bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effects of Heat Activation on Bacillus Spore Germination, with Nutrients or under High Pressure, with or without Various Germination Proteins
Authors: Luu Stephanie , Cruz-Mora Jose , Setlow Barbara , Feeherry Florence E. , Doona Christopher J. , Setlow Peter 
Published: February 2015

ABSTRACT

Nutrient germination of spores of
Bacillus
species occurs through germinant receptors (GRs) in spores' inner membrane (IM) in a process stimulated by sublethal heat activation.
Bacillus subtilis
spores maximum germination rates via different GRs required different 75°C heat activation times: 15 min for
l
-valine germination via the GerA GR and 4 h for germination with the
l
-asparagine–glucose–fructose–K
+
mixture via the GerB and GerK GRs, with GerK requiring the most heat activation. In some cases, optimal heat activation decreased nutrient concentrations for half-maximal germination rates. Germination of spores via various GRs by high pressure (HP) of 150 MPa exhibited heat activation requirements similar to those of nutrient germination, and the loss of the GerD protein, required for optimal GR function, did not eliminate heat activation requirements for maximal germination rates. These results are consistent with heat activation acting primarily on GRs. However, (i) heat activation had no effects on GR or GerD protein conformation, as probed by biotinylation by an external reagent; (ii) spores prepared at low and high temperatures that affect spores' IM properties exhibited large differences in heat activation requirements for nutrient germination; and (iii) spore germination by 550 MPa of HP was also affected by heat activation, but the effects were relatively GR independent. The last results are consistent with heat activation affecting spores' IM and only indirectly affecting GRs. The 150- and 550-MPa HP germinations of
Bacillus amyloliquefaciens
spores, a potential surrogate for
Clostridium botulinum
spores in HP treatments of foods, were also stimulated by heat activation.
Microbial Growth under Supercritical CO
2
Authors: Peet Kyle C. , Freedman Adam J. E. , Hernandez Hector H. , Britto Vanya , Boreham Chris , Ajo-Franklin Jonathan B. , Thompson Janelle R. 
Published: February 2015

ABSTRACT

Growth of microorganisms in environments containing CO
2
above its critical point is unexpected due to a combination of deleterious effects, including cytoplasmic acidification and membrane destabilization. Thus, supercritical CO
2
(scCO
2
) is generally regarded as a sterilizing agent. We report isolation of bacteria from three sites targeted for geologic carbon dioxide sequestration (GCS) that are capable of growth in pressurized bioreactors containing scCO
2
. Analysis of 16S rRNA genes from scCO
2
enrichment cultures revealed microbial assemblages of varied complexity, including representatives of the genus
Bacillus
. Propagation of enrichment cultures under scCO
2
headspace led to isolation of six strains corresponding to
Bacillus cereus
,
Bacillus subterraneus
,
Bacillus amyloliquefaciens
,
Bacillus safensis
, and
Bacillus megaterium
. Isolates are spore-forming, facultative anaerobes and capable of germination and growth under an scCO
2
headspace. In addition to these isolates, several
Bacillus
type strains grew under scCO
2
, suggesting that this may be a shared feature of spore-forming
Bacillus
spp. Our results provide direct evidence of microbial activity at the interface between scCO
2
and an aqueous phase. Since microbial activity can influence the key mechanisms for permanent storage of sequestered CO
2
(i.e., structural, residual, solubility, and mineral trapping), our work suggests that during GCS microorganisms may grow and catalyze biological reactions that influence the fate and transport of CO
2
in the deep subsurface.
The Peptide Toxin Amylosin of Bacillus amyloliquefaciens from Moisture-Damaged Buildings Is Immunotoxic, Induces Potassium Efflux from Mammalian Cells, and Has Antimicrobial Activity
Authors: Rasimus-Sahari Stiina , Teplova Vera V. , Andersson Maria A. , Mikkola Raimo , Kankkunen Päivi , Matikainen Sampsa , Gahmberg Carl G. , Andersson Leif C. , Salkinoja-Salonen Mirja 
Published: February 2015

ABSTRACTAmylosin, a heat-stable channel-forming non-ribosomally synthesized peptide toxin produced by strains ofBacillus amyloliquefaciensisolated from moisture-damaged buildings, is shown in this paper to have immunotoxic and cytotoxic effects on human cells as well as antagonistic effects on microbes. Human macrophages exposed to 50 ng of amylosin ml−1secreted high levels of cytokines interleukin-1β (IL-1β) and IL-18 within 2 h, indicating activation of the NLRP3 inflammasome, an integral part of the innate immune system. At the same exposure level, expression of IL-1β and IL-18 mRNA increased. Amylosin caused dose-dependent potassium ion efflux from all tested mammalian cells (human monocytes and keratinocytes and porcine sperm cells) at 1 to 2 μM exposure. Amylosin also inhibited the motility of porcine sperm cells and depolarized the mitochondria of human keratinocytes. Amylosin may thus trigger the activation of the NLRP3 inflammasome and subsequently cytokine release by causing potassium efflux from exposed cells. The results of this study indicate that exposure to amylosin activates the innate immune system, which could offer an explanation for the inflammatory symptoms experienced by occupants of moisture-damaged buildings. In addition, the amylosin-producingB. amyloliquefaciensinhibited the growth of both prokaryotic and eukaryotic indoor microbes, and purified amylosin also had an antimicrobial effect. These antimicrobial effects could make amylosin producers dominant and therefore significant causal agents of health problems in some moisture-damaged sites.
Quantitative PCR Analysis of Functional Genes in Iron-Rich Microbial Mats at an Active Hydrothermal Vent System (Lō'ihi Seamount, Hawai'i)
Authors: Jesser Kelsey J. , Fullerton Heather , Hager Kevin W. , Moyer Craig L. 
Published: February 2015

ABSTRACT

The chemolithotrophic
Zetaproteobacteria
represent a novel class of
Proteobacteria
which oxidize Fe(II) to Fe(III) and are the dominant bacterial population in iron-rich microbial mats.
Zetaproteobacteria
were first discovered at Lō'ihi Seamount, located 35 km southeast off the big island of Hawai'i, which is characterized by low-temperature diffuse hydrothermal venting. Novel nondegenerate quantitative PCR (qPCR) assays for genes associated with microbial nitrogen fixation, denitrification, arsenic detoxification, Calvin-Benson-Bassham (CBB), and reductive tricarboxylic acid (rTCA) cycles were developed using selected microbial mat community-derived metagenomes. Nitrogen fixation genes were not detected, but all other functional genes were present. This suggests that arsenic detoxification and denitrification processes are likely cooccurring in addition to two modes of carbon fixation. Two groups of microbial mat community types were identified by terminal restriction fragment length polymorphism (T-RFLP) and were further described based on qPCR data for zetaproteobacterial abundance and carbon fixation mode preference. qPCR variance was associated with mat morphology but not with temperature or sample site. Geochemistry data were significantly associated with sample site and mat morphology. Together, these qPCR assays constitute a functional gene signature for iron microbial mat communities across a broad array of temperatures, mat types, chemistries, and sampling sites at Lō'ihi Seamount.
Disparate Independent Genetic Events Disrupt the Secondary Metabolism Gene
perA
in Certain Symbiotic Epichloë Species
Authors: Berry Daniel , Takach Johanna E. , Schardl Christopher L. , Charlton Nikki D. , Scott Barry , Young Carolyn A. 
Published: February 2015

ABSTRACT

Peramine is an insect-feeding deterrent produced by
Epichloë
species in symbiotic association with C
3
grasses. The
perA
gene responsible for peramine synthesis encodes a two-module nonribosomal peptide synthetase. Alleles of
perA
are found in most
Epichloë
species; however, peramine is not produced by many
perA
-containing
Epichloë
isolates. The genetic basis of these peramine-negative chemotypes is often unknown. Using PCR and DNA sequencing, we analyzed the
perA
genes from 72
Epichloë
isolates and identified causative mutations of
perA
null alleles. We found nonfunctional
perA
-ΔR* alleles, which contain a transposon-associated deletion of the
perA
region encoding the C-terminal reductase domain, are widespread within the
Epichloë
genus and represent a prevalent mutation found in nonhybrid species. Disparate phylogenies of adjacent A2 and T2 domains indicated that the deletion of the reductase domain (R*) likely occurred once and early in the evolution of the genus, and subsequently there have been several recombinations between those domains. A number of novel point, deletion, and insertion mutations responsible for abolishing peramine production in full-length
perA
alleles were also identified. The regions encoding the first and second adenylation domains (A1 and A2, respectively) were common sites for such mutations. Using this information, a method was developed to predict peramine chemotypes by combining PCR product size polymorphism analysis with sequencing of the
perA
adenylation domains.
Mortality of Cutworm Larvae Is Not Enhanced by Agrotis segetum Granulovirus and Agrotis segetum Nucleopolyhedrovirus B Coinfection Relative to Single Infection by Either Virus
Authors: Wennmann Jörg T. , Köhler Tim , Gueli Alletti Gianpiero , Jehle Johannes A. 
Published: February 2015

ABSTRACT

Mixed infections of insect larvae with different baculoviruses are occasionally found. They are of interest from an evolutionary as well as from a practical point of view when baculoviruses are applied as biocontrol agents. Here, we report mixed-infection studies of neonate larvae of the common cutworm,
Agrotis segetum
, with two baculoviruses, Agrotis segetum nucleopolyhedrovirus B (AgseNPV-B) and Agrotis segetum granulovirus (AgseGV). By applying quantitative PCR (qPCR) analysis, coinfections of individual larvae were demonstrated, and occlusion body (OB) production within singly infected and coinfected larvae was determined in individual larvae. Mixtures of viruses did not lead to changes in mortality rates compared with rates of single-virus treatments, indicating an independent action within host larvae under our experimental conditions. AgseNPV-B-infected larvae showed an increase in OB production during 2 weeks of infection, whereas the number of AgseGV OBs did not change from the first week to the second week. Fewer OBs of both viruses were produced in coinfections than in singly infected larvae, suggesting a competition of the two viruses for larval resources. Hence, no functional or economic advantage could be inferred from larval mortality and OB production from mixed infections of
A. segetum
larvae with AgseNPV-B and AgseGV.
Community Dynamics of Arbuscular Mycorrhizal Fungi in High-Input and Intensively Irrigated Rice Cultivation Systems
Authors: Wang Yutao , Li Ting , Li Yingwei , Björn Lars Olof , Rosendahl Søren , Olsson Pål Axel , Li Shaoshan , Fu Xuelin 
Published: February 2015

ABSTRACT

Application of a mycorrhizal inoculum could be one way to increase the yield of rice plants and reduce the application of fertilizer. We therefore studied arbuscular mycorrhizal fungi (AMF) in the roots of wetland rice (
Oryza sativa
L.) collected at the seedling, tillering, heading, and ripening stages in four paddy wetlands that had been under a high-input and intensively irrigated rice cultivation system for more than 20 years. It was found that AMF colonization was mainly established in the heading and ripening stages. The AMF community structure was characterized in rhizosphere soils and roots from two of the studied paddy wetlands. A fragment covering the partial small subunit (SSU), the whole internal transcribed spacer (ITS), and the partial large subunit (LSU) rRNA operon regions of AMF was amplified, cloned, and sequenced from roots and soils. A total of 639 AMF sequences were obtained, and these were finally assigned to 16 phylotypes based on a phylogenetic analysis, including 12 phylotypes from
Glomeraceae
, one phylotype from
Claroideoglomeraceae
, two phylotypes from
Paraglomeraceae
, and one unidentified phylotype. The AMF phylotype compositions in the soils were similar between the two surveyed sites, but there was a clear discrepancy between the communities obtained from root and soil. The relatively high number of AMF phylotypes at the surveyed sites suggests that the conditions are suitable for some species of AMF and that they may have an important function in conventional rice cultivation systems. The species richness of root-colonizing AMF increased with the growth of rice, and future studies should consider the developmental stages of this crop in the exploration of AMF function in paddy wetlands.
Culture-Independent Evaluation of Nonenveloped-Virus Infectivity Reduced by Free-Chlorine Disinfection
Authors: Sano Daisuke , Ohta Takatomo , Nakamura Arata , Nakagomi Toyoko , Nakagomi Osamu , Okabe Satoshi 
Published: February 2015

ABSTRACT

The inability of molecular detection methods to distinguish disinfected virions from infectious ones has hampered the assessment of infectivity for enteric viruses caused by disinfection practices. In the present study, the reduction of infectivity of murine norovirus S7-PP3 and mengovirus vMC0, surrogates of human noroviruses and enteroviruses, respectively, caused by free-chlorine treatment was characterized culture independently by detecting carbonyl groups on viral capsid protein. The amount of carbonyls on viral capsid protein was evaluated by the proportion of biotinylated virions trapped by avidin-immobilized gel (percent adsorbed). This culture-independent approach demonstrated that the percent adsorbed was significantly correlated with the logarithm of the infectious titer of tested viruses. Taken together with the results of previous reports, the result obtained in this study indicates that the amount of carbonyls on viral capsid protein of four important families of waterborne pathogenic viruses,
Astroviridae
,
Reoviridae
,
Caliciviridae
, and
Picornaviridae
, is increased in proportion to the received oxidative stress of free chlorine. There was also a significant correlation between the percent adsorbed and the logarithm of the ratio of genome copy number to PFU, which enables estimation of the infectious titer of a subject virus by measuring values of the total genome copy number and the percent adsorbed. The proposed method is applicable when the validation of a 4-log reduction of viruses, a requirement in U.S. EPA guidelines for virus removal from water, is needed along with clear evidence of the oxidation of virus particles with chlorine-based disinfectants.
Arsenic Methylation and Volatilization by Arsenite
S
-Adenosylmethionine Methyltransferase in Pseudomonas alcaligenes NBRC14159
Authors: Zhang Jun , Cao Tingting , Tang Zhu , Shen Qirong , Rosen Barry P. , Zhao Fang-Jie 
Published: February 2015

ABSTRACT

Inorganic arsenic (As) is highly toxic and ubiquitous in the environment. Inorganic As can be transformed by microbial methylation, which constitutes an important part of the As biogeochemical cycle. In this study, we investigated As biotransformation by
Pseudomonas alcaligenes
NBRC14159.
P. alcaligenes
was able to methylate arsenite [As(III)] rapidly to dimethylarsenate and small amounts of trimethylarsenic oxide. An arsenite
S
-adenosylmethionine methyltransferase, PaArsM, was identified and functionally characterized. PaArsM shares low similarities with other reported ArsM enzymes (<55%). When
P. alcaligenes arsM
gene (
PaarsM
) was disrupted, the mutant lost As methylation ability and became more sensitive to As(III).
PaarsM
was expressed in the absence of As(III) and the expression was further enhanced by As(III) exposure. Heterologous expression of
PaarsM
in an As-hypersensitive strain of
Escherichia coli
conferred As(III) resistance. Purified PaArsM protein methylated As(III) to dimethylarsenate as the main product in the medium and also produced dimethylarsine and trimethylarsine gases. We propose that PaArsM plays a role in As methylation and detoxification of As(III) and could be exploited in bioremediation of As-contaminated environments.
The Host Plant Metabolite Glucose Is the Precursor of Diffusible Signal Factor (DSF) Family Signals in Xanthomonas campestris
Authors: Deng Yinyue , Liu Xiaoling , Wu Ji'en , Lee Jasmine , Chen Shaohua , Cheng Yingying , Zhang Chunyan , Zhang Lian-Hui 
Published: February 2015

ABSTRACT

Plant pathogen
Xanthomonas campestris
pv. campestris produces
cis
-11-methyl-2-dodecenoic acid (diffusible signal factor [DSF]) as a cell-cell communication signal to regulate biofilm dispersal and virulence factor production. Previous studies have demonstrated that DSF biosynthesis is dependent on the presence of RpfF, an enoyl-coenzyme A (CoA) hydratase, but the DSF synthetic mechanism and the influence of the host plant on DSF biosynthesis are still not clear. We show here that exogenous addition of host plant juice or ethanol extract to the growth medium of
X. campestris
pv. campestris could significantly boost DSF family signal production. It was subsequently revealed that
X. campestris
pv. campestris produces not only DSF but also BDSF (
cis
-2-dodecenoic acid) and another novel DSF family signal, which was designated DSF-II. BDSF was originally identified in
Burkholderia cenocepacia
to be involved in regulation of motility, biofilm formation, and virulence in
B. cenocepacia
. Functional analysis suggested that DSF-II plays a role equal to that of DSF in regulation of biofilm dispersion and virulence factor production in
X. campestris
pv. campestris. Furthermore, chromatographic separation led to identification of glucose as a specific molecule stimulating DSF family signal biosynthesis in
X. campestris
pv. campestris.
13
C-labeling experiments demonstrated that glucose acts as a substrate to provide a carbon element for DSF biosynthesis. The results of this study indicate that
X. campestris
pv. campestris could utilize a common metabolite of the host plant to enhance DSF family signal synthesis and therefore promote virulence.
Efficacy and Mechanisms of Murine Norovirus Inhibition by Pulsed-Light Technology
Authors: Vimont Allison , Fliss Ismaïl , Jean Julie 
Published: February 2015

ABSTRACT

Pulsed light is a nonthermal processing technology recognized by the FDA for killing microorganisms on food surfaces, with cumulative fluences up to 12 J cm
−2
. In this study, we investigated its efficacy for inactivating murine norovirus 1 (MNV-1) as a human norovirus surrogate in phosphate-buffered saline, hard water, mineral water, turbid water, and sewage treatment effluent and on food contact surfaces, including high-density polyethylene, polyvinyl chloride, and stainless steel, free or in an alginate matrix. The pulsed-light device emitted a broadband spectrum (200 to 1,000 nm) at a fluence of 0.67 J cm
−2
per pulse, with 2% UV at 8 cm beneath the lamp. Reductions in viral infectivity exceeded 3 log
10
in less than 3 s (5 pulses; 3.45 J cm
−2
) in clear suspensions and on clean surfaces, even in the presence of alginate, and in 6 s (11 pulses; 7.60 J cm
−2
) on fouled surfaces except for stainless steel (2.6 log
10
). The presence of protein or bentonite interfered with viral inactivation. Analysis of the morphology, the viral proteins, and the RNA integrity of treated MNV-1 allowed us to elucidate the mechanisms involved in the antiviral activity of pulsed light. Pulsed light appeared to disrupt MNV-1 structure and degrade viral protein and RNA. The results suggest that pulsed-light technology could provide an effective alternative means of inactivating noroviruses in wastewaters, in clear beverages, in drinking water, or on food-handling surfaces in the presence or absence of biofilms.
Exploring the Enantioselective Mechanism of Halohydrin Dehalogenase from Agrobacterium radiobacter AD1 by Iterative Saturation Mutagenesis
Authors: Guo Chao , Chen Yanpu , Zheng Yu , Zhang Wei , Tao Yunwen , Feng Juan , Tang Lixia 
Published: February 2015

ABSTRACT

Halohydrin dehalogenase from
Agrobacterium radiobacter
AD1 (HheC) shows great potential in producing valuable chiral epoxides and β-substituted alcohols. The wild-type (WT) enzyme displays a high
R
-enantiopreference toward most aromatic substrates, whereas no
S
-selective HheC has been reported to date. To obtain more enantioselective enzymes, seven noncatalytic active-site residues were subjected to iterative saturation mutagenesis (ISM). After two rounds of screening aspects of both activity and enantioselectivity (
E
), three outstanding mutants (Thr134Val/Leu142Met, Leu142Phe/Asn176His, and Pro84Val/Phe86Pro/Thr134Ala/Asn176Ala mutants) with divergent enantioselectivity were obtained. The two double mutants displayed approximately 2-fold improvement in
R
-enantioselectivity toward 2-chloro-1-phenylethanol (2-CPE) without a significant loss of enzyme activity compared with the WT enzyme. Strikingly, the Pro84Val/Phe86Pro/Thr134Ala/Asn176Ala mutant showed an inverted enantioselectivity (from an

E
R

of 65 [WT] to an

E
S

of 101) and approximately 100-fold-enhanced catalytic efficiency toward (
S
)-2-CPE. Molecular dynamic simulation and docking analysis revealed that the phenyl side chain of (
S
)-2-CPE bound at a different location than that of its
R
-counterpart; those mutations generated extra connections for the binding of the favored enantiomer, while the eliminated connections reduced binding of the nonfavored enantiomer, all of which could contribute to the observed inverted enantiopreference.
TonB-Dependent Heme Iron Acquisition in the Tsetse Fly Symbiont Sodalis glossinidius
Authors: Hrusa Gili , Farmer William , Weiss Brian L. , Applebaum Taylor , Roma Jose Santinni , Szeto Lauren , Aksoy Serap , Runyen-Janecky Laura J. 
Published: February 2015

ABSTRACTSodalis glossinidiusis an intra- and extracellular symbiont of the tsetse fly (Glossinasp.), which feeds exclusively on vertebrate blood.S. glossinidiusresides in a wide variety of tsetse tissues and may encounter environments that differ dramatically in iron content. TheSodalischromosome encodes a putative TonB-dependent outer membrane heme transporter (HemR) and a putative periplasmic/inner membrane ABC heme permease system (HemTUV). Because these gene products mediate iron acquisition processes by other enteric bacteria, we characterized their regulation and physiological role in theSodalis/tsetse system. Our results show that thehemRandtonBgenes are expressed byS. glossinidiusin the tsetse fly. Furthermore, transcription ofhemRinSodalisis repressed in a high-iron environment by the iron-responsive transcriptional regulator Fur. Expression of theS. glossinidiushemRandhemTUVgenes in anEscherichia colistrain unable to use heme as an iron source stimulated growth in the presence of heme or hemoglobin as the sole iron source. This stimulation was dependent on the presence of either theE. coliorSodalistonBgene.SodalistonBandhemRmutant strains were defective in their ability to colonize the gut of tsetse flies that lacked endogenous symbionts, while wild-typeS. glossinidiusproliferated in this same environment. Finally, we show that theSodalisHemR protein is localized to the bacterial membrane and appears to bind hemin. Collectively, this study provides strong evidence that TonB-dependent, HemR-mediated iron acquisition is important for the maintenance of symbiont homeostasis in the tsetse fly, and it provides evidence for the expression of bacterial high-affinity iron acquisition genes in insect symbionts.