bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reaerosolization of Spores from Flooring Surfaces To Assess the Risk of Dissemination and Transmission of Infections
Authors: Paton Susan , Thompson Katy-Anne , Parks Simon R. , Bennett Allan M. 
Published: May 2015

ABSTRACT

The aim of this study was to quantify reaerosolization of microorganisms caused by walking on contaminated flooring to assess the risk to individuals accessing areas contaminated with pathogenic organisms, for example, spores of
Bacillus anthracis
. Industrial carpet and polyvinyl chloride (PVC) floor coverings were contaminated with aerosolized spores of
Bacillus atrophaeus
by using an artist airbrush to produce deposition of ∼10
3
to 10
4
CFU · cm
−2
. Microbiological air samplers were used to quantify the particle size distribution of the aerosol generated when a person walked over the floorings in an environmental chamber. Results were expressed as reaerosolization factors (percent per square centimeter per liter), to represent the ratio of air concentration to surface concentration generated. Walking on carpet generated a statistically significantly higher reaerosolization factor value than did walking on PVC (
t
= 20.42;
P
< 0.001). Heavier walking produced a statistically significantly higher reaerosolization factor value than did lighter walking (
t
= 12.421;
P
< 0.001). Height also had a statistically significant effect on the reaerosolization factor, with higher rates of recovery of
B. atrophaeus
at lower levels, demonstrating a height-dependent gradient of particle reaerosolization. Particles in the respirable size range were recovered in all sampling scenarios (mass mean diameters ranged from 2.6 to 4.1 μm). The results of this study can be used to produce a risk assessment of the potential aerosol exposure of a person accessing areas with contaminated flooring in order to inform the choice of appropriate respiratory protective equipment and may aid in the selection of the most suitable flooring types for use in health care environments, to reduce aerosol transmission in the event of contamination.
Involvement of Colonizing Bacillus Isolates in Glucovanillin Hydrolysis during the Curing of Vanilla planifolia Andrews
Authors: Chen Yonggan , Gu Fenglin , Li Jihua , He Shuzhen , Xu Fei , Fang Yiming 
Published: May 2015

ABSTRACT

Vanilla beans were analyzed using biochemical methods, which revealed that glucovanillin disperses from the inner part to the outer part of the vanilla bean during the curing process and is simultaneously hydrolyzed by β-
d
-glucosidase. Enzymatic hydrolysis was found to occur on the surface of the vanilla beans. Transcripts of the β-
d
-glucosidase gene (
bgl
) of colonizing microorganisms were detected. The results directly indicate that colonizing microorganisms are involved in glucovanillin hydrolysis. Phylogenetic analysis based on 16S rRNA gene sequences showed that the colonizing microorganisms mainly belonged to the
Bacillus
genus.
bgl
was detected in all the isolates and presented clustering similar to that of the isolate taxonomy. Furthermore, inoculation of green fluorescent protein-tagged isolates showed that the
Bacillus
isolates can colonize vanilla beans. Glucovanillin was metabolized as the sole source of carbon in a culture of the isolates within 24 h. These isolates presented unique glucovanillin degradation capabilities. Vanillin was the major volatile compound in the culture. Other compounds, such as α-cubebene, β-pinene, and guaiacol, were detected in some isolate cultures. Colonizing
Bacillus
isolates were found to hydrolyze glucovanillin in culture, indirectly demonstrating the involvement of colonizing
Bacillus
isolates in glucovanillin hydrolysis during the vanilla curing process. Based on these results, we conclude that colonizing
Bacillus
isolates produce β-
d
-glucosidase, which mediates glucovanillin hydrolysis and influences flavor formation.
Wastewater Analysis Indicates that Genetically Diverse Astroviruses, Including Strains Belonging to Novel Clades MLB and VA, Are Circulating within Japanese Populations
Authors: Hata Akihiko , Katayama Hiroyuki , Kitajima Masaaki , Furumai Hiroaki 
Published: May 2015

ABSTRACTHuman astroviruses (HAstVs) are a common etiological agent of infantile gastroenteritis. Recent studies revealed that novel astrovirus (AstV) strains of the MLB clade (MLB-AstVs) and VA clade (VA-AstVs), which are genetically distinct from the classic HAstVs, are circulating in the human population. In the present study, we quantified classic HAstVs as well as carried out a genetic analysis of classic and novel HAstVs in wastewater in Japan. The concentration of classic HAstVs in the influent water samples ranged from 104to 105copies per liter, and the amount removed by wastewater treatment was determined to be 2.4 ± 0.3 log10. Four types of classic HAstV strains (HAstV types 1, 2, 5, and 4/8) as well as novel AstV strains belonging to the MLB-2, VA-1, and VA-2 clades were identified using reverse transcription-PCR (RT-PCR) assays, including assays newly developed for the detection of strains of the MLB and VA clades, followed by cloning and nucleotide sequencing. Our results suggest that genetically diverse AstV strains are circulating among the human population in Japan. The newly developed (semi)nested RT-PCR assays for these novel AstV clades are useful to identify and characterize the novel AstVs in environmental waters.
Chromosome-Directed PCR-Based Detection and Quantification of Bacillus cereus Group Members with Focus on B. thuringiensis Serovar israelensis Active against Nematoceran Larvae
Authors: Schneider Salome , Hendriksen Niels B. , Melin Petter , Lundström Jan O. , Sundh Ingvar 
Published: May 2015

ABSTRACT

Bacillus thuringiensis
serovar israelensis is a wide-spread soil bacterium affiliated with the
B. cereus
group (Bcg) and is widely used in biocontrol products applied against mosquito and black fly larvae. For monitoring and quantification of applied
B. thuringiensis
serovar israelensis and its effect on indigenous
B. thuringiensis
serovar israelensis and Bcg assemblages, efficient and reliable tools are essential. The abundance and properties of
B. thuringiensis
serovar israelensis strains in the environment traditionally have been investigated with cultivation-dependent techniques, which are hampered by low sensitivity and the morphological similarity between
B. cereus
and
B. thuringiensis
. Currently available PCR-based detection and quantification tools target markers located on plasmids. In this study, a new cultivation-independent PCR-based method for efficient and specific quantification of
B. thuringiensis
serovar israelensis and Bcg is presented, utilizing two sets of PCR primers targeting the bacterial chromosome. Sequence database searches and empirical tests performed on target and nontarget species, as well as on bulk soil DNA samples, demonstrated that this diagnostic tool is specific for
B. thuringiensis
serovar israelensis and Bcg. The method will be useful for comparisons of Bcg and
B. thuringiensis
serovar israelensis abundances in the same samples. Moreover, the effect of
B. thuringiensis
serovar israelensis-based insecticide application on the total Bcg assemblages, including indigenous populations, can be investigated. This type of information is valuable in risk assessment and policy making for use of
B. thuringiensis
serovar israelensis in the environment.
Microbiota at Multiple Body Sites during Pregnancy in a Rural Tanzanian Population and Effects of Moringa-Supplemented Probiotic Yogurt
Authors: Bisanz Jordan E. , Enos Megan K. , PrayGod George , Seney Shannon , Macklaim Jean M. , Chilton Stephanie , Willner Dana , Knight Rob , Fusch Christoph , Fusch Gerhard , Gloor Gregory B. , Burton Jeremy P. , Reid Gregor 
Published: May 2015

ABSTRACT

The nutritional status of pregnant women is vital for healthy outcomes and is a concern for a large proportion of the world's population. The role of the microbiota in pregnancy and nutrition is a promising new area of study with potential health ramifications. In many African countries, maternal and infant death and morbidity are associated with malnutrition. Here, we assess the influence of probiotic yogurt containing
Lactobacillus rhamnosus
GR-1, supplemented with Moringa plant as a source of micronutrients, on the health and oral, gut, vaginal, and milk microbiotas of 56 pregnant women in Tanzania. In an open-label study design, 26 subjects received yogurt daily, and 30 were untreated during the last two trimesters and for 1 month after birth. Samples were analyzed using 16S rRNA gene sequencing, and dietary recalls were recorded. Women initially categorized as nourished or undernourished consumed similar calories and macronutrients, which may explain why there was no difference in the microbiota at any body site. Consumption of yogurt increased the relative abundance of
Bifidobacterium
and decreased
Enterobacteriaceae
in the newborn feces but had no effect on the mother's microbiota at any body site. The microbiota of the oral cavity and GI tract remained stable over pregnancy, but the vaginal microbiota showed a significant increase in diversity leading up to and after birth. In summary, daily micronutrient-supplemented probiotic yogurt provides a safe, affordable food for pregnant women in rural Tanzania, and the resultant improvement in the gut microbial profile of infants is worthy of further study.
Comparative Analysis of Denitrifying Activities of Hyphomicrobium nitrativorans, Hyphomicrobium denitrificans, and Hyphomicrobium zavarzinii
Authors: Martineau Christine , Mauffrey Florian , Villemur Richard 
Published: May 2015

ABSTRACT

Hyphomicrobium
spp. are commonly identified as major players in denitrification systems supplied with methanol as a carbon source. However, denitrifying
Hyphomicrobium
species are poorly characterized, and very few studies have provided information on the genetic and physiological aspects of denitrification in pure cultures of these bacteria. This is a comparative study of three denitrifying
Hyphomicrobium
species,
H. denitrificans
ATCC 51888,
H. zavarzinii
ZV622, and a newly described species,
H. nitrativorans
NL23, which was isolated from a denitrification system treating seawater. Whole-genome sequence analyses revealed that although they share numerous orthologous genes, these three species differ greatly in their nitrate reductases, with gene clusters encoding a periplasmic nitrate reductase (Nap) in
H. nitrativorans
, a membrane-bound nitrate reductase (Nar) in
H. denitrificans
, and one Nap and two Nar enzymes in
H. zavarzinii
. Concurrently with these differences observed at the genetic level, important differences in the denitrification capacities of these
Hyphomicrobium
species were determined.
H. nitrativorans
grew and denitrified at higher nitrate and NaCl concentrations than did the two other species, without significant nitrite accumulation. Significant increases in the relative gene expression levels of the nitrate (
napA
) and nitrite (
nirK
) reductase genes were also noted for
H. nitrativorans
at higher nitrate and NaCl concentrations. Oxygen was also found to be a strong regulator of denitrification gene expression in both
H. nitrativorans
and
H. zavarzinii
, although individual genes responded differently in these two species. Taken together, the results presented in this study highlight the potential of
H. nitrativorans
as an efficient and adaptable bacterium that is able to perform complete denitrification under various conditions.
Molybdenum Availability Is Key to Nitrate Removal in Contaminated Groundwater Environments
Authors: Thorgersen Michael P. , Lancaster W. Andrew , Vaccaro Brian J. , Poole Farris L. , Rocha Andrea M. , Mehlhorn Tonia , Pettenato Angelica , Ray Jayashree , Waters R. Jordan , Melnyk Ryan A. , Chakraborty Romy , Hazen Terry C. , Deutschbauer Adam M. , Arkin Adam P. , Adams Michael W. W. 
Published: May 2015

ABSTRACT

The concentrations of molybdenum (Mo) and 25 other metals were measured in groundwater samples from 80 wells on the Oak Ridge Reservation (ORR) (Oak Ridge, TN), many of which are contaminated with nitrate, as well as uranium and various other metals. The concentrations of nitrate and uranium were in the ranges of 0.1 μM to 230 mM and <0.2 nM to 580 μM, respectively. Almost all metals examined had significantly greater median concentrations in a subset of wells that were highly contaminated with uranium (≥126 nM). They included cadmium, manganese, and cobalt, which were 1,300- to 2,700-fold higher. A notable exception, however, was Mo, which had a lower median concentration in the uranium-contaminated wells. This is significant, because Mo is essential in the dissimilatory nitrate reduction branch of the global nitrogen cycle. It is required at the catalytic site of nitrate reductase, the enzyme that reduces nitrate to nitrite. Moreover, more than 85% of the groundwater samples contained less than 10 nM Mo, whereas concentrations of 10 to 100 nM Mo were required for efficient growth by nitrate reduction for two
Pseudomonas
strains isolated from ORR wells and by a model denitrifier,
Pseudomonas stutzeri
RCH2. Higher concentrations of Mo tended to inhibit the growth of these strains due to the accumulation of toxic concentrations of nitrite, and this effect was exacerbated at high nitrate concentrations. The relevance of these results to a Mo-based nitrate removal strategy and the potential community-driving role that Mo plays in contaminated environments are discussed.
Diversity of the Sediment Microbial Community in the Aha Watershed (Southwest China) in Response to Acid Mine Drainage Pollution Gradients
Authors: Sun Weimin , Xiao Tangfu , Sun Min , Dong Yiran , Ning Zengping , Xiao Enzong , Tang Song , Li Jiwei 
Published: May 2015

ABSTRACT

Located in southwest China, the Aha watershed is continually contaminated by acid mine drainage (AMD) produced from upstream abandoned coal mines. The watershed is fed by creeks with elevated concentrations of aqueous Fe (total Fe > 1 g/liter) and SO
4
2−
(>6 g/liter). AMD contamination gradually decreases throughout downstream rivers and reservoirs, creating an AMD pollution gradient which has led to a suite of biogeochemical processes along the watershed. In this study, sediment samples were collected along the AMD pollution sites for geochemical and microbial community analyses. High-throughput sequencing found various bacteria associated with microbial Fe and S cycling within the watershed and AMD-impacted creek. A large proportion of Fe- and S-metabolizing bacteria were detected in this watershed. The dominant Fe- and S-metabolizing bacteria were identified as microorganisms belonging to the genera
Metallibacterium
,
Aciditerrimonas
,
Halomonas
,
Shewanella
,
Ferrovum
,
Alicyclobacillus
, and
Syntrophobacter
. Among them,
Halomonas
,
Aciditerrimonas
,
Metallibacterium
, and
Shewanella
have previously only rarely been detected in AMD-contaminated environments. In addition, the microbial community structures changed along the watershed with different magnitudes of AMD pollution. Moreover, the canonical correspondence analysis suggested that temperature, pH, total Fe, sulfate, and redox potentials (E
h
) were significant factors that structured the microbial community compositions along the Aha watershed.
Identification of GH15 Family Thermophilic Archaeal Trehalases That Function within a Narrow Acidic-pH Range
Authors: Sakaguchi Masayoshi , Shimodaira Satoru , Ishida Shin-nosuke , Amemiya Miko , Honda Shotaro , Sugahara Yasusato , Oyama Fumitaka , Kawakita Masao 
Published: May 2015

ABSTRACT

Two glucoamylase-like genes,
TVN1315
and
Ta0286
, from the archaea
Thermoplasma volcanium
and
T. acidophilum
, respectively, were expressed in
Escherichia coli
. The gene products, TVN1315 and Ta0286, were identified as archaeal trehalases. These trehalases belong to the CAZy database family GH15, although they have putative (α/α)
6
barrel catalytic domain structures similar to those of GH37 and GH65 family trehalases from other organisms. These newly identified trehalases function within a narrow range of acidic pH values (pH 3.2 to 4.0) and at high temperatures (50 to 60°C), and these enzymes display

K
m

values for trehalose higher than those observed for typical trehalases. These enzymes were inhibited by validamycin A; however, the inhibition constants (

K
i

) were higher than those of other trehalases. Three TVN1315 mutants, corresponding to E408Q, E571Q, and E408Q/E571Q mutations, showed reduced activity, suggesting that these two glutamic acid residues are involved in trehalase catalysis in a manner similar to that of glucoamylase. To date, TVN1315 and Ta0286 are the first archaeal trehalases to be identified, and this is the first report of the heterologous expression of GH15 family trehalases. The identification of these trehalases could extend our understanding of the relationships between the structure and function of GH15 family enzymes as well as glycoside hydrolase family enzymes; additionally, these enzymes provide insight into archaeal trehalose metabolism.
A Versatile Family 3 Glycoside Hydrolase from Bifidobacterium adolescentis Hydrolyzes β-Glucosides of the Fusarium Mycotoxins Deoxynivalenol, Nivalenol, and HT-2 Toxin in Cereal Matrices
Authors: Michlmayr Herbert , Varga Elisabeth , Malachova Alexandra , Nguyen Nhung Thi , Lorenz Cindy , Haltrich Dietmar , Berthiller Franz , Adam Gerhard 
Published: May 2015

ABSTRACT

Glycosylation plays a central role in plant defense against xenobiotics, including mycotoxins. Glucoconjugates of
Fusarium
toxins, such as deoxynivalenol-3-
O
-β-
d
-glucoside (DON-3G), often cooccur with their parental toxins in cereal-based food and feed. To date, only limited information exists on the occurrence of glucosylated mycotoxins and their toxicological relevance. Due to a lack of analytical standards and the requirement of high-end analytical instrumentation for their direct determination, hydrolytic cleavage of β-glucosides followed by analysis of the released parental toxins has been proposed as an indirect determination approach. This study compares the abilities of several fungal and recombinant bacterial β-glucosidases to hydrolyze the model analyte DON-3G. Furthermore, substrate specificities of two fungal and two bacterial (
Lactobacillus brevis
and
Bifidobacterium adolescentis
) glycoside hydrolase family 3 β-glucosidases were evaluated on a broader range of substrates. The purified recombinant enzyme from
B. adolescentis
(
Ba
Bgl) displayed high flexibility in substrate specificity and exerted the highest hydrolytic activity toward 3-
O
-β-
d
-glucosides of the trichothecenes deoxynivalenol (DON), nivalenol, and HT-2 toxin. A

K
m

of 5.4 mM and a
V
max
of 16 μmol min
−1
mg
−1
were determined with DON-3G. Due to low product inhibition (DON and glucose) and sufficient activity in several extracts of cereal matrices, this enzyme has the potential to be used for indirect analyses of trichothecene-β-glucosides in cereal samples.
Genetics and Physiology of Acetate Metabolism by the Pta-Ack Pathway of Streptococcus mutans
Authors: Kim Jeong Nam , Ahn Sang-Joon , Burne Robert A. 
Published: May 2015

ABSTRACT

In the dental caries pathogen
Streptococcus mutans
, phosphotransacetylase (Pta) catalyzes the conversion of acetyl coenzyme A (acetyl-CoA) to acetyl phosphate (AcP), which can be converted to acetate by acetate kinase (Ack), with the concomitant generation of ATP. A Δ
ackA
mutant displayed enhanced accumulation of AcP under aerobic conditions, whereas little or no AcP was observed in the Δ
pta
or Δ
pta
Δ
ackA
mutant. The Δ
pta
and Δ
pta
Δ
ackA
mutants also had diminished ATP pools compared to the size of the ATP pool for the parental or Δ
ackA
strain. Surprisingly, when exposed to oxidative stress, the Δ
pta
Δ
ackA
strain appeared to regain the capacity to produce AcP, with a concurrent increase in the size of the ATP pool compared to that for the parental strain. The Δ
ackA
and Δ
pta
Δ
ackA
mutants exhibited enhanced (p)ppGpp accumulation, whereas the strain lacking Pta produced less (p)ppGpp than the wild-type strain. The Δ
ackA
and Δ
pta
Δ
ackA
mutants displayed global changes in gene expression, as assessed by microarrays. All strains lacking Pta, which had defects in AcP production under aerobic conditions, were impaired in their abilities to form biofilms when glucose was the growth carbohydrate. Collectively, these data demonstrate the complex regulation of the Pta-Ack pathway and critical roles for these enzymes in processes that appear to be essential for the persistence and pathogenesis of
S. mutans
.
Oxalobacter formigenes Colonization and Oxalate Dynamics in a Mouse Model
Authors: Li Xingsheng , Ellis Melissa L. , Knight John 
Published: May 2015

ABSTRACT

Animal and human studies have provided compelling evidence that colonization of the intestine with
Oxalobacter formigenes
reduces urinary oxalate excretion and lowers the risk of forming calcium oxalate kidney stones. The mechanism providing protection appears to be related to the unique ability of
O. formigenes
to rely on oxalate as a major source of carbon and energy for growth. However, much is not known about the factors that influence colonization and host-bacterium interactions. We have colonized mice with
O. formigenes
OxCC13 and systematically investigated the impacts of diets with different levels of calcium and oxalate on
O. formigenes
intestinal densities and urinary and intestinal oxalate levels. Measurement of intestinal oxalate levels in mice colonized or not colonized with
O. formigenes
demonstrated the highly efficient degradation of soluble oxalate by
O. formigenes
relative to other microbiota. The ratio of calcium to oxalate in diets was important in determining colonization densities and conditions where urinary oxalate and fecal oxalate excretion were modified, and the results were consistent with those from studies we have performed with colonized and noncolonized humans. The use of low-oxalate purified diets showed that 80% of animals retained
O. formigenes
colonization after a 1-week dietary oxalate deprivation. Animals not colonized with
O. formigenes
excreted two times more oxalate in feces than they had ingested. This nondietary source of oxalate may play an important role in the survival of
O. formigenes
during periods of dietary oxalate deprivation. These studies suggest that the mouse will be a useful model to further characterize interactions between
O. formigenes
and the host and factors that impact colonization.