposure of hydrophobic residues to solvent , which is expected to destabilize the protein structure ( 19 ) . while the model of the entire psychrophilic enzyme confirmed this finding , it was experimentally demonstrated by ans - binding experiments . indeed , most native globular proteins do not bind ans since their hydrophobic core is well protected from the solvent by the rigid packing of side chains ( 34 ) . however , when native proteins exhibit hydrophobic sites exposed to the solvent , a strong affinity for the dye is observed ( 34 , 35 ) . in the case of ph lig , the strong enhancement of fluorescence intensity of ans clearly demonstrates the exposure to solvent of hydrophobic clusters . the latter are likely to take part to an entropy - driven destabilization of the cold - adapted enzyme .


pseudotelphusa confixa is a moth of the family gelechiidae .

it is found in south africa .

the wingspan is 11 – 12 mm .

the forewings are dark grey suffusedly irrorated with white , with some black scales and with elongate blackish spots on the costa near the base , before the middle , and at two-thirds .

there is a black streak from beneath the first of these along the fold to near the extremity .

the discal stigmata are black connected by a black dash , the second followed by a disconnected black dash running nearly to the apex .

there are cloudy black marginal dots around the posterior part of the costa and termen .

the hindwings are grey , thinly scaled towards the base .

pseudotelphusa confixa

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pinhey e . c . g . 1975 . moths of southern africa . descriptions and colour illustrations of 1183 species . - — : i–iv , 1–273 , pls . 1–63 .
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[ south africa , gauteng ] , transvaal , pretoria , ii—iii , leg . c . j . swierstra .
meyrick e . 1918a . descriptions of south african micro - lepidoptera . - annals of the transvaal museum 6 ( 2 ) : 7—59 .
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to cite this page : myers , p . , r . espinosa , c . s . parr , t . jones , g . s . hammond , and t . a . dewey . 2018 . the animal diversity web ( online ) . accessed at https : / / animaldiversity . org .
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janse a . j . t . the moths of south africa . vi . gelechiadae — 1958
nomenclator zoologicus . a list of the names of genera and subgenera in zoology from the tenth edition of linnaeus , 1758 to the end of 2004 . digitised by ubio from vols . 1 - 9 of neave ( ed . ) , 1939 - 1996 plus supplementary digital - only volume . urltoken ( as at 2006 ) .
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