bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diversity of
l
-Methionine Catabolism Pathways in Cheese-Ripening Bacteria
Authors: Bonnarme Pascal , Psoni Lefki , Spinnler Henry E. 
Published: July 2002

ABSTRACT

Enzymatic activities that could be involved in methanethiol generation in five cheese-ripening bacteria were assayed, and the major sulfur compounds produced were identified.
l
-Methionine and α-keto-γ-methyl-thio-butyric acid demethiolating activities were detected in whole cells and cell extracts (CFEs) of all the bacteria tested. No
l
-methionine deaminase activity could be detected in any of the ripening bacteria and
l
-methionine aminotransferase was detected in CFEs of
Brevibacterium linens
,
Micrococcus luteus
, and
Corynebacterium glutamicum
. The results suggest that several pathways for
l
-methionine catabolism probably coexist in these ripening bacteria.
Bacterial Toxin-Antitoxin Gene System as Containment Control in Yeast Cells
Authors: Kristoffersen P. , Jensen G. B. , Gerdes K. , Piškur J. 
Published: July 2002

ABSTRACTThe potential of a bacterial toxin-antitoxin gene system for use in containment control in eukaryotes was explored. TheEscherichia coli relEandrelBgenes were expressed in the yeastSaccharomyces cerevisiae. Expression of therelEgene was highly toxic to yeast cells. However, expression of therelBgene counteracted the effect ofrelEto some extent, suggesting that toxin-antitoxin interaction also occurs inS. cerevisiae. Thus, bacterial toxin-antitoxin gene systems also have potential applications in the control of cell proliferation in eukaryotic cells, especially in those industrial fermentation processes in which the escape of genetically modified cells would be considered highly risky.
Effect of Flagella on Initial Attachment of
Listeria monocytogenes
to Stainless Steel
Authors: Vatanyoopaisarn Savitri , Nazli Aisha , Dodd Christine E. R. , Rees Catherine E. D. , Waites Will M. 
Published: July 2002

ABSTRACT

At 22°C a flagellin mutant of
Listeria monocytogenes
was found to attach to stainless steel at levels 10-fold lower than wild-type cells, even under conditions preventing active motility. At 37°C, when flagella are not produced, attachment of both strains was identical. Therefore, flagella per se facilitate the early stage of attachment.
Properties of Engineered Poly-3-Hydroxyalkanoates Produced in Recombinant
Escherichia coli
Strains
Authors: Ren Qun , Sierro Nicolas , Kellerhals Michele , Kessler Birgit , Witholt Bernard 
Published: July 2002

ABSTRACT

To prepare medium-chain-length poly-3-hydroxyalkanoates (PHAs) with altered physical properties, we generated recombinant
Escherichia coli
strains that synthesized PHAs with altered monomer compositions. Experiments with different substrates (fatty acids with different chain lengths) or different
E. coli
hosts failed to produce PHAs with altered physical properties. Therefore, we engineered a new potential PHA synthetic pathway, in which ketoacyl-coenzyme A (CoA) intermediates derived from the β-oxidation cycle are accumulated and led to the PHA polymerase precursor
R
-3-hydroxyalkanoates in
E. coli
hosts. By introducing the poly-3-hydroxybutyrate acetoacetyl-CoA reductase (PhbB) from
Ralstonia eutropha
and blocking the ketoacyl-CoA degradation step of the β-oxidation, the ketoacyl-CoA intermediate was accumulated and reduced to the PHA precursor. Introduction of the
phbB
gene not only caused significant changes in the monomer composition but also caused changes of the physical properties of the PHA, such as increase of polymer size and loss of the melting point. The present study demonstrates that pathway engineering can be a useful approach for producing PHAs with engineered physical properties.
Bacillus thuringiensis
Delta-Endotoxin Cry1C Domain III Can Function as a Specificity Determinant for
Spodoptera exigua
in Different, but Not All, Cry1-Cry1C Hybrids
Authors: de Maagd Ruud A. , Weemen-Hendriks Mieke , Stiekema Willem , Bosch Dirk 
Published: July 2002

ABSTRACT

In order to test our hypothesis that
Bacillus thuringiensis
delta-endotoxin Cry1Ca domain III functions as a determinant of specificity for
Spodoptera exigua
, regardless of the origins of domains I and II, we have constructed by cloning and in vivo recombination a collection of hybrid proteins containing domains I and II of various Cry1 toxins combined with domain III of Cry1Ca. Cry1Ab, Cry1Ac, Cry1Ba, Cry1Ea, and Cry1Fa all become more active against
S. exigua
when their domain III is replaced by (part of) that of Cry1Ca. This result shows that domain III of Cry1Ca is an important and versatile determinant of
S. exigua
specificity. The toxicity of the hybrids varied by a factor of 40, indicating that domain I and/or II modulate the activity as well. Cry1Da-Cry1Ca hybrids were an exception in that they were not significantly active against
S. exigua
or
Manduca sexta
, whereas both parental proteins were highly toxic. Incidentally, in a Cry1Ba-Cry1Ca hybrid, Cry1Ca domain III can also strongly increase toxicity for
M. sexta
.
Cloning, Sequencing, and Expression in
Escherichia coli
of the New Gene Encoding β-1,3-Xylanase from a Marine Bacterium,
Vibrio
sp. Strain XY-214
Authors: Araki Toshiyoshi , Hashikawa Shinnosuke , Morishita Tatsuo 
Published: July 2002

ABSTRACT

The
Vibrio
sp. strain XY-214 β-1,3-xylanase gene cloned in
Escherichia coli
DH5α consisted of an open reading frame of 1,383 nucleotides encoding a protein of 460 amino acids with a molecular mass of 51,323 Da and had a signal peptide of 22 amino acids. The transformant enzyme hydrolyzed β-1,3-xylan to produce several xylooligosaccharides.
Cell Wall Chemical Composition of
Enterococcus faecalis
in the Viable but Nonculturable State
Authors: Signoretto Caterina , del Mar Lleò Maria , Tafi Maria Carla , Canepari Pietro 
Published: July 2002

ABSTRACT

The viable but nonculturable (VBNC) state is a survival mechanism adopted by many bacteria (including those of medical interest) when exposed to adverse environmental conditions. In this state bacteria lose the ability to grow in bacteriological media but maintain viability and pathogenicity and sometimes are able to revert to regular division upon restoration of normal growth conditions. The aim of this work was to analyze the biochemical composition of the cell wall of
Enterococcus faecalis
in the VBNC state in comparison with exponentially growing and stationary cells. VBNC enterococcal cells appeared as slightly elongated and were endowed with a wall more resistant to mechanical disruption than dividing cells. Analysis of the peptidoglycan chemical composition showed an increase in total cross-linking, which rose from 39% in growing cells to 48% in VBNC cells. This increase was detected in oligomers of a higher order than dimers, such as trimers (24% increase), tetramers (37% increase), pentamers (65% increase), and higher oligomers (95% increase). Changes were also observed in penicillin binding proteins (PBPs), the enzymes involved in the terminal stages of peptidoglycan assembly, with PBPs 5 and 1 being prevalent, and in autolytic enzymes, with a threefold increase in the activity of latent muramidase-1 in
E. faecalis
in the VBNC state. Accessory wall polymers such as teichoic acid and lipoteichoic acid proved unchanged and doubled in quantity, respectively, in VBNC cells in comparison to dividing cells. It is suggested that all these changes in the cell wall of VBNC enterococci are specific to this particular physiological state. This may provide indirect confirmation of the viability of these cells.
Physiological Responses to Starvation in the Marine Oligotrophic Ultramicrobacterium
Sphingomonas
sp. Strain RB2256
Authors: Fegatella Fitri , Cavicchioli Ricardo 
Published: July 2002

ABSTRACT

Sphingomonas
sp. strain RB2256 is representative of the ultramicrobacteria that proliferate in oligotrophic marine waters. While this class of bacteria is well adapted for growth with low concentrations of nutrients, their ability to respond to complete nutrient deprivation has not previously been investigated. In this study, we examined two-dimensional protein profiles for logarithmic and stationary-phase cells and found that protein spot intensity was regulated by up to 70-fold. A total of 72 and 177 spots showed increased or decreased intensity, respectively, by at least twofold during starvation. The large number of protein spots (1,500) relative to the small genome size (ca. 1.5 Mb) indicates that gene expression may involve co- and posttranslational modifications of proteins. Rates of protein and RNA synthesis were examined throughout the growth phase and up to 7 days of starvation and revealed that synthesis was highly regulated. Rates of protein synthesis and cellular protein content were compared to ribosome content, demonstrating that ribosome synthesis was not directly linked to protein synthesis and that the function of ribosomes may not be limited to translation. By comparing the genetic capacity and physiological responses to starvation of RB2256 to those of the copiotrophic marine bacterium
Vibrio angustum
S14 (J. Ostling, L. Holmquist, and S. Kjelleberg, J. Bacteriol. 178:4901–4908, 1996), the characteristics of a distinct starvation response were defined for
Sphingomonas
strain RB2256. The capacity of this ultramicrobacterium to respond to starvation is discussed in terms of the ecological relevance of complete nutrient deprivation in an oligotrophic marine environment. These studies provide the first evidence that marine oligotrophic ultramicrobacteria may be expected to include a starvation response and the capacity for a high degree of gene regulation.
PhaG-Mediated Synthesis of Poly(3-Hydroxyalkanoates) Consisting of Medium-Chain-Length Constituents from Nonrelated Carbon Sources in Recombinant
Pseudomonas fragi
Authors: Fiedler Silke , Steinbüchel Alexander , Rehm Bernd H. A. 
Published: July 2002

ABSTRACT

Recently, a new metabolic link between fatty acid de novo biosynthesis and biosynthesis of poly(3-hydroxy-alkanoate) consisting of medium-chain-length constituents (C
6
to C
14
) (PHA
MCL
), catalyzed by the 3-hydroxydecanoyl-[acyl-carrier-protein]:CoA transacylase (PhaG), has been identified in
Pseudomonas putida
(B. H. A. Rehm, N. Krüger, and A. Steinbüchel, J. Biol. Chem. 273:24044–24051, 1998). To establish this PHA-biosynthetic pathway in a non-PHA-accumulating bacterium, we functionally coexpressed
phaC1
(encoding PHA synthase 1) from
Pseudomonas aeruginosa
and
phaG
(encoding the transacylase) from
P. putida
in
Pseudomonas fragi
. The recombinant strains of
P. fragi
were cultivated on gluconate as the sole carbon source, and PHA accumulation to about 14% of the total cellular dry weight was achieved. The respective polyester was isolated, and GPC analysis revealed a weight average molar mass of about 130,000 g mol
−1
and a polydispersity of 2.2. The PHA was composed mainly (60 mol%) of 3-hydroxydecanoate. These data strongly suggested that functional expression of
phaC1
and
phaG
established a new pathway for PHA
MCL
biosynthesis from nonrelated carbon sources in
P. fragi
. When fatty acids were used as the carbon source, no PHA accumulation was observed in PHA synthase-expressing
P. fragi
, whereas application of the β-oxidation inhibitor acrylic acid mediated PHA
MCL
accumulation. The substrate for the PHA synthase PhaC1 is therefore presumably directly provided through the enzymatic activity of the transacylase PhaG by the conversion of (
R
)-3-hydroxydecanoyl-ACP to (
R
)-3-hydroxydecanoyl-CoA when the organism is cultivated on gluconate. Here we demonstrate for the first time the establishment of PHA
MCL
synthesis from nonrelated carbon sources in a non-PHA-accumulating bacterium, employing fatty acid de novo biosynthesis and the enzymes PhaG (a transacylase) and PhaC1 (a PHA synthase).
Anaerobic Naphthalene Degradation by a Sulfate-Reducing Enrichment Culture
Authors: Meckenstock Rainer U. , Annweiler Eva , Michaelis Walter , Richnow Hans H. , Schink Bernhard 
Published: July 2002

ABSTRACT

Anaerobic naphthalene degradation by a sulfate-reducing enrichment culture was studied by substrate utilization tests and identification of metabolites by gas chromatography-mass spectrometry. In substrate utilization tests, the culture was able to oxidize naphthalene, 2-methylnaphthalene, 1- and 2-naphthoic acids, phenylacetic acid, benzoic acid, cyclohexanecarboxylic acid, and cyclohex-1-ene-carboxylic acid with sulfate as the electron acceptor. Neither hydroxylated 1- or 2-naphthoic acid derivatives and 1- or 2-naphthol nor the monoaromatic compounds
ortho
-phthalic acid, 2-carboxy-1-phenylacetic acid, and salicylic acid were utilized by the culture within 100 days. 2-Naphthoic acid accumulated in all naphthalene-grown cultures. Reduced 2-naphthoic acid derivatives could be identified by comparison of mass spectra and coelution with commercial reference compounds such as 1,2,3,4-tetrahydro-2-naphthoic acid and chemically synthesized decahydro-2-naphthoic acid. 5,6,7,8-Tetrahydro-2-naphthoic acid and octahydro-2-naphthoic acid were tentatively identified by their mass spectra. The metabolites identified suggest a stepwise reduction of the aromatic ring system before ring cleavage. In degradation experiments with [1-
13
C]naphthalene or deuterated D
8
-naphthalene, all metabolites mentioned derived from the introduced labeled naphthalene. When a [
13
C]bicarbonate-buffered growth medium was used in conjunction with unlabeled naphthalene,
13
C incorporation into the carboxylic group of 2-naphthoic acid was shown, indicating that activation of naphthalene by carboxylation was the initial degradation step. No ring fission products were identified.
Influence of Chlorine Substituents on Rates of Oxidation of Chlorinated Biphenyls by the Biphenyl Dioxygenase of
Burkholderia
sp. Strain LB400
Authors: Arnett Clint M. , Parales Juan V. , Haddock John D. 
Published: July 2002

ABSTRACT

Biphenyl dioxygenase from
Burkholderia
(
Pseudomonas
) sp. strain LB400 catalyzes the first reaction of a pathway for the degradation of biphenyl and a broad range of chlorinated biphenyls (CBs). The effect of chlorine substituents on catalysis was determined by measuring the specific activity of the enzyme with biphenyl and 18 congeners. The catalytic oxygenase component was purified and incubated with individual CBs in the presence of electron transport proteins and cofactors that were required for enzyme activity. The rate of depletion of biphenyl from the assay mixture and the rate of formation of
cis
-biphenyl 2,3-dihydrodiol, the oxidation product, were almost equal, indicating that the assay accurately measured enzyme-specific activity. Four classes of CBs were defined based on their oxidation rates. Class I contained 3-CB and 2,5-CB, which gave rates that were approximately twice that of biphenyl. Class II contained 2,5,3′,4′-CB, 2,3,2′,5′-CB, 2,3,4,5-CB, 2,3,2′,3′-CB, 2,4,5,2′,5′-CB, 2,5,3′-CB, 2,5,4′-CB, 2-CB, and 3,4,5-CB, which gave rates that ranged from 97 to 35% of the biphenyl rate. Class III contained only 2,3,4,2′,5′-CB, which gave a rate that was 4% of the biphenyl rate. Class IV contained 2,4,4′-CB, 2,4,2′,4′-CB, 3,4,5,2′-CB, 3,4,5,3′-CB, 3,5,3′,5′-CB, and 3,4,5,2′,5′-CB, which showed no detectable depletion. Rates were not significantly correlated with the aqueous solubilities of the CBs or the number of chlorine substituents on the rings. Oxidation products were detected for all class I, II, and III congeners and were identified as chlorinated
cis
-dihydrodiols for classes I and II. The specificity of biphenyl dioxygenase for the CBs examined in this study was determined by the relative positions of the chlorine substituents on the aromatic rings rather than the number of chlorine substituents on the rings.
Human Adenoviruses and Coliphages in Urban Runoff-Impacted Coastal Waters of Southern California
Authors: Jiang Sunny , Noble Rachel , Chu Weiping 
Published: July 2002

ABSTRACT

A nested-PCR method was used to detect the occurrence of human adenovirus in coastal waters of Southern California. Twenty- to forty-liter water samples were collected from 12 beach locations from Malibu to the border of Mexico between February and March 1999. All sampling sites were located at mouths of major rivers and creeks. Two ultrafiltration concentration methods, tangential flow filtration (TFF) and vortex flow filtration (VFF), were compared using six environmental samples. Human adenoviruses were detected in 4 of the 12 samples tested after nucleic acid extraction of VFF concentrates. The most probable number of adenoviral genomes ranged from 880 to 7,500 per liter of water. Coliphages were detected at all sites, with the concentration varying from 5.3 to 3332 PFU/liter of water. F-specific coliphages were found at 5 of the 12 sites, with the concentration ranging from 5.5 to 300 PFU/liter. The presence of human adenovirus was not significantly correlated with the concentration of coliphage (
r
= 0.32) but was significantly correlated (
r
= 0.99) with F-specific coliphage. The bacterial indicators (total coliforms, fecal coliforms, and enterococci) were found to exceed California recreational water quality daily limits at 5 of the 12 sites. However, this excess of bacterial indicators did not correlate with the presence of human adenoviruses in coastal waters. The results of this study call for both a reevaluation of our current recreational water quality standards to reflect the viral quality of recreational waters and monitoring of recreational waters for human viruses on a regular basis.
Incidence of Male-KillingRickettsiaspp. (α-Proteobacteria) in the Ten-Spot Ladybird BeetleAdalia decempunctataL. (Coleoptera: Coccinellidae)
Authors: von der Schulenburg J. Hinrich Graf , Habig Michael , Sloggett John J. , Webberley K. Mary , Bertrand Dominique , Hurst Gregory D. D. , Majerus Michael E. N. 
Published: July 2002

ABSTRACTThe diversity of endosymbiotic bacteria that kill male host offspring during embryogenesis and their frequencies in certain groups of host taxa suggest that the evolution of male killing and the subsequent spread of male-killing symbionts are primarily determined by host life history characteristics. We studied the 10-spot ladybird beetle,Adalia decempunctataL. (Coleoptera: Coccinellidae), in which male killing has not been recorded previously, to test this hypothesis, and we also assessed the evolution of the male killer identified by DNA sequence analysis. Our results show thatA. decempunctataharbors male-killingRickettsia(α-proteobacteria). Male-killing bacteria belonging to the genusRickettsiahave previously been reported only for the congeneric two-spot ladybird beetle,Adalia bipunctataL. Phylogenetic analysis ofRickettsiaDNA sequences isolated from different populations of the two host species revealed a single origin of male killing in the genusRickettsia. The data also indicated possible horizontal transfer of symbionts between host species. In addition,A. bipunctatais known to bear at least four different male-killing symbionts in its geographic range two of which coexist in the two locations from whichA. decempunctataspecimens were obtained for the present study. Since only a single male-killing taxon was found inA. decempunctata, we assume that the two closely related ladybird beetle species must differ in the number and/or geographic distribution of male killers. We discuss the importance of these findings to our understanding of the evolution and dynamics of symbiotic associations between male-killing bacteria and their insect hosts.
Microvariation Artifacts Introduced by PCR and Cloning of Closely Related 16S rRNA Gene Sequences
Authors: Speksnijder Arjen G. C. L. , Kowalchuk George A. , De Jong Sander , Kline Elizabeth , Stephen John R. , Laanbroek Hendrikus J. 
Published: July 2002

ABSTRACT
A defined template mixture of seven closely related 16S-rDNA clones was used in a PCR-cloning experiment to assess and track sources of artifactual sequence variation in 16S rDNA clone libraries. At least 14% of the recovered clones contained aberrations. Artifact sources were polymerase errors, a mutational hot spot, and cloning of heteroduplexes and chimeras. These data may partially explain the high degree of microheterogeneity typical of sequence clusters detected in environmental clone libraries.
Survival of Salmonellae on and in Tomato Plants from the Time of Inoculation at Flowering and Early Stages of Fruit Development through Fruit Ripening
Authors: Guo Xuan , Chen Jinru , Brackett Robert E. , Beuchat Larry R. 
Published: July 2002

ABSTRACT

The fate of salmonellae applied to tomato plants was investigated. Five
Salmonella
serotypes were used to inoculate tomato plants before and after fruits set, either by injecting stems with inoculum or brushing flowers with it. Ripe tomato fruits were subjected to microbiological analysis. Peptone wash water, homogenates of stem scar tissues, and homogenates of fruit pulp were serially diluted and plated on bismuth sulfite agar before and after enrichment. Presumptive
Salmonella
colonies were confirmed by serological tests, PCR assay using HILA2 primers, and enterobacterial repetitive intergenic consensus PCR. Of 30 tomatoes harvested from inoculated plants, 11 (37%) were positive for
Salmonella
. Of the
Salmonella
-positive tomatoes, 43 and 40%, respectively, were from plants receiving stem inoculation before and after flower set. Two of eight tomatoes produced from inoculated flowers contained
Salmonella
. Higher percentages of surface (82%) and stem scar tissue (73%) samples, compared to pulp of
Salmonella
-positive tomatoes (55%), harbored the pathogen. Of the five serotypes in the inoculum, Montevideo was the most persistent, being isolated from tomatoes 49 days after inoculation, and Poona was the most dominant, being present in 5 of 11
Salmonella-
positive tomatoes. Results suggest that
Salmonella
cells survive in or on tomato fruits from the time of inoculation at flowering through fruit ripening. Tomato stems and flowers are possible sites at which
Salmonella
may attach and remain viable during fruit development, thus serving as routes or reservoirs for contaminating ripened fruit.
Streptococcus suis
Serotypes Characterized by Analysis of Chaperonin 60 Gene Sequences
Authors: Brousseau Ronald , Hill Janet E. , Préfontaine Gabrielle , Goh Swee-Han , Harel Josée , Hemmingsen Sean M. 
Published: July 2002

ABSTRACT

Streptococcus suis
is an important pathogen of swine which occasionally infects humans as well. There are 35 serotypes known for this organism, and it would be desirable to develop rapid methods methods to identify and differentiate the strains of this species. To that effect, partial chaperonin 60 gene sequences were determined for the 35 serotype reference strains of
S. suis
. Analysis of a pairwise distance matrix showed that the distances ranged from 0 to 0.275 when values were calculated by the maximum-likelihood method. For five of the strains the distances from serotype 1 were greater than 0.1, and for two of these strains the distances were were more than 0.25, suggesting that they belong to a different species. Most of the nucleotide differences were silent; alignment of protein sequences showed that there were only 11 distinct sequences for the 35 strains under study. The chaperonin 60 gene phylogenetic tree was similar to the previously published tree based on 16S rRNA sequences, and it was also observed that strains with identical chaperonin 60 gene sequences tended to have identical 16S rRNA sequences. The chaperonin 60 gene sequences provided a higher level of discrimination between serotypes than the 16S RNA sequences provided and could form the basis for a diagnostic protocol.