bluuebunny/crossref_metadata_2025_split huggingface dataset:
Life under Multiple Extreme Conditions: Diversity and Physiology of the Halophilic Alkalithermophiles
Authors: Mesbah Noha M. , Wiegel Juergen 
Published: April 2012

ABSTRACT
Around the world, there are numerous alkaline, hypersaline environments that are heated either geothermally or through intense solar radiation. It was once thought that such harsh environments were inhospitable and incapable of supporting a variety of life. However, numerous culture-dependent and -independent studies revealed the presence of an extensive diversity of aerobic and anaerobic bacteria and archaea that survive and grow under these multiple harsh conditions. This diversity includes the halophilic alkalithermophiles, a novel group of polyextremophiles that require for growth and proliferation the multiple extremes of high salinity, alkaline pH, and elevated temperature. Life under these conditions undoubtedly involves the development of unique physiological characteristics, phenotypic properties, and adaptive mechanisms that enable control of membrane permeability, control of intracellular osmotic balance, and stability of the cell wall, intracellular proteins, and other cellular constituents. This minireview highlights the ecology and growth characteristics of the extremely halophilic alkalithermophiles that have been isolated thus far. Biochemical, metabolic, and physiological properties of the extremely halophilic alkalithermophiles are described, and their roles in resistance to the combined stressors of high salinity, alkaline pH, and high temperature are discussed. The isolation of halophilic alkalithermophiles broadens the physicochemical boundaries for life and extends the boundaries for the combinations of the maximum salinity, pH, and temperature that can support microbial growth.
Resistance to Broad-Spectrum Antibiotics in Aquatic Systems: Anthropogenic Activities Modulate the Dissemination of
bla
CTX-M
-Like Genes
Authors: Tacão Marta , Correia António , Henriques Isabel 
Published: April 2012

ABSTRACT

We compared the resistomes within polluted and unpolluted rivers, focusing on extended-spectrum beta-lactamase (ESBL) genes, in particular
bla
CTX-M
. Twelve rivers from a Portuguese hydrographic basin were sampled. Physicochemical and microbiological parameters of water quality were determined, and the results showed that 9 rivers were classified as unpolluted (UP) and that 3 were classified as polluted (P). Of the 225 cefotaxime-resistant strains isolated, 39 were identified as ESBL-producing strains, with 18 carrying a
bla
CTX-M
gene (15 from P and 3 from UP rivers). Analysis of CTX-M nucleotide sequences showed that 17 isolates produced CTX-M from group 1 (CTX-M-1, -3, -15, and -32) and 1 CTX-M that belonged to group 9 (CTX-M-14). A genetic environment study revealed the presence of different genetic elements previously described for clinical strains. IS
Ecp1
was found in the upstream regions of all isolates examined. Culture-independent
bla
CTX-M
-like libraries were comprised of 16 CTX-M gene variants, with 14 types in the P library and 4 types in UP library, varying from 68% to 99% similarity between them. Besides the much lower level of diversity among CTX-M-like genes from UP sites, the majority were similar to chromosomal ESBLs such as
bla
RAHN-1
. The results demonstrate that the occurrence and diversity of
bla
CTX-M
genes are clearly different between polluted and unpolluted lotic ecosystems; these findings favor the hypothesis that natural environments are reservoirs of resistant bacteria and resistance genes, where anthropogenic-driven selective pressures may be contributing to the persistence and dissemination of genes usually relevant in clinical environments.
Biosynthesis of Fusarubins Accounts for Pigmentation of Fusarium fujikuroi Perithecia
Authors: Studt Lena , Wiemann Philipp , Kleigrewe Karin , Humpf Hans-Ulrich , Tudzynski Bettina 
Published: April 2012

ABSTRACTFusarium fujikuroiproduces a variety of secondary metabolites, of which polyketides form the most diverse group. Among these are the highly pigmented naphthoquinones, which have been shown to possess different functional properties for the fungus. A group of naphthoquinones, polyketides related to fusarubin, were identified inFusariumspp. more than 60 years ago, but neither the genes responsible for their formation nor their biological function has been discovered to date. In addition, although it is known that the sexual fruiting bodies in which the progeny of the fungus develops are darkly colored by a polyketide synthase (PKS)-derived pigment, the structure of this pigment has never been elucidated. Here we present data that link the fusarubin-type polyketides to a defined gene cluster, which we designatefsr, and demonstrate that the fusarubins are the pigments responsible for the coloration of the perithecia. We studied their regulation and the function of the single genes within the cluster by a combination of gene replacements and overexpression of the PKS-encoding gene, and we present a model for the biosynthetic pathway of the fusarubins based on these data.
Expression of Chlorite Dismutase and Chlorate Reductase in the Presence of Oxygen and/or Chlorate as the Terminal Electron Acceptor in Ideonella dechloratans
Authors: Hellberg Lindqvist Miriam , Johansson Nicklas , Nilsson Thomas , Rova Maria 
Published: April 2012

ABSTRACT

The ability of microorganisms to perform dissimilatory (per)chlorate reduction is, for most species, known to be oxygen sensitive. Consequently, bioremediation processes for the removal of oxochlorates will be disturbed if oxygen is present. We measured the expression of chlorite dismutase and chlorate reductase in the presence of different terminal electron acceptors in the chlorate reducer
Ideonella dechloratans
. Enzyme activity assays and mRNA analyses by real-time quantitative reverse transcription (qRT)-PCR were performed on cell extracts from cells grown aerobically with and without chlorate and on cells grown anaerobically in the presence of chlorate. Our results showed that both chlorite dismutase and chlorate reductase are expressed during aerobic growth. However, transfer to anaerobic conditions with chlorate resulted in significantly enhanced enzyme activities and mRNA levels for both enzymes. Absence of oxygen was necessary for the induction to occur, since chlorate addition under aerobic conditions produced neither increased enzyme activities nor higher relative levels of mRNA. For chlorite dismutase, the observed increase in activity was on the same order of magnitude as the increase in the relative mRNA level, indicating gene regulation at the transcriptional level. However, chlorate reductase showed about 200 times higher enzyme activity in anaerobically induced cells, whereas the increase in mRNA was only about 10-fold, suggesting additional mechanisms influence the enzyme activity.
No Evidence for Transmission of Antibiotic-Resistant Escherichia coli Strains from Humans to Wild Western Lowland Gorillas in Lopé National Park, Gabon
Authors: Benavides Julio Andre , Godreuil Sylvain , Bodenham Rebecca , Ratiarison Sandra , Devos Céline , Petretto Marie-Odile , Raymond Michel , Escobar-Páramo Patricia 
Published: April 2012

ABSTRACT

The intensification of human activities within the habitats of wild animals is increasing the risk of interspecies disease transmission. This risk is particularly important for great apes, given their close phylogenetic relationship with humans. Areas of high human density or intense research and ecotourism activities expose apes to a high risk of disease spillover from humans. Is this risk lower in areas of low human density? We determined the prevalence of
Escherichia coli
antibiotic-resistant isolates in a population of the critically endangered western lowland gorilla (
Gorilla gorilla gorilla
) and other wild mammals in Lopé National Park (LNP), Gabon, and we tested whether the observed pattern could be explained by bacterial transmission from humans and domestic animals into wildlife populations. Our results show a high prevalence of antibiotic-resistant bacterial isolates in humans and low levels in gorillas and other wildlife. The significant differences in the genetic background of the resistant bacteria isolated from humans and gorillas suggest that transmission is low or does not occur between these two species. These findings indicate that the presence of antibiotic-resistant strains in wildlife do not imply direct bacteria transmission from humans. Thus, in areas of low human density, human-wildlife
E. coli
transmission seems to be low. The presence of antibiotic-resistant isolates in gorillas may be better explained by other mechanisms for resistance acquisition, such as horizontal gene exchange among bacteria or naturally acquired resistance.
Fungal Endophytic Communities in Grapevines (Vitis vinifera L.) Respond to Crop Management
Authors: Pancher Michael , Ceol Marco , Corneo Paola Elisa , Longa Claudia Maria Oliveira , Yousaf Sohail , Pertot Ilaria , Campisano Andrea 
Published: April 2012

ABSTRACTWe studied the distribution of fungal endophytes of grapevine (Vitis viniferaL.) plants in a subalpine area of northern Italy, where viticulture is of high economic relevance. We adopted both cultivation-based and cultivation-independent approaches to address how various anthropic and nonanthropic factors shape microbial communities. Grapevine stems were harvested from several locations considering organic and integrated pest management (IPM) and from the cultivars Merlot and Chardonnay. Cultivable fungi were isolated and identified by internal-transcribed-spacer sequence analysis, using a novel colony-PCR method, to amplify DNA from fungal specimens. The composition of fungal communities was assessed using a cultivation-independent approach, automated ribosomal intergenic spacer analysis (ARISA). Multivariate statistical analysis of both culture-dependent and culture-independent data sets was convergent and indicated that fungal endophytic communities in grapevines from organically managed farms were different from those from farms utilizing IPM. Fungal communities in plants of cv. Merlot and cv. Chardonnay overlapped when analyzed using culture-dependent approaches but could be partially resolved using ARISA fingerprinting.
Regulation of Polyphosphate Kinase Production by Antisense RNA in Pseudomonas fluorescens Pf0-1
Authors: Silby Mark W. , Nicoll Julie S. , Levy Stuart B. 
Published: April 2012

ABSTRACTPseudomonasspp. adapt rapidly to environmental fluctuations. Loss or overproduction of polyphosphate reduces the fitness ofPseudomonas fluorescensPf0-1, indicating the importance of the fine-tuning of polyphosphate production. An antisense RNA was investigated and shown to regulate the polyphosphate kinase gene (ppk) by a posttranscriptional mechanism reducingppktranscript abundance.
Low-Temperature Decontamination with Hydrogen Peroxide or Chlorine Dioxide for Space Applications
Authors: Pottage T. , Macken S. , Giri K. , Walker J. T. , Bennett A. M. 
Published: April 2012

ABSTRACT

The currently used microbial decontamination method for spacecraft and components uses dry-heat microbial reduction at temperatures of >110°C for extended periods to prevent the contamination of extraplanetary destinations. This process is effective and reproducible, but it is also long and costly and precludes the use of heat-labile materials. The need for an alternative to dry-heat microbial reduction has been identified by space agencies. Investigations assessing the biological efficacy of two gaseous decontamination technologies, vapor hydrogen peroxide (Steris) and chlorine dioxide (ClorDiSys), were undertaken in a 20-m
3
exposure chamber. Five spore-forming
Bacillus
spp. were exposed on stainless steel coupons to vaporized hydrogen peroxide and chlorine dioxide gas. Exposure for 20 min to vapor hydrogen peroxide resulted in 6- and 5-log reductions in the recovery of
Bacillus atrophaeus
and
Geobacillus stearothermophilus
, respectively. However, in comparison, chlorine dioxide required an exposure period of 60 min to reduce both
B. atrophaeus
and
G. stearothermophilus
by 5 logs. Of the three other
Bacillus
spp. tested,
Bacillus thuringiensis
proved the most resistant to hydrogen peroxide and chlorine dioxide with D values of 175.4 s and 6.6 h, respectively. Both low-temperature decontamination technologies proved effective at reducing the
Bacillus
spp. tested within the exposure ranges by over 5 logs, with the exception of
B. thuringiensis
, which was more resistant to both technologies. These results indicate that a review of the indicator organism choice and loading could provide a more appropriate and realistic challenge for the sterilization procedures used in the space industry.
Purification and Characterization of the Acetone Carboxylase of Cupriavidus metallidurans Strain CH34
Authors: Rosier Caroline , Leys Natalie , Henoumont Céline , Mergeay Max , Wattiez Ruddy 
Published: April 2012

ABSTRACT

Acetone carboxylase (Acx) is a key enzyme involved in the biodegradation of acetone by bacteria. Except for the
Helicobacteraceae
family, genome analyses revealed that bacteria that possess an Acx, such as
Cupriavidus metallidurans
strain CH34, are associated with soil. The Acx of CH34 forms the heterohexameric complex α
2
β
2
γ
2
and can carboxylate only acetone and 2-butanone in an ATP-dependent reaction to acetoacetate and 3-keto-2-methylbutyrate, respectively.
Biogenesis of Outer Membrane Vesicles in Serratia marcescens Is Thermoregulated and Can Be Induced by Activation of the Rcs Phosphorelay System
Authors: McMahon Kenneth J. , Castelli Maria E. , Vescovi Eleonora García , Feldman Mario F. 
Published: April 2012

ABSTRACT

Outer membrane vesicles (OMVs) have been identified in a wide range of bacteria, yet little is known of their biogenesis. It has been proposed that OMVs can act as long-range toxin delivery vectors and as a novel stress response. We have found that the formation of OMVs in the Gram-negative opportunistic pathogen
Serratia marcescens
is thermoregulated, with a significant amount of OMVs produced at 22 or 30°C and negligible quantities formed at 37°C under laboratory conditions. Inactivation of the synthesis of the enterobacterial common antigen (ECA) resulted in a hypervesiculation phenotype, supporting the hypothesis that OMVs are produced in response to stress. We demonstrate that the phenotype can be reversed to wild-type (WT) levels upon the loss of the Rcs phosphorelay response regulator RcsB, but not RcsA, suggesting a role for the Rcs phosphorelay in the production of OMVs. MS fingerprinting of the OMVs provided evidence of cargo selection within wild-type cells, suggesting a possible role for
Serratia
OMVs in toxin delivery. In addition, OMV-associated cargo proved toxic upon injection into the haemocoel of
Galleria mellonella
larvae. These experiments demonstrate that OMVs are the result of a regulated process in
Serratia
and suggest that OMVs could play a role in virulence.
Germination Protein Levels and Rates of Germination of Spores of Bacillus subtilis with Overexpressed or Deleted Genes Encoding Germination Proteins
Authors: Stewart Kerry-Ann V. , Yi Xuan , Ghosh Sonali , Setlow Peter 
Published: April 2012

ABSTRACT

Deletion of
Bacillus subtilis
spores' GerA germinant receptor (GR) had no effect on spore germination via the GerB plus GerK GRs, and loss of GerB plus GerK did not affect germination via GerA. Loss of one or two GRs also did not affect levels of GRs that were not deleted. Overexpression of GRs 5- to 18-fold increased rates of germination via the overexpressed GR and slowed germination by other GRs up to 15-fold. However, overexpression of one or two GRs had no effect on levels of GRs that were not overexpressed. These results suggest that either interaction between different GRs reduces the activity of GRs in triggering spore germination or all GRs compete for interaction with a limiting amount of a downstream signaling molecule in the germination pathway. Overexpression or deletion of GRs also had no effect on spores' levels of the GerD protein needed for normal GR-dependent germination or of the SpoVAD protein likely involved in dipicolinic acid release early in germination. Loss of GerD also had no effect on levels of GRs or SpoVAD. Spores of a strain lacking the only
B. subtilis
prelipoprotein diacylglycerol transferase, GerF, also had no detectable GerD or the GerA's C subunit, both of which are most likely lipoproteins; GerA's A subunit was also absent. However, levels of GerB's C subunit, also almost certainly a lipoprotein, and GerK's A subunit were normal in
gerF
spores. These results with g
erF
spores were consistent with effects of loss of GerF on spore germination by different GRs.
The Phosphodiesterase DipA (PA5017) Is Essential for Pseudomonas aeruginosa Biofilm Dispersion
Authors: Roy Ankita Basu , Petrova Olga E. , Sauer Karin 
Published: April 2012

ABSTRACTAlthough little is known regarding the mechanism of biofilm dispersion, it is becoming clear that this process coincides with alteration of cyclic di-GMP (c-di-GMP) levels. Here, we demonstrate that dispersion byPseudomonas aeruginosain response to sudden changes in nutrient concentrations resulted in increased phosphodiesterase activity and reduction of c-di-GMP levels compared to biofilm and planktonic cells. By screening mutants inactivated in genes encoding EAL domains for nutrient-induced dispersion, we identified in addition to the previously reported ΔrbdAmutant a second mutant, the ΔdipAstrain (PA5017 [dispersion-inducedphosphodiesterase A]), to be dispersion deficient in response to glutamate, nitric oxide, ammonium chloride, and mercury chloride. Using biochemical andin vivostudies, we show that DipA associates with the membrane and exhibits phosphodiesterase activity but no detectable diguanylate cyclase activity. Consistent with these data, a ΔdipAmutant exhibited reduced swarming motility, increased initial attachment, and polysaccharide production but only somewhat increased biofilm formation and c-di-GMP levels. DipA harbors an N-terminal GAF (cGMP-specific phosphodiesterases,adenylyl cyclases, andFhlA) domain and two EAL motifs within or near the C-terminal EAL domain. Mutational analyses of the two EAL motifs of DipA suggest that both are important for the observed phosphodiesterase activity and dispersion, while the GAF domain modulated DipA function bothin vivoandin vitrowithout being required for phosphodiesterase activity. Dispersion was found to require protein synthesis and resulted in increaseddipAexpression and reduction of c-di-GMP levels. We propose a role of DipA in enabling dispersion inP. aeruginosabiofilms.
Myxococcus xanthus Developmental Cell Fate Production: Heterogeneous Accumulation of Developmental Regulatory Proteins and Reexamination of the Role of MazF in Developmental Lysis
Authors: Lee Bongsoo , Holkenbrink Carina , Treuner-Lange Anke , Higgs Penelope I. 
Published: April 2012

ABSTRACT

Myxococcus xanthus
undergoes a starvation-induced multicellular developmental program during which cells partition into three known fates: (i) aggregation into fruiting bodies followed by differentiation into spores, (ii) lysis, or (iii) differentiation into nonaggregating persister-like cells, termed peripheral rods. As a first step to characterize cell fate segregation, we enumerated total, aggregating, and nonaggregating cells throughout the developmental program. We demonstrate that both cell lysis and cell aggregation begin with similar timing at approximately 24 h after induction of development. Examination of several known regulatory proteins in the separated aggregated and nonaggregated cell fractions revealed previously unknown heterogeneity in the accumulation patterns of proteins involved in type IV pilus (T4P)-mediated motility (PilC and PilA) and regulation of development (MrpC, FruA, and C-signal). As part of our characterization of the cell lysis fate, we set out to investigate the unorthodox MazF-MrpC toxin-antitoxin system which was previously proposed to induce programmed cell death (PCD). We demonstrate that deletion of
mazF
in two different wild-type
M. xanthus
laboratory strains does not significantly reduce developmental cell lysis, suggesting that MazF's role in promoting PCD is an adaption to the mutant background strain used previously.
The association between lung function and fatal stroke in a community followed for 4 decades
Authors: Gulsvik Anne Kristine , Gulsvik Amund , Skovlund Eva , Thelle Dag Steinar , Mowé Morten , Humerfelt Sjur , Wyller Torgeir Bruun 
Published: April 2012

BackgroundPrevious studies, all of <20 years of follow-up, have suggested an association between lung function and the risk of fatal stroke. This study investigates the stability of this association in a cohort followed for 4 decades.MethodsThe Bergen Clinical Blood Pressure Survey was conducted in Norway in 1964–1971. The risk of fatal stroke associated with forced expiratory volume after one second (FEV1) was estimated with Cox proportional hazards regression, making progressive adjustment for potential confounders.ResultsOf 5617 (84%) participants with recorded baseline FEV1, 462 died from stroke over 152 786 subsequent person-years of follow-up according to mortality statistics of 2005; mean (SD) follow-up was 27 (12) years. An association between baseline FEV1(L) and fatal stroke was observed; HR=1.38 (95% CI 1.11 to 1.71) and HR=1.62 (95% CI 1.22 to 2.15) for men and women, respectively (adjusted for age and height). The findings were not explained by smoking, hypertension, diabetes, atherosclerosis, socioeconomic status, obstructive lung disease, physical inactivity, cholesterol or body mass index and persisted in subgroups of never-smokers, subgroups without respiratory symptoms and survivors of the first 20 years of follow-up. For male survivors with a valid FEV1at follow-up (1988–1990) (n=953), baseline FEV1(L) indicated a possible strong and independent association to the risk of fatal stroke after adjustments for individual changes in FEV1(ml/year) (HR 1.95 (95% CI 0.98 to 3.86)).ConclusionThere is a consistent, independent and long-lasting association between lung function and fatal stroke, probably irrespective of changes during adult life.