bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationship between Intracellular Phosphate, Proton Motive Force, and Rate of Nongrowth Energy Dissipation (Energy Spilling) in
Streptococcus bovis
JB1
Authors: Bond Daniel R. , Russell James B. 
Published: December 2019

ABSTRACT

When the rate of glucose addition to nongrowing
Streptococcus bovis
cell suspensions was increased, the fermentation was homolactic, fructose-1,6-diphosphate (FDP) increased, intracellular inorganic phosphate (P
i
) declined, and the energy-spilling rate increased. ATP and ADP were not significantly affected by glucose consumption rate, but the decrease in P
i
was sufficient to cause an increase in the free energy of ATP hydrolysis (ΔG′p). The increase in ΔG′p was correlated with an increase in proton motive force (Δp).
S. bovis
continuous cultures (dilution rate of 0.65 h
−1
) that were provided with ammonia as the sole nitrogen source also had high rates of lactate production and energy spilling. When Trypticase was added as a source of amino acids, lactate production decreased; a greater fraction of the glucose was converted to acetate, formate, and ethanol; and the energy-spilling rate decreased. Trypticase also caused a decrease in FDP, an increase in P
i
, and a decrease in Δp. The change in Δp could be explained by P
i
-dependent changes in the ΔG′p. When P
i
declined, ΔG′p and Δp increased. The ratio of ΔG′p to Δp (millivolt per millivolt) was always high (>4) at low rates of energy spilling but declined when the energy-spilling rate increased. Based on these results, it appears that Δp and the energy-spilling rate are responsive to fluctuations in the intracellular P
i
concentration.
Thermal Tolerance ofMycobacterium paratuberculosis
Authors: Sung Nackmoon , Collins Michael T. 
Published: December 2019

ABSTRACTDvalues (decimal reduction time; the time required to kill 1 log concentration of bacteria) were determined for both human and bovine strains (Dominic, Ben, BO45, and ATCC 19698) ofMycobacterium paratuberculosisin 50 mM lactate solution (pH 6.8) and in milk at four temperatures (62, 65, 68, and 71°C). ViableM. paratuberculosisorganisms were quantified by a radiometric culture method (BACTEC). Thermal death curves for theM. paratuberculosisstrains tested were generally linear, withR2of ≥0.90, but a few curves (R2, 0.80 to 0.90) were better described by a quadratic equation. The human strains (Dominic and Ben) had similarDvalues in milk and in lactate solution. However,Dvalues for the bovine strains (BO45 and ATCC 19698) were significantly different depending on the menstruum.Dvalues for low-passage clinical strains (Dominic, Ben, and BO45) were lower than those of the high-passage laboratory strain (ATCC 19698). TheDvalue based on pooled data for clinical strains ofM. paratuberculosisin milk at 71°C (D71°C) was 11.67 s. PooledD62°C,D65°C, andD68°Cof clinicalM. paratuberculosisstrains in milk were 228.8, 47.8, and 21.8 s, respectively. TheZvalue (the temperature required for the decimal reduction time to traverse 1 log cycle) of clinical strains in milk was 7.11°C. TheDvalues of clumped and singleM. paratuberculosiscells were not significantly different. TheDvalues of allM. paratuberculosisstrains tested were considerably higher than those published forListeria,Salmonella, andCoxiellaspp. and estimated forMycobacterium bovis, indicating thatM. paratuberculosisis more thermally tolerant. This study supports the premise thatM. paratuberculosismay survive high-temperature, short-time pasteurization when the initial organism concentration is greater than 101cells/ml.
A Novel Sensitive Bioassay for Detection of
Bacillus cereus
Emetic Toxin and Related Depsipeptide Ionophores
Authors: Andersson M. A. , Mikkola R. , Helin J. , Andersson M. C. , Salkinoja-Salonen M. 
Published: December 2019

ABSTRACT

Of the toxins produced by
Bacillus cereus
, the emetic toxin is likely the most dangerous but, due to the lack of a suitable assay, the least well known. In this paper, a new, sensitive, inexpensive, and rapid bioassay for detection of the emetic toxin of
B. cereus
is described. The assay is based on the loss of motility of boar spermatozoa upon 24 h of exposure to extracts of emetic
B. cereus
strains or contaminated food. The paralyzed spermatozoa exhibited swollen mitochondria, but no depletion of cellular ATP or damage to plasma membrane integrity was observed. Analysis of the purified toxin by electrospray tandem mass spectrometry showed that it was a dodecadepsipeptide with a mass fragmentation pattern similar to that described for cereulide. The 50% effective concentration of the purified toxin to boar spermatozoa was 0.5 ng of purified toxin ml of extended boar semen
−1
. This amount corresponds to 10
4
to 10
5
CFU of
B. cereus
cells. No toxicity was detected for 27 other
B. cereus
strains up to 10
8
CFU ml
−1
. The detection limit for food was 3 g of rice containing 10
6
to 10
7
CFU of emetic
B. cereus
per gram. Effects similar to those provoked by emetic
B. cereus
toxin were also induced in boar spermatozoa by valinomycin and gramicidin at 2 and 3 ng ml of extended boar semen
−1
, respectively. The symptoms provoked by the toxin in spermatozoa indicated that
B. cereus
emetic toxin was acting as a membrane channel-forming ionophore, damaging mitochondria and blocking the oxidative phosphorylation required for the motility of boar spermatozoa.
Effects of Soil on Ammonia, Ethylene, Chloroethane, and 1,1,1-Trichloroethane Oxidation by
Nitrosomonas europaea
Authors: Hommes Norman G. , Russell Sterling A. , Bottomley Peter J. , Arp Daniel J. 
Published: December 2019

ABSTRACT

Ammonia monooxygenase (AMO) from
Nitrosomonas europaea
catalyzes the oxidation of ammonia to hydroxylamine and has been shown to oxidize a variety of halogenated and nonhalogenated hydrocarbons. As part of a program focused upon extending these observations to natural systems, a study was conducted to examine the influence of soil upon the cooxidative abilities of
N. europaea
. Small quantities of Willamette silt loam (organic carbon content, 1.8%; cation-exchange capacity, 15 cmol/kg of soil) were suspended with
N. europaea
cells in a soil-slurry-type reaction mixture. The oxidations of ammonia and three different hydrocarbons (ethylene, chloroethane, and 1,1,1-trichloroethane) were compared to results for controls in which no soil was added. The soil significantly inhibited nitrite production from 10 mM ammonium by
N. europaea
. Inhibition resulted from a combination of ammonium adsorption onto soil colloids and the exchangeable acidity of the soil lowering the pH of the reaction mixture. These phenomena resulted in a substantial drop in the concentration of NH
4
+
in solution (10 to 4.5 mM) and, depending upon the pH, in a reduction in the amount of available NH
3
to concentrations (8 to 80 μM) similar to the

K
s

value of AMO for NH
3
(∼29 μM). At a fixed initial pH (7.8), the presence of soil also modified the rates of oxidation of ethylene and chloroethane and changed the concentrations at which their maximal rates of oxidation occurred. The modifying effects of soil on nitrite production and on the cooxidation of ethylene and chloroethane could be circumvented by raising the ammonium concentration in the reaction mixture from 10 to 50 mM. Soil had virtually no effect on the oxidation of 1,1,1-trichloroethane.
Molecular Cloning and Transcriptional Regulation of theAspergillus nidulans xlnDGene Encoding a β-Xylosidase
Authors: Pérez-González José A. , van Peij Noël N. M. E. , Bezoen Alja , Maccabe Andrew P. , Ramón Daniel , de Graaff Leo H. 
Published: December 2019

ABSTRACTThexlnDgene encoding the 85-kDa β-xylosidase was cloned fromAspergillus nidulans. The deduced primary structure of the protein exhibits considerable similarity to the primary structures of theAspergillus nigerandTrichoderma reeseiβ-xylosidases and some similarity to the primary structures of the class 3 β-glucosidases.xlnDis regulated at the transcriptional level; it is induced by xylan andd-xylose and is repressed byd-glucose. Glucose repression is mediated by the product of thecreAgene. Although several binding sites for the pH regulatory protein PacC were found in the upstream regulatory region, it was not clear from a Northern analysis whether PacC is involved in transcriptional regulation ofxlnD.
Analysis of the β-1,3-Glucanolytic System of the Biocontrol AgentTrichoderma harzianum
Authors: Vázquez-Garcidueñas Soledad , Leal-Morales Carlos A. , Herrera-Estrella Alfredo 
Published: December 2019

ABSTRACTThe biocontrol agentTrichoderma harzianumIMI206040 secretes β-1,3-glucanases in the presence of different glucose polymers and fungal cell walls. The level of β-1,3-glucanase activity secreted was found to be proportional to the amount of glucan present in the inducer. The fungus produces at least seven extracellular β-1,3-glucanases upon induction with laminarin, a soluble β-1,3-glucan. The molecular weights of five of these enzymes fall in the range from 60,000 to 80,000, and their pIs are 5.0 to 6.8. In addition, a 35-kDa protein with a pI of 5.5 and a 39-kDa protein are also secreted. Glucose appears to inhibit the formation of all of the inducible β-1,3-glucanases detected. A 77-kDa glucanase was partially purified from the laminarin culture filtrate. This enzyme is glycosylated and belongs to the exo-β-1,3-glucanase group. The properties of this complex group of enzymes suggest that the enzymes might play different roles in host cell wall lysis during mycoparasitism.
Use of
13
C Nuclear Magnetic Resonance To Assess Fossil Fuel Biodegradation: Fate of [1-
13
C]Acenaphthene in Creosote Polycyclic Aromatic Compound Mixtures Degraded by Bacteria
Authors: Selifonov Sergey A. , Chapman Peter J. , Akkerman Simon B. , Gurst Jerome E. , Bortiatynski Jacqueline M. , Nanny Mark A. , Hatcher Patrick G. 
Published: December 2019

ABSTRACT

[1-
13
C]acenaphthene, a tracer compound with a nuclear magnetic resonance (NMR)-active nucleus at the C-1 position, has been employed in conjunction with a standard broad-band-decoupled
13
C-NMR spectroscopy technique to study the biodegradation of acenaphthene by various bacterial cultures degrading aromatic hydrocarbons of creosote. Site-specific labeling at the benzylic position of acenaphthene allows
13
C-NMR detection of chemical changes due to initial oxidations catalyzed by bacterial enzymes of aromatic hydrocarbon catabolism. Biodegradation of [1-
13
C]acenaphthene in the presence of naphthalene or creosote polycyclic aromatic compounds (PACs) was examined with an undefined mixed bacterial culture (established by enrichment on creosote PACs) and with isolates of individual naphthalene- and phenanthrene-degrading strains from this culture. From
13
C-NMR spectra of extractable materials obtained in time course biodegradation experiments under optimized conditions, a number of signals were assigned to accumulated products such as 1-acenaphthenol, 1-acenaphthenone, acenaphthene-1,2-diol and naphthalene 1,8-dicarboxylic acid, formed by benzylic oxidation of acenaphthene and subsequent reactions. Limited degradation of acenaphthene could be attributed to its oxidation by naphthalene 1,2-dioxygenase or related dioxygenases, indicative of certain limitations of the undefined mixed culture with respect to acenaphthene catabolism. Coinoculation of the mixed culture with cells of acenaphthene-grown strain
Pseudomonas
sp. strain A2279 mitigated the accumulation of partial transformation products and resulted in more complete degradation of acenaphthene. This study demonstrates the value of the stable isotope labeling approach and its ability to reveal incomplete mineralization even when as little as 2 to 3% of the substrate is incompletely oxidized, yielding products of partial transformation. The approach outlined may prove useful in assessing bioremediation performance.
Ammonium Limitation Results in the Loss of Ammonia-Oxidizing Activity inNitrosomonas europaea
Authors: Stein Lisa Y. , Arp Daniel J. 
Published: December 2019

ABSTRACTThe effects of limiting concentrations of ammonium on the metabolic activity ofNitrosomonas europaea, an obligate ammonia-oxidizing soil bacterium, were investigated. Cells were harvested during late logarithmic growth and were incubated for 24 h in growth medium containing 0, 15, or 50 mM ammonium. The changes in nitrite production and the rates of ammonia- and hydroxylamine-dependent oxygen consumption were monitored. In incubations without ammonium, there was little change in the ammonia oxidation activity after 24 h. With 15 mM ammonium, an amount that was completely consumed, there was an 85% loss of the ammonia oxidation activity after 24 h. In contrast, there was only a 35% loss of the ammonia oxidation activity after 24 h in the presence of 50 mM ammonium, an amount that was not consumed to completion. There was little effect on the hydroxylamine oxidation activity in any of the incubations. The loss of ammonia oxidation activity was not due to differences in steady-state levels of ammonia monooxygenase (AMO) mRNA (amoA) or to degradation of the active site-containing subunit of AMO protein. The incubations were also conducted at a range of pH values to determine whether the loss of ammonia oxidation activity was correlated to the residual ammonium concentration. The loss of ammonia oxidation activity after 24 h was less at lower pH values (where the unoxidized ammonium concentration was higher). When added in conjunction with limiting ammonium, short-chain alkanes, which are alternative substrates for AMO, prevented the loss of ammonia oxidation activity at levels corresponding to their binding affinity for AMO. These results suggest that substrates of AMO can preserve the ammonia-oxidizing activity ofN. europaeain batch incubations by protecting either AMO itself or other molecules associated with ammonia oxidation.
Effects of Cellular Metabolism and Viability on Metal Ion Accumulation by Cultured Biomass from a Bloom of the Cyanobacterium
Microcystis aeruginosa
Authors: Parker D. L. , Rai L. C. , Mallick N. , Rai P. K. , Kumar H. D. 
Published: December 2019

ABSTRACT

The sorption of nickel, cadmium, and copper by cultured biomass from a naturally occurring bloom of
Microcystis aeruginosa
was demonstrated in two systems: cells suspended in culture medium and cells immobilized in alginate. Incubation in the absence of light, in the presence of metabolic inhibitors, and at 4°C did not substantially decrease the copper accumulation by cells in culture medium. Heat-killed, formaldehyde-treated, and air-dried biomass samples sorbed nearly as much (or in some cases slightly more) copper as did viable samples.
Changes in Permeability of Brush Border Membrane Vesicles from
Spodoptera littoralis
Midgut Induced by Insecticidal Crystal Proteins from
Bacillus thuringiensis
Authors: Escriche B. , De Decker N. , Van Rie J. , Jansens S. , Van Kerkhove E. 
Published: December 2019

ABSTRACT

Bacillus thuringiensis
insecticidal crystal proteins (ICPs) are thought to induce pore formation in midgut cell membranes of susceptible insects. Cry1Ca, which is significantly active in
Spodoptera littoralis
, made brush border membrane vesicles permeable to KCl (osmotic swelling was monitored by the light scattering technique); the marginally active ICPs Cry1Aa, Cry1Ab, and Cry1Ac did not.
Chemotaxis of Pathogenic
Vibrio
Strains towards Mucus Surfaces of Gilt-Head Sea Bream (
Sparus aurata
L.)
Authors: Bordas M. Angeles , Balebona M. Carmen , Rodriguez-Maroto Jose M. , Borrego Juan J. , Moriñigo Miguel A. 
Published: December 2019

ABSTRACT

Vibrio anguillarum
and
Vibrio alginolyticus
exhibited significant adhesion to and chemotactic abilities towards mucus collected from the skin, gills, and intestine of gilt-head sea bream. Quadratic polynomial models for chemotaxis designed to estimate the influence of temperature demonstrated a differential bacterial chemotaxis depending of the source of the mucus, with the chemotaxis towards intestinal mucus being the least influenced.
High-Fidelity Translation of Recombinant Human Hemoglobin in
Escherichia coli
Authors: Weickert Michael J. , Apostol Izydor 
Published: December 2019

ABSTRACT

Coexpression of di-α-globin and β-globin in
Escherichia coli
in the presence of exogenous heme yielded high levels of soluble, functional recombinant human hemoglobin (rHb1.1). High-level expression of rHb1.1 provides a good model for measuring mistranslation in heterologous proteins. rHb1.1 does not contain isoleucine; therefore, any isoleucine present could be attributed to mistranslation, most likely mistranslation of one or more of the 200 codons that differ from an isoleucine codon by 1 bp. Sensitive amino acid analysis of highly purified rHb1.1 typically revealed ≤0.2 mol of isoleucine per mol of hemoglobin. This corresponds to a translation error rate of ≤0.001, which is not different from typical translation error rates found for
E. coli
proteins. Two different expression systems that resulted in accumulation of globin proteins to levels equivalent to ∼20% of the level of
E. coli
soluble proteins also resulted in equivalent translational fidelity.
Phylogeny and Identification In Situ of
Nevskia ramosa
Authors: Glöckner Frank Oliver , Babenzien Hans-Dietrich , Amann Rudolf 
Published: December 2019

ABSTRACT

An enrichment of the neuston bacterium
Nevskia ramosa
was investigated by the cultivation-independent rRNA approach.
N. ramosa
was first described by Famintzin in 1892 as a rod-shaped, slightly bent bacterium forming typical flat rosettes on the surface of shallow freshwater habitats by unilateral slime formation. PCR in combination with cloning and sequencing was used for retrieving 21 partial and 5 nearly full-length 16S rRNA sequences forming three tight clusters. In situ hybridization with rRNA-targeted oligonucleotide probes allowed us to assign the three sequence clusters to three distinct bacterial populations abundant in the enrichment. The two probes that unambiguously identified the
N. ramosa
morphotype were derived from a 16S rRNA sequence that had similarities of 87.9 to 88.9% to the rRNA sequences of the most closely related group in the database,
Xanthomonas
sp. and relatives.
N. ramosa
currently is the only representative of an independent, deep branch of the gamma subclass of the class
Proteobacteria
. The two other populations abundant in the enrichment were affiliated with the alpha subclass of the class
Proteobacteria
. They were most closely related to
Blastobacter
sp. (97.2% similarity) and
Mycoplana bullata
(97.6% similarity) and might represent new species in the respective genera.
Phanerochaete chrysosporium
Cellobiohydrolase and Cellobiose Dehydrogenase Transcripts in Wood
Authors: Vallim Marcelo A. , Janse Bernard J. H. , Gaskell Jill , Pizzirani-Kleiner Aline A. , Cullen Daniel 
Published: December 2019

ABSTRACT

The transcripts of structurally related cellobiohydrolase genes in
Phanerochaete chrysosporium
-colonized wood chips were quantified. The transcript patterns obtained were dramatically different from the transcript patterns obtained previously in defined media. Cellobiose dehydrogenase transcripts were also detected, which is consistent with the hypothesis that such transcripts play an important role in cellulose degradation.
Lysis of
Lactococcus lactis
subsp.
cremoris
SK110 and Its Nisin-Immune Transconjugant in Relation to Flavor Development in Cheese
Authors: Meijer Wilco , van de Bunt Bert , Twigt Marja , de Jonge Boudewijn , Smit Gerrit , Hugenholtz Jeroen 
Published: December 2019

ABSTRACT

To develop a nisin-producing cheese starter,
Lactococcus lactis
subsp.
cremoris
SK110 was conjugated with transposon Tn
5276
-NI, which codes for nisin immunity but not for nisin production. Cheese made with transconjugant SK110::Tn
5276
-NI as the starter was bitter. The muropeptide of the transconjugant contained a significantly greater amount of tetrapeptides than the muropeptide of strain SK110, which could have decreased the susceptibility of the cells to lysis and thereby the release of intracellular debittering enzymes.
The Contribution of Caseins to the Amino Acid Supply for
Lactococcus lactis
Depends on the Type of Cell Envelope Proteinase
Authors: Flambard Benedicte , Helinck Sandra , Richard Jean , Juillard Vincent 
Published: December 2019

ABSTRACT

The ability of caseins to fulfill the amino acid requirements of
Lactococcus lactis
for growth was studied as a function of the type of cell envelope proteinase (P
I
versus P
III
type). Two genetically engineered strains of
L. lactis
that differed only in the type of proteinase were grown in chemically defined media containing α
s1
-, β-, and κ-caseins (alone or in combination) as the sources of amino acids. Casein utilization resulted in limitation of the growth rate, and the extent of this limitation depended on the type of casein and proteinase. Adding different mixtures of essential amino acids to the growth medium made it possible to identify the nature of the limitation. This procedure also made it possible to identify the amino acid deficiency which was growth rate limiting for
L. lactis
in milk (S. Helinck, J. Richard, and V. Juillard, Appl. Environ. Microbiol. 63:2124–2130, 1997) as a function of the type of proteinase. Our results were compared with results from previous in vitro experiments in which casein degradation by purified proteinases was examined. The results were in agreement only in the case of the P
I
-type proteinase. Therefore, our results bring into question the validity of the in vitro approach to identification of casein-derived peptides released by a P
III
-type proteinase.
Establishment of New Genetic Traits in a Microbial Biofilm Community
Authors: Christensen Bjarke B. , Sternberg Claus , Andersen Jens Bo , Eberl Leo , Møller Søren , Givskov Michael , Molin Søren 
Published: December 2019

ABSTRACT

Conjugational transfer of the TOL plasmid (pWWO) was analyzed in a flow chamber biofilm community engaged in benzyl alcohol degradation. The community consisted of three species,
Pseudomonas putida
RI,
Acinetobacter
sp. strain C6, and an unidentified isolate, D8. Only
P. putida
RI could act as a recipient for the TOL plasmid. Cells carrying a chromosomally integrated
lacI
q
gene and a
lacp-gfp
-tagged version of the TOL plasmid were introduced as donor strains in the biofilm community after its formation. The occurrence of plasmid-carrying cells was analyzed by viable-count-based enumeration of donors and transconjugants. Upon transfer of the plasmids to the recipient cells, expression of green fluorescence was activated as a result of zygotic induction of the
gfp
gene. This allowed a direct in situ identification of cells receiving the
gfp
-tagged version of the TOL plasmid. Our data suggest that the frequency of horizontal plasmid transfer was low, and growth (vertical transfer) of the recipient strain was the major cause of plasmid establishment in the biofilm community. Employment of scanning confocal laser microscopy on fixed biofilms, combined with simultaneous identification of
P. putida
cells and transconjugants by 16S rRNA hybridization and expression of green fluorescence, showed that transconjugants were always associated with noninfected
P. putida
RI recipient microcolonies. Pure colonies of transconjugants were never observed, indicating that proliferation of transconjugant cells preferentially took place on preexisting
P. putida
RI microcolonies in the biofilm.