bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Various Ions, pH, and Osmotic Pressure on Oxidation of Elemental Sulfur by
Thiobacillus thiooxidans
Authors: Suzuki Isamu , Lee Douglas , Mackay Byron , Harahuc Lesia , Oh Jae Key 
Published: December 2019

ABSTRACT

The oxidation of elemental sulfur by
Thiobacillus thiooxidans
was studied at pH 2.3, 4.5, and 7.0 in the presence of different concentrations of various anions (sulfate, phosphate, chloride, nitrate, and fluoride) and cations (potassium, sodium, lithium, rubidium, and cesium). The results agree with the expected response of this acidophilic bacterium to charge neutralization of colloids by ions, pH-dependent membrane permeability of ions, and osmotic pressure.
Long-Term Survival of Shiga Toxin-Producing
Escherichia coli
O26, O111, and O157 in Bovine Feces
Authors: Fukushima Hiroshi , Hoshina Ken , Gomyoda Manabu 
Published: December 2019

ABSTRACT

Cattle are an important reservoir of Shiga toxin-producing
Escherichia coli
(STEC) O26, O111, and O157. The fate of these pathogens in bovine feces at 5, 15, and 25°C was examined. The feces of a cow naturally infected with STEC O26:H11 and two STEC-free cows were studied. STEC O26, O111, and O157 were inoculated into bovine feces at 10
1
, 10
3
, and 10
5
CFU/g. All three pathogens survived at 5 and 25°C for 1 to 4 weeks and at 15°C for 1 to 8 weeks when inoculated at the low concentration. On samples inoculated with the middle and high concentrations, O26, O111, and O157 survived at 25°C for 3 to 12 weeks, at 15°C for 1 to 18 weeks, and at 5°C for 2 to 14 weeks, respectively. Therefore, these pathogens can survive in feces for a long time, especially at 15°C. The surprising long-term survival of STEC O26, O111, and O157 in bovine feces shows that such feces are a potential vehicle for transmitting not only O157 but also O26 and O111 to cattle, food, and the environment. Appropriate handling of bovine feces is emphasized.
Fungi from Geothermal Soils in Yellowstone National Park
Authors: Redman Regina S. , Litvintseva Anastassia , Sheehan Kathy B. , Henson Joan M. , Rodriguez Rusty J. 
Published: December 2019

ABSTRACTGeothermal soils near Amphitheater Springs in Yellowstone National Park were characterized by high temperatures (up to 70°C), high heavy metal content, low pH values (down to pH 2.7), sparse vegetation, and limited organic carbon. From these soils we cultured 16 fungal species. Two of these species were thermophilic, and six were thermotolerant. We cultured only three of these species from nearby cool (0 to 22°C) soils. Transect studies revealed that higher numbers of CFUs occurred in and below the root zone of the perennial plantDichanthelium lanuginosum(hot springs panic grass). The dynamics of fungal CFUs in geothermal soil and nearby nongeothermal soil were investigated for 12 months by examining soil cores and in situ mesocosms. For all of the fungal species studied, the temperature of the soil from which the organisms were cultured corresponded with their optimum axenic growth temperature.
Removal of Mercury from Chloralkali Electrolysis Wastewater by a Mercury-Resistant
Pseudomonas putida
Strain
Authors: von Canstein H. , Li Y. , Timmis K. N. , Deckwer W.-D. , Wagner-Döbler I. 
Published: December 2019

ABSTRACT

A mercury-resistant bacterial strain which is able to reduce ionic mercury to metallic mercury was used to remediate in laboratory columns mercury-containing wastewater produced during electrolytic production of chlorine. Factory effluents from several chloralkali plants in Europe were analyzed, and these effluents contained total mercury concentrations between 1.6 and 7.6 mg/liter and high chloride concentrations (up to 25 g/liter) and had pH values which were either acidic (pH 2.4) or alkaline (pH 13.0). A mercury-resistant bacterial strain,
Pseudomonas putida
Spi3, was isolated from polluted river sediments. Biofilms of
P. putida
Spi3 were grown on porous carrier material in laboratory column bioreactors. The bioreactors were continuously fed with sterile synthetic model wastewater or nonsterile, neutralized, aerated chloralkali wastewater. We found that sodium chloride concentrations up to 24 g/liter did not inhibit microbial mercury retention and that mercury concentrations up to 7 mg/liter could be treated with the bacterial biofilm with no loss of activity. When wastewater samples from three different chloralkali plants in Europe were used, levels of mercury retention efficiency between 90 and 98% were obtained. Thus, microbial mercury removal is a potential biological treatment for chloralkali electrolysis wastewater.
Lignin-Modifying Enzymes of the White Rot Basidiomycete
Ganoderma lucidum
Authors: D’Souza Trevor M. , Merritt Carlos S. , Reddy C. Adinarayana 
Published: December 2019

ABSTRACT

Ganoderma lucidum
, a white rot basidiomycete widely distributed worldwide, was studied for the production of the lignin-modifying enzymes laccase, manganese-dependent peroxidase (MnP), and lignin peroxidase (LiP). Laccase levels observed in high-nitrogen (HN; 24 mM N) shaken cultures were much greater than those seen in low-nitrogen (2.4 mM N), malt extract, or wood-grown cultures and those reported for most other white rot fungi to date. Laccase production was readily seen in cultures grown with pine or poplar (100-mesh-size ground wood) as the sole carbon and energy source. Cultures containing both pine and poplar showed 5- to 10-fold-higher levels of laccase than cultures containing pine or poplar alone. Since syringyl units are structural components important in poplar lignin and other hardwoods but much less so in pine lignin and other softwoods, pine cultures were supplemented with syringic acid, and this resulted in laccase levels comparable to those seen in pine-plus-poplar cultures. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of concentrated extracellular culture fluid from HN cultures showed two laccase activity bands (
M
r
of 40,000 and 66,000), whereas isoelectric focusing revealed five major laccase activity bands with estimated pIs of 3.0, 4.25, 4.5, 4.8, and 5.1. Low levels of MnP activity (∼100 U/liter) were detected in poplar-grown cultures but not in cultures grown with pine, with pine plus syringic acid, or in HN medium. No LiP activity was seen in any of the media tested; however, probing the genomic DNA with the LiP cDNA (
CLG4
) from the white rot fungus
Phanerochaete chrysosporium
showed distinct hybridization bands suggesting the presence of
lip
-like sequences in
G. lucidum
.
Listeria monocytogenes
Scott A: Cell Surface Charge, Hydrophobicity, and Electron Donor and Acceptor Characteristics under Different Environmental Growth Conditions
Authors: Briandet Romain , Meylheuc Thierry , Maher Catherine , Bellon-Fontaine Marie Noëlle 
Published: December 2019

ABSTRACT

We determined the variations in the surface physicochemical properties of
Listeria monocytogenes
Scott A cells that occurred under various environmental conditions. The surface charges, the hydrophobicities, and the electron donor and acceptor characteristics of
L. monocytogenes
Scott A cells were compared after the organism was grown in different growth media and at different temperatures; to do this, we used microelectrophoresis and the microbial adhesion to solvents method. Supplementing the growth media with glucose or lactic acid affected the electrical, hydrophobic, and electron donor and acceptor properties of the cells, whereas the growth temperature (37, 20, 15, or 8°C) primarily affected the electrical and electron donor and acceptor properties. The nonlinear effects of the growth temperature on the physicochemical properties of the cells were similar for cells cultivated in two different growth media, but bacteria cultivated in Trypticase soy broth supplemented with 6 g of yeast extract per liter (TSYE) were slightly more hydrophobic than cells cultivated in brain heart infusion medium (
P
< 0.05). Adhesion experiments conducted with
L. monocytogenes
Scott A cells cultivated in TSYE at 37, 20, 15, and 8°C and then suspended in a sodium chloride solution (1.5 × 10
−1
or 1.5 × 10
−3
M NaCl) confirmed that the cell surface charge and the electron donor and acceptor properties of the cells had an influence on their attachment to stainless steel.
Agar Underlay Method for Recovery of Sublethally Heat-Injured Bacteria
Authors: Kang D. H. , Siragusa G. R. 
Published: December 2019

ABSTRACT

A method of recovering sublethally heat-injured bacteria was developed. The procedure (termed the agar underlay method) uses a nonselective agar underlaid with a selective medium. In a two-chambered petri dish, the Lutri plate (LP), a nonselective agar is inoculated with a population of sublethally heat-injured bacteria. After a 2-h repair incubation period, selective agar is added to the bottom chamber of the LP and incubated. By diffusing through the nonselective top agar, selective agents from the underlay medium impart selectivity to the system. By the agar underlay method, recovery rates of the heat-injured food-borne pathogens
Escherichia coli
O157:H7 and
Salmonella typhimurium
were not different (
P
> 0.05) from recovery rates determined with nonselective media. Sublethally heat-injured cells (60°C for 1.5 min in buffer or 80°C for 30 s on meat surfaces) grew and produced a typical colony morphology and color reaction when the agar underlay procedure was used with the appropriate respective selective agars. Unlike agar overlay methods for injury repair, the agar underlay procedure allows the typical selective-medium colony morphology to develop and allows colonies to be more easily picked for further characterization. Higher recovery rates of heat-injured fecal enterococci from bovine fecal samples and total coliforms from animal waste lagoons were obtained by the agar underlay method with selective agars than by direct plating on the respective selective media.
The Presence of Salt and a Curing Agent Reduces Bacteriocin Production by
Lactobacillus sakei
CTC 494, a Potential Starter Culture for Sausage Fermentation
Authors: Leroy Frédéric , de Vuyst Luc 
Published: December 2019

ABSTRACT

The specific conditions in the batter of raw fermented sausages may reduce the efficiency of bacteriocin-producing starter cultures. In this work, using in vitro fermentation, we found that sodium chloride and sodium nitrite interfere with the growth of
Lactobacillus sakei
CTC 494, an organism which produces the antilisterial bacteriocin sakacin K. Because sakacin K production follows primary metabolite kinetics, a decrease in cell formation resulted in a decrease in sakacin K production as well. Sodium chloride dramatically influenced bacteriocin production by decreasing both biomass production and specific bacteriocin production. Sodium nitrite, however, had no effect on specific bacteriocin production and decreased bacteriocin production only because of its effect on cell growth. Moreover, sodium nitrite enhanced the toxic effect of lactic acid on bacterial growth.
Utilization of Heterologous Siderophores Enhances Levels of Iron Available to
Pseudomonas putida
in the Rhizosphere
Authors: Loper Joyce E. , Henkels Marcella D. 
Published: December 2019

ABSTRACT

Pseudomonas
spp. have the capacity to utilize siderophores produced by diverse species of bacteria and fungi, and the present study was initiated to determine if siderophores produced by rhizosphere microorganisms enhance the levels of iron available to a strain of
Pseudomonas putida
in this natural habitat. We used a previously described transcriptional fusion (
pvd
-
inaZ
) between an iron-regulated promoter (
pvd
) and the ice nucleation reporter gene (
inaZ
) to detect alterations in iron availability to
P. putida
. Ice nucleation activity (INA) expressed from the
pvd
-
inaZ
fusion by
P. putida
N1R or N1R Pvd
−
, a derivative deficient in the production of a pyoverdine siderophore, was inversely related to the concentration of ferric citrate in a culture medium. In culture, INA expressed by N1R Pvd
−
(
pvd
-
inaZ
) was reduced in the presence of the ferric complex of pseudobactin-358, a pyoverdine siderophore produced by
P. putida
WCS358 that can be utilized as a source of iron by N1R Pvd
−
. In the rhizosphere of cucumbers grown in sterilized soil, N1R Pvd
−
(
pvd
-
inaZ
) expressed INA, indicating that iron availability was sufficiently low in that habitat to allow transcription of the iron-regulated
pvd
promoter. Coinoculation with WCS358 or N1R significantly decreased INA expressed by N1R Pvd
−
(
pvd
-
inaZ
) in the rhizosphere, whereas coinoculation with a pyoverdine-deficient mutant of WCS358 did not reduce INA expressed by N1R Pvd
−
(
pvd
-
inaZ
). These results indicate that iron availability to N1R Pvd
−
(
pvd
-
inaZ
) in the rhizosphere was enhanced by the presence of another strain of
P. putida
that produces a pyoverdine that N1R Pvd
−
(
pvd
-
inaZ
) was able to utilize as a source of iron. In culture, strain N1R Pvd
−
also utilized ferric complexes of the siderophores enterobactin and aerobactin as sources of iron. In the rhizosphere of cucumbers grown in sterilized soil, INA expressed by N1R Pvd
−
(
pvd
-
inaZ
) was reduced in the presence of strains of
Enterobacter cloacae
that produced enterobactin, aerobactin, or both siderophores, but INA expressed by N1R Pvd
−
(
pvd
-
inaZ
) was not altered in the presence of a mutant of
E. cloacae
deficient in both enterobactin and aerobactin production. Therefore, the iron status of
P. putida
was altered by siderophores produced by an unrelated bacterium coinhabiting the rhizosphere. Finally, we demonstrated that INA expressed by N1R containing
pvd
-
inaZ
in the rhizosphere differed between plants grown in sterilized versus nonsterilized field soil. The results of this study demonstrate that (i)
P. putida
expresses genes for pyoverdine production and uptake in the rhizosphere, but the level of gene expression is influenced by other bacteria that coexist with
P. putida
in this habitat, and (ii) diverse groups of microorganisms can alter the availability of chemical resources in microbial habitats on root surfaces.
Induction and Transcription Studies of the Dextransucrase Gene in
Leuconostoc mesenteroides
NRRL B-512F
Authors: Quirasco M. , López-Munguía A. , Remaud-Simeon M. , Monsan P. , Farrés A. 
Published: December 2019

ABSTRACT

Dextransucrase production by
Leuconostoc mesenteroides
NRRL B-512F in media containing carbon sources other than sucrose is reported for the first time. Dextransucrases were analyzed by gel electrophoresis and by an in situ activity assay. Their polymers and acceptor reaction products were also compared by
13
C nuclear magnetic resonance and high-performance liquid chromatography techniques, respectively. From these analyses, it was found that, independently of the carbon source,
L. mesenteroides
NRRL B-512F produced dextransucrases of the same size and product specificity. The 5′ ends of dextransucrase mRNAs isolated from cells grown under different culture conditions were identical. Based on this evidence, we conclude that dextransucrases obtained from cells grown on the various carbon sources result from the transcription of the same gene. The control of expression occurs at this level. The low dextransucrase yields from cultures in
d
-glucose or
d
-fructose and the enhancement of dextransucrase gene transcription in the presence of sucrose suggest that an activating phenomenon may be involved in the expression mechanism. Dextransucrase mRNA has a size of approximately 4.8 kb, indicating that the gene is located in a monocistronic operon. The transcription start point was localized 34 bp upstream from the ATG start codon. The −10 and −35 sequences found, TATAAT and TTTACA, were highly homologous to the only glycosyltransferase promoter sequence reported for lactic acid bacteria.
Production of Sulfur Flavors by Ten Strains of
Geotrichum candidum
Authors: Berger Celine , Khan Jeffrey A. , Molimard Pascal , Martin Nathalie , Spinnler Henry E. 
Published: December 2019

ABSTRACT

Ten strains of
Geotrichum candidum
were studied on a liquid cheese model medium for the production of sulfur compounds which contribute to the aroma of cheeses. The volatile components produced by each cultured strain were extracted by dynamic headspace extractions, separated and quantified by gas chromatography (GC), and identified by GC-mass spectrometry. It was shown that four strains of this microorganism produced significant quantities of
S
-methyl thioacetate,
S
-methyl thiopropionate,
S
-methyl thiobutanoate,
S
-methyl thio
iso
butanoate,
S
-methyl thio
iso
valerate, and
S
-methyl thiohexanoate. This is the first example of the production of these compounds by a fungus. In addition, dimethyldisulfide, dimethyltrisulfide, dimethylsulfide, and methanethiol, which are more commonly associated with the development of cheese flavor in bacterial cultures, were also produced by
G. candidum
in various yields, depending on the strain selected. The potential application of these strains in cultured microbial associations to produce modified cheeses with more desirable organoleptic properties is discussed.
Requirement for Phosphoglucose Isomerase of
Xanthomonas campestris
in Pathogenesis of Citrus Canker
Authors: Tung Shu Yun , Kuo Tsong Teh 
Published: December 2019

ABSTRACT

A mutant (XT906) of
Xanthomonas campestris
pv. citri, the causal agent of citrus canker, was induced by insertion of the transposon Tn
5tac
1 and isolated. This mutant did not grow or elicit canker disease in citrus leaves but was still able to induce a hypersensitive response in a nonhost plant (the common bean). The mutant was also unable to grow on minimal medium containing fructose or glycerol as the sole carbon source. A 2.5-kb fragment of wild-type DNA that complemented the mutant phenotype of XT906 was isolated. Sequence analysis revealed that this DNA fragment encoded a protein of 562 amino acids that shows homology to phosphoglucose isomerase (PGI). Enzyme activity assay confirmed that the encoded protein possesses PGI activity. Analysis of the activity of the promoter of the
pgi
gene revealed that it was inhibited by growth in complex medium but induced by culture in plant extract. These results demonstrate that PGI is required for pathogenicity of
X. campestris
pv. citri.
Anastomosis Formation and Nuclear and Protoplasmic Exchange in Arbuscular Mycorrhizal Fungi
Authors: Giovannetti Manuela , Azzolini Dario , Citernesi Anna Silvia 
Published: December 2019

ABSTRACT

We observed anastomosis between hyphae originating from the same spore and from different spores of the same isolate of the arbuscular mycorrhizal fungi
Glomus mosseae
,
Glomus caledonium
, and
Glomus intraradices
. The percentage of contacts leading to anastomosis ranged from 35 to 69% in hyphae from the same germling and from 34 to 90% in hyphae from different germlings. The number of anastomoses ranged from 0.6 to 1.3 per cm (length) of hyphae in mycelia originating from the same spore. No anastomoses were observed between hyphae from the same or different germlings of
Gigaspora rosea
and
Scutellospora castanea
; no interspecific or intergeneric hyphal fusions were observed. We monitored anastomosis formation with time-lapse and video-enhanced light microscopy. We observed complete fusion of hyphal walls and the migration of a mass of particles in both directions within the hyphal bridges. In hyphal bridges of
G. caledonium
, light-opaque particles moved at the speed of 1.8 ± 0.06 μm/s. We observed nuclear migration between hyphae of the same germling and between hyphae belonging to different germlings of the same isolate of three
Glomus
species. Our work suggests that genetic exchange may occur through intermingling of nuclei during anastomosis formation and opens the way to studies of vegetative compatibility in natural populations of arbuscular mycorrhizal fungi.
Growth of Facultatively Heterofermentative Lactobacilli on Starter Cell Suspensions
Authors: Rapposch S. , Eliskases-Lechner F. , Ginzinger W. 
Published: December 2019

ABSTRACT

The growth of facultatively heterofermentative lactobacilli (FHL) on cell suspensions of the homofermentative
Lactobacillus helveticus
was investigated. Osmotic lysis of
L. helveticus
led to a significant increase of ribose. It decreased steadily in parallel with the growth of FHL, strongly suggesting that the bacteria used ribose as a growth substrate.
Hemolytic Activity and Siderophore Production in Different
Aeromonas
Species Isolated from Fish
Authors: Santos Jesús A. , González César J. , Otero Andrés , García-López María-Luisa 
Published: December 2019

ABSTRACT

The hemolytic activity and siderophore production of several strains of motile aeromonads were determined. The hemolytic activity of
Aeromonas caviae
and
Aeromonas eucrenophila
was enhanced after trypsinization of the samples. The enhancement of hemolysis was observed in strains that carried an aerolysin-like gene, detected by a PCR procedure. Siderophore production was demonstrated in all but one strain of
Aeromonas jandaei
. No apparent relationship was observed between the presence of plasmid DNA and hemolysis or siderophore production.
Analysis of
nifH
Gene Pool Complexity in Soil and Litter at a Douglas Fir Forest Site in the Oregon Cascade Mountain Range
Authors: Widmer F. , Shaffer B. T. , Porteous L. A. , Seidler R. J. 
Published: December 2019

ABSTRACT

Nitrogen-fixing microbial populations in a Douglas fir forest on the western slope of the Oregon Cascade Mountain Range were analyzed. The complexity of the
nifH
gene pool (
nifH
is the marker gene which encodes nitrogenase reductase) was assessed by performing nested PCR with bulk DNA extracted from plant litter and soil. The restriction fragment length polymorphisms (RFLPs) of PCR products obtained from litter were reproducibly different than the RFLPs of PCR products obtained from the underlying soil. The characteristic differences were found during the entire sampling period between May and September. RFLP analyses of cloned
nifH
PCR products also revealed characteristic patterns for each sample type. Among 42
nifH
clones obtained from a forest litter library nine different RFLP patterns were found, and among 64
nifH
clones obtained from forest soil libraries 13 different patterns were found. Only two of the patterns were found in both the litter and the soil, indicating that there were major differences between the nitrogen-fixing microbial populations. A sequence analysis of clones representing the 20 distinct patterns revealed that 19 of the patterns had a proteobacterial origin. All of the
nifH
sequences obtained from the Douglas fir forest litter localized in a distinct phylogenetic cluster characterized by the
nifH
sequences of members of the genera
Rhizobium
,
Sinorhizobium
, and
Azospirillum
. The
nifH
sequences obtained from soil were found in two additional clusters, one characterized by sequences of members of the genera
Bradyrhizobium
,
Azorhizobium
,
Herbaspirillum
, and
Thiobacillus
and the other, represented by a single
nifH
clone, located between the gram-positive bacteria and the cyanobacteria. Our results revealed the distinctness of the nitrogen-fixing microbial populations in litter and soil in a Douglas fir forest; the differences may be related to special requirements for degradation and mineralization processes in the plant litter.