bluuebunny/crossref_metadata_2025_split huggingface dataset:
Strain Variation in
Mycobacterium
marinum
Fish Isolates
Authors: Ucko M. , Colorni A. , Kvitt H. , Diamant A. , Zlotkin A. , Knibb W. R. 
Published: April 2009

ABSTRACT

A molecular characterization of two
Mycobacterium
marinum
genes, 16S rRNA and
hsp65
, was carried out with a total of 21 isolates from various species of fish from both marine and freshwater environments of Israel, Europe, and the Far East. The nucleotide sequences of both genes revealed that all
M
.
marinum
isolates from fish in Israel belonged to two different strains, one infecting marine (cultured and wild) fish and the other infecting freshwater (cultured) fish. A restriction enzyme map based on the nucleotide sequences of both genes confirmed the divergence of the Israeli marine isolates from the freshwater isolates and differentiated the Israeli isolates from the foreign isolates, with the exception of one of three Greek isolates from marine fish which was identical to the Israeli marine isolates. The second isolate from Greece exhibited a single base alteration in the 16S rRNA sequence, whereas the third isolate was most likely a new
Mycobacterium
species. Isolates from Denmark and Thailand shared high sequence homology to complete identity with reference strain ATCC 927. Combined analysis of the two gene sequences increased the detection of intraspecific variations and was thus of importance in studying the taxonomy and epidemiology of this aquatic pathogen. Whether the Israeli
M
.
marinum
strain infecting marine fish is endemic to the Red Sea and found extremely susceptible hosts in the exotic species imported for aquaculture or rather was accidentally introduced with occasional imports of fingerlings from the Mediterranean Sea could not be determined.
Occurrence of Mycobacteria in Water Treatment Lines and in Water Distribution Systems
Authors: Le Dantec Corinne , Duguet Jean-Pierre , Montiel Antoine , Dumoutier Nadine , Dubrou Sylvie , Vincent Véronique 
Published: April 2009

ABSTRACT

The frequency of recovery of atypical mycobacteria was estimated in two treatment plants providing drinking water to Paris, France, at some intermediate stages of treatment. The two plants use two different filtration processes, rapid and slow sand filtration. Our results suggest that slow sand filtration is more efficient for removing mycobacteria than rapid sand filtration. In addition, our results show that mycobacteria can colonize and grow on granular activated carbon and are able to enter distribution systems. We also investigated the frequency of recovery of mycobacteria in the water distribution system of Paris (outside buildings). The mycobacterial species isolated from the Paris drinking water distribution system are different from those isolated from the water leaving the treatment plants. Saprophytic mycobacteria (present in 41.3% of positive samples), potentially pathogenic mycobacteria (16.3%), and unidentifiable mycobacteria (54.8%) were isolated from 12 sites within the Paris water distribution system.
Mycobacterium gordonae
was preferentially recovered from treated surface water, whereas
Mycobacterium nonchromogenicum
was preferentially recovered from groundwater. No significant correlations were found among the presence of mycobacteria, the origin of water, and water temperature.
Molecular Analysis of Maltotriose Transport and Utilization bySaccharomycescerevisiae
Authors: Day Rachel E. , Rogers Peter J. , Dawes Ian W. , Higgins Vincent J. 
Published: April 2009

ABSTRACTEfficient fermentation of maltotriose is a desired property ofSaccharomycescerevisiaefor brewing. In a standard wort, maltotriose is the second most abundant sugar, and slower uptake leads to residual maltotriose in the finished product. The limiting factor of sugar metabolism is its transport, and there are conflicting reports on whether a specific maltotriose permease exists or whether the mechanisms responsible for maltose uptake also carry out maltotriose transport. In this study, radiolabeled maltotriose was used to show that overexpression of the maltose permease gene,MAL61, in an industrial yeast strain resulted in an increase in the rate of transport of maltotriose as well as maltose. A strain derived from W303-1A and lacking any maltose or maltotriose transporter but carrying a functional maltose transport activator (MAL63) was developed. By complementing this strain with permeases encoded byMAL31,MAL61, andAGT1, it was possible to measure their specific transport kinetics by using maltotriose and maltose. All three permeases were capable of high-affinity transport of maltotriose and of allowing growth of the strain on the sugar. Maltotriose utilization from the permease encoded byAGT1was regulated by the same genetic mechanisms as those involving the maltose transcriptional activator. Competition studies carried out with two industrial strains, one not containing any homologue ofAGT1, showed that maltose uptake and maltotriose uptake were competitive and that maltose was the preferred substrate. These results indicate that the presence of residual maltotriose in beer is not due to a genetic or physiological inability of yeast cells to utilize the sugar but rather to the lower affinity for maltotriose uptake in conjunction with deteriorating conditions present at the later stages of fermentation. Here we identify molecular mechanisms regulating the uptake of maltotriose and determine the role of each of the transporter genes in the cells.
Biodegradation of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine and Its Mononitroso Derivative Hexahydro-1-Nitroso-3,5-Dinitro-1,3,5-Triazine by
Klebsiella pneumoniae
Strain SCZ-1 Isolated from an Anaerobic Sludge
Authors: Zhao Jian-Shen , Halasz Annamaria , Paquet Louise , Beaulieu Chantale , Hawari Jalal 
Published: April 2009

ABSTRACT

In previous work, we found that an anaerobic sludge efficiently degraded hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), but the role of isolates in the degradation process was unknown. Recently, we isolated a facultatively anaerobic bacterium, identified as
Klebsiella pneumoniae
strain SCZ-1, using MIDI and the 16S rRNA method from this sludge and employed it to degrade RDX. Strain SCZ-1 degraded RDX to formaldehyde (HCHO), methanol (CH
3
OH) (12% of total C), carbon dioxide (CO
2
) (72% of total C), and nitrous oxide (N
2
O) (60% of total N) through intermediary formation of methylenedinitramine (O
2
NNHCH
2
NHNO
2
). Likewise, hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) was degraded to HCHO, CH
3
OH, and N
2
O (16.5%) with a removal rate (0.39 μmol · h
−1
· g [dry weight] of cells
−1
) similar to that of RDX (0.41 μmol · h
−1
· g [dry weight] of cells
−1
) (biomass, 0.91 g [dry weight] of cells · liter
−1
). These findings suggested the possible involvement of a common initial reaction, possibly denitration, followed by ring cleavage and decomposition in water. The trace amounts of MNX detected during RDX degradation and the trace amounts of hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine detected during MNX degradation suggested that another minor degradation pathway was also present that reduced —NO
2
groups to the corresponding —NO groups.
RNA Stable Isotope Probing, a Novel Means of Linking Microbial Community Function to Phylogeny
Authors: Manefield Mike , Whiteley Andrew S. , Griffiths Robert I. , Bailey Mark J. 
Published: April 2009

ABSTRACT

Identifying microorganisms responsible for recognized environmental processes remains a great challenge in contemporary microbial ecology. Only in the last few years have methodological innovations provided access to the relationship between the function of a microbial community and the phylogeny of the organisms accountable for it. In this study stable-isotope-labeled [
13
C]phenol was fed into a phenol-degrading community from an aerobic industrial bioreactor, and the
13
C-labeled RNA produced was used to identify the bacteria responsible for the process. Stable-isotope-labeled RNA was analyzed by equilibrium density centrifugation in concert with reverse transcription-PCR and denaturing gradient gel electrophoresis. In contradiction with findings from conventional methodologies, this unique approach revealed that phenol degradation in the microbial community under investigation is dominated by a member of the
Thauera
genus. Our results suggest that this organism is important for the function of this bioreactor.
Membrane-Bound ATPase Contributes to Hop Resistance ofLactobacillus brevis
Authors: Sakamoto Kanta , van Veen H. W. , Saito Hiromi , Kobayashi Hiroshi , Konings Wil N. 
Published: April 2009

ABSTRACTThe activity of the membrane-bound H+-ATPase of the beer spoilage bacteriumLactobacillus brevisABBC45 increased upon adaptation to bacteriostatic hop compounds. The ATPase activity was optimal around pH 5.6 and increased up to fourfold whenL. breviswas exposed to 666 μM hop compounds. The extent of activation depended on the concentration of hop compounds and was maximal at the highest concentration tested. The ATPase activity was strongly inhibited byN,N′-dicyclohexylcarbodiimide, a known inhibitor of FoF1-ATPase. Western blots of membrane proteins ofL. breviswith antisera raised against the α- and β-subunits of FoF1-ATPase fromEnterococcus hiraeshowed that there was increased expression of the ATPase after hop adaptation. The expression levels, as well as the ATPase activity, decreased to the initial nonadapted levels when the hop-adapted cells were cultured further without hop compounds. These observations strongly indicate that proton pumping by the membrane-bound ATPase contributes considerably to the resistance ofL. brevisto hop compounds.
Efficacy of UV Irradiation in Inactivating
Cryptosporidium
parvum
Oocysts
Authors: Morita Shigemitsu , Namikoshi Atsushi , Hirata Tsuyoshi , Oguma Kumiko , Katayama Hiroyuki , Ohgaki Shinichiro , Motoyama Nobuyuki , Fujiwara Masahiro 
Published: April 2009

ABSTRACT

To evaluate the effectiveness of UV irradiation in inactivating
Cryptosporidium parvum
oocysts, the animal infectivities and excystation abilities of oocysts that had been exposed to various UV doses were determined. Infectivity decreased exponentially as the UV dose increased, and the required dose for a 2-log
10
reduction in infectivity (99% inactivation) was approximately 1.0 mWs/cm
2
at 20°C. However,
C. parvum
oocysts exhibited high resistance to UV irradiation, requiring an extremely high dose of 230 mWs/cm
2
for a 2-log
10
reduction in excystation, which was used to assess viability. Moreover, the excystation ability exhibited only slight decreases at UV doses below 100 mWs/cm
2
. Thus, UV treatment resulted in oocysts that were able to excyst but not infect. The effects of temperature and UV intensity on the UV dose requirement were also studied. The results showed that for every 10°C reduction in water temperature, the increase in the UV irradiation dose required for a 2-log
10
reduction in infectivity was only 7%, and for every 10-fold increase in intensity, the dose increase was only 8%. In addition, the potential of oocysts to recover infectivity and to repair UV-induced injury (pyrimidine dimers) in DNA by photoreactivation and dark repair was investigated. There was no recovery in infectivity following treatment by fluorescent-light irradiation or storage in darkness. In contrast, UV-induced pyrimidine dimers in the DNA were apparently repaired by both photoreactivation and dark repair, as determined by endonuclease-sensitive site assay. However, the recovery rate was different in each process. Given these results, the effects of UV irradiation on
C. parvum
oocysts as determined by animal infectivity can conclusively be considered irreversible.
Low-Shear Modeled Microgravity Alters the
Salmonella enterica
Serovar Typhimurium Stress Response in an RpoS-Independent Manner
Authors: Wilson James W. , Ott C. Mark , Ramamurthy Rajee , Porwollik Steffen , McClelland Michael , Pierson Duane L. , Nickerson Cheryl A. 
Published: April 2009

ABSTRACT

We have previously demonstrated that low-shear modeled microgravity (low-shear MMG) serves to enhance the virulence of a bacterial pathogen,
Salmonella enterica
serovar Typhimurium. The
Salmonella
response to low-shear MMG involves a signaling pathway that we have termed the low-shear MMG stimulon, though the identities of the low-shear MMG stimulon genes and regulatory factors are not known. RpoS is the primary sigma factor required for the expression of genes that are induced upon exposure to different environmental-stress signals and is essential for virulence in mice. Since low-shear MMG induces a
Salmonella
acid stress response and enhances
Salmonella
virulence, we reasoned that RpoS would be a likely regulator of the
Salmonella
low-shear MMG response. Our results demonstrate that low-shear MMG provides cross-resistance to several environmental stresses in both wild-type and isogenic
rpoS
mutant strains. Growth under low-shear MMG decreased the generation time of both strains in minimal medium and increased the ability of both strains to survive in J774 macrophages. Using DNA microarray analysis, we found no evidence of induction of the RpoS regulon by low-shear MMG but did find that other genes were altered in expression under these conditions in both the wild-type and
rpoS
mutant strains. Our results indicate that, under the conditions of these studies, RpoS is not required for transmission of the signal that induces the low-shear MMG stimulon. Moreover, our studies also indicate that low-shear MMG can be added to a short list of growth conditions that can serve to preadapt an
rpoS
mutant for resistance to multiple environmental stresses.
Pine Oil Cleaner-Resistant
Staphylococcus aureus
: Reduced Susceptibility to Vancomycin and Oxacillin and Involvement of SigB
Authors: Price Christopher T. D. , Singh Vineet K. , Jayaswal Radheshyam K. , Wilkinson Brian J. , Gustafson John E. 
Published: April 2009

ABSTRACT

Mutants of
Staphylococcus aureus
strain COL resistant to a household pine oil cleaner (POC) were isolated on laboratory media containing POC.
S. aureus
mutants expressing the POC resistance (POC
r
) phenotype also demonstrate reduced susceptibility to the cell wall-active antibiotics vancomycin and oxacillin. The POC
r
phenotype is reliant on the
S. aureus
alternative transcription factor SigB, since inactivation of
sigB
abolished expression of elevated POC resistance and the reductions in vancomycin and oxacillin susceptibilities. The isolation of suppressor mutants of COL
sigB
::
kan
, which maintain the
sigB
::
kan
allele, indicates that the POC
r
phenotype can also be expressed to a lesser degree via a
sigB
-independent mechanism. These results bolster a growing body of reports suggesting that common disinfectants can select for bacteria with reduced susceptibilities to antibiotics. A series of in vitro-selected glycopeptide-intermediate
S. aureus
(GISA) isolates also expressed reductions in POC susceptibility compared to parent strains. Viewed collectively, our evidence suggests that mutations leading to the POC
r
phenotype may also be involved with the mechanism that leads to the GISA phenotype.
Food-Grade Delivery System for Controlled Gene Expression in
Lactococcus lactis
Authors: Henrich B. , Klein J. R. , Weber B. , Delorme C. , Renault P. , Wegmann U. 
Published: April 2009

ABSTRACT

A food-grade system for the delivery of desired genes to
Lactococcus lactis
, their inducible expression, and their transfer to related strains was established. Based on the thermosensitive pG
+
host replicon, two types of plasmid vectors were constructed which contained sections of either the chromosomal
leu
operon of
L. lactis
or the
tel
operon from the lactococcal sex factor. Genes cloned into the
leu
or
tel
sequences of these vectors were delivered to the homologous regions of the chromosome or the sex factor through two single crossovers, leading to integration of the recombinant plasmids and subsequent excision of the vector portions. Inducible transcription of integrated genes was achieved by using the nisin-controlled expression (NICE) system. To establish the signal transduction genes
nisRK
in
L. lactis
, the vectors pLNG1363 (targeted to the chromosome) and pUK500 (targeted to the sex factor) were constructed. Fusions of six different peptidase genes (
pep
) from
Lactobacillus delbrueckii
with the nisin-inducible promoter

P
nisA

were delivered to the sex factor with derivatives of the vector pUK300. Food-grade recombinants of
L. lactis
were constructed which had the
nisRK
genes and individual

P
nisA

::
pep
fusions integrated either separately into the chromosome and the sex factor or simultaneously into the sex factor. With both types of recombinants, expression of

P
nisA

::
pep
fusions after induction with nisin was demonstrated. Depending on the loci used for integration of
nisRK
, variable induction rates were observed. Furthermore, an engineered sex factor carrying a

P
nisA

::
pepI
fusion was transfered by conjugation between two strains of
L. lactis
at a frequency of 4 × 10
−4
.
Inhibition of
Candida albicans
Biofilm Formation by Farnesol, a Quorum-Sensing Molecule
Authors: Ramage Gordon , Saville Stephen P. , Wickes Brian L. , López-Ribot José L. 
Published: April 2009

ABSTRACT

Farnesol is a quorum-sensing molecule that inhibits filamentation in
Candida albicans
. Both filamentation and quorum sensing are deemed to be important factors in
C. albicans
biofilm development. Here we examined the effect of farnesol on
C. albicans
biofilm formation.
C. albicans
adherent cell populations (after 0, 1, 2, and 4 h of adherence) and preformed biofilms (24 h) were treated with various concentrations of farnesol (0, 3, 30, and 300 μM) and incubated at 37°C for 24 h. The extent and characteristics of biofilm formation were then assessed microscopically and with a semiquantitative colorimetric technique based on the use of 2,3-bis(2-methoxy-4-nitro-5-sulfo-phenyl)-2H-tetrazolium-5-carboxanilide. The results indicated that the effect of farnesol was dependent on the concentration of this compound and the initial adherence time, and preincubation with 300 μM farnesol completely inhibited biofilm formation. Supernatant media recovered from mature biofilms inhibited the ability of planktonic
C. albicans
to form filaments, indicating that a morphogenetic autoregulatory compound is produced in situ in biofilms. Northern blot analysis of RNA extracted from cells in biofilms indicated that the levels of expression of
HWP1
, encoding a hypha-specific wall protein, were decreased in farnesol-treated biofilms compared to the levels in controls. Our results indicate that farnesol acts as a naturally occurring quorum-sensing molecule which inhibits biofilm formation, and we discuss its potential for further development and use as a novel therapeutic agent.
Characterization of the
melA
Locus for α-Galactosidase in
Lactobacillus plantarum
Authors: Silvestroni Aurelio , Connes Cristelle , Sesma Fernando , de Giori Graciela Savoy , Piard Jean-Christophe 
Published: April 2009

ABSTRACT

Alpha-galactosides are abundant sugars in legumes such as soy. Because of the lack of α-galactosidase (α-Gal) in the digestive tract, humans are unable to digest these sugars, which consequently induce flatulence. To develop the consumption of the otherwise highly nutritional soy products, the use of exogenous α-Gal is promising. In this framework, we characterized the
melA
gene for α-Gal in
Lactobacillus plantarum
. The
melA
gene encodes a cytoplasmic 84-kDa protein whose enzymatically active form occurs as oligomers. The
melA
gene was cloned and expressed in
Escherichia coli
, yielding an active α-Gal. We show that
melA
is transcribed from its own promoter, yielding a monocistronic mRNA, and that it is regulated at the transcriptional level, i.e., it is induced by melibiose but is not totally repressed by glucose. Posttranscriptional regulation by the carbon source could also occur. Upstream of
melA
, a putative galactoside transporter, designated RafP, was identified that shows high homology to LacS, the unique transporter for both α- and β-galactosides in
Streptococcus thermophilus. rafP
is also expressed as a monocistronic mRNA. Downstream of
melA
, the
lacL
and
lacM
genes were identified that encode a heterodimeric β-galactosidase. A putative
galM
gene identified in the same cluster suggests the presence of a galactose operon. These results indicate that the genes involved in galactoside catabolism are clustered in
L. plantarum
ATCC 8014. This first genetic characterization of
melA
and of its putative associated transporter,
rafP
, in a lactobacillus opens doors to various applications both in the manufacture of soy-derived products and in probiotic and nutraceutical issues.
Identification by PCR of
Fusarium culmorum
Strains Producing Large and Small Amounts of Deoxynivalenol
Authors: Bakan B. , Giraud-Delville C. , Pinson L. , Richard-Molard D. , Fournier E. , Brygoo Y. 
Published: April 2009

ABSTRACT

Thirty deoxynivalenol-producing
F. culmorum
strains, isolated from wheat grains, were incubated in vitro and analyzed for trichothecene production. Seventeen strains produced more than 1 ppm of deoxynivalenol and acetyldeoxynivalenol and were considered high-deoxynivalenol-producing strains, whereas 13
F. culmorum
strains produced less than 0.07 ppm of trichothecenes and were considered low-deoxynivalenol-producing strains. For all strains, a 550-base portion of the trichodiene synthase gene (
tri5
) was amplified and sequenced. According to the
tri5
data, the
F. culmorum
strains tested clustered into two groups that correlated with in vitro deoxynivalenol production. For three high-producing and three low-producing
F. culmorum
strains, the
tri5-tri6
intergenic region was then sequenced, which confirmed the two separate clusters within the
F. culmorum
strains. According to the
tri5-tri6
sequence data, specific PCR primers were designed to allow differentiation of high-producing from low-producing
F. culmorum
strains.
Expression of DuplicatemsaGenes in the Salmonid PathogenRenibacteriumsalmoninarum
Authors: Rhodes Linda D. , Coady Alison M. , Strom Mark S. 
Published: April 2009

ABSTRACTRenibacterium salmoninarumis a gram-positive bacterium responsible for bacterial kidney disease of salmon and trout.R.salmoninarumhas two identical copies of the gene encoding major soluble antigen (MSA), an immunodominant, extracellular protein. To determine whether one or both copies ofmsaare expressed, reporter plasmids encoding a fusion of MSA and green fluorescent protein controlled by 0.6 kb of promoter region frommsa1ormsa2were constructed and introduced intoR.salmoninarum. Single copies of the reporter plasmids integrated into the chromosome by homologous recombination. Expression of mRNA and protein from the integrated plasmids was detected, and transformed cells were fluorescent, demonstrating that bothmsa1andmsa2are expressed under in vitro conditions. This is the first report of successful transformation and homologous recombination inR.salmoninarum.