Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “BACTERIUM”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20Linked to original sources
PubMed1997

Extracellular reduction of selenite by a novel marine photosynthetic bacterium.

A novel purple nonsulfur bacterium strain NKPB030619, which has resistance to over 5 mM selenite, was isolated from a marine environment. An initial concentration of 1.1 mM selenite, added to the medium, was decreased to under 0.05 mM within 5 days. The color of the cell suspension turned red within 2 days. The red coloration gradually decreased and black precipitates appeared during 2 weeks of cultivation. Under these conditions, two main types of deposit were formed extracellularly. These deposits were thought to contain red amorphous selenium and black vitreous selenium. The selenite reduction to elemental selenium in this bacterium was induced by the introduction of light and L-malic acid under anaerobic conditions. These results suggest that selenite reduction is coupled with photosynthesis and L-malic acid can serve as the indirect electron donor for its reduction. Phylogenetic analysis based on the 16S rDNA sequence showed that NKPB0360619 belongs to the alpha subdivision of Proteobacteria and is classified into the Rhodobacter species. The highest similarity of 86.2% was observed with R. sphaeroides.

Bacteria↗
PubMed1998

Identification of tandemly repeated type VI cellulose-binding domains in an endoglucanase from the aerobic soil bacterium Cellvibrio mixtus.

Cellulose-binding domains (CBD) play a pivotal role during plant cell wall hydrolysis by cellulases and xylanases from aerobic soil bacteria. Recently we have reported the molecular characterisation of a single-domain endoglucanase from Cellvibrio mixtus, suggesting that some cellulases produced by this aerobic bacterium preferentially hydrolyse soluble cellulosic substrates. Here we describe the complete nucleotide sequence of a second cellulase gene, celB, from the soil bacterium C. mixtus. It revealed an open reading frame of 1863 bp that encoded a polypeptide, defined as cellulase B (CelB) with a predicted Mr of 66 039. CelB contained a glycosyl hydrolase family 5 catalytic domain at its N terminus followed by two repeated domains, which exhibited sequence identity with type VI CBD previously found in xylanases. Full-length CelB bound to cellulose while catalytically active truncated cellulase derivatives were unable to bind the polysaccharide, confirming that CelB is a modular enzyme and that the type VI CBD homologues were functional. Analysis of the biochemical properties of CelB revealed that the enzyme hydrolyses a range of cellulosic substrates, although it was unable to depolymerise Avicel. We propose that type VI CBD, usually found in xylanases, provide an additional mechanism by which cellulases can accumulate on the surface of the plant cell wall, although they do not potentiate cellulase activity directly. The results demonstrate that C. mixtus, in common with other aerobic bacteria, is able to produce cellulases that are directed to the hydrolysis of cellulose in its natural environment, the plant cell wall.

Amino Acid Sequence↗
PubMed2004

A novel exopolymer-producing bacterium, Paracoccus zeaxanthinifaciens subsp. payriae, isolated from a "kopara" mat located in Rangiroa, an atoll of French Polynesia.

An aerobic, mesophilic and heterotrophic marine bacterium designated RA19, able to produce two different exocellular polymers and zeaxanthin, was isolated from a French polynesian bacterial mat (localy named "kopara") situated in the atoll of Rangiroa. This microorganism, on the basis of its phenotypical features and the genotypic investigations, can be clearly assigned to the Parococcus zeaxanthinifaciens species and the name Parococcus zeaxanthinifaciens subsp. payriae is proposed. Optimal growth occurs between 30 degrees C and 35 degrees C, at pH between 6.5 and 7.5 and at ionic strength between 20 and 40 g/L of NaCl. The guanine-plus-cytosine content of DNA was 65.6%. This bacterium excreted, under laboratory conditions, two different polymers: a water-soluble exopolysaccharide (EPSI) consisting of 5 different sugars and a non-water-soluble macromolecule assumed to be of a glycoproteinic nature. The high sulfate content of the EPS1 and preliminary biological tests clearly showed that applications could be found in the very near future for both polymers in the cosmetic area. Their contribution to the viscous laminated microbial mat locally called "kopara" can be also mentioned.

Base Composition↗
PubMed2005

Polaribacter butkevichii sp. nov., a novel marine mesophilic bacterium of the family Flavobacteriaceae.

A novel heterotrophic, yellow pigmented, aerobic, Gram-negative, nonmotile, oxidase- and catalase-positive bacterium KMM 3,938(T) was isolated from sea water collected in the Sea of Japan, Russia. The strain grew at mesophilic temperature range, and required the presence of NaCl for growth. 16S rRNA gene sequence analysis revealed that strain KMM 3,938(T) is a member of the family Flavobacteriaceae. The predominant fatty acids were C13:0 iso, C14:0 iso, C15:0 iso, C15:0, C15:1Delta6, 3OH-C15:0:3 iso, and 3OH-C15:0. The G + C content of the DNA of KMM 3938(T) was 32.4 mol%. On the basis of phenotypic, chemotaxonomic, genotypic, and phylogenetic characteristics, the novel bacterium was assigned to the genus Polaribacter as Polaribacter butkevichii sp. nov. The type strain is KMM 3938(T )(= KCTC 12100(T) = CCUG 48005(T)).

Aerobiosis↗
PubMed2005

Expression of the Bacillus thuringiensis mosquitocidal toxin Cry11Aa in the aquatic bacterium Asticcacaulis excentricus.

A mosquitocidal aquatic bacterium has been developed by introducing an operon containing the cry11Aa, and p20 genes from Bacillus thuringiensis subsp. israelensis (Bti) into the gram-negative aquatic bacterium Asticcacaulis excentricus. After transformation, the cry11Aa gene was successfully expressed in recombinant A. excentricus under the tac promoter, at the level of 0.04 pg/cell. The recombinant bacteria were toxic to Aedes aegypti larvae with an LC(50) of 6.83 x 10(5) cells/mL. We believe that these bacteria may have potential as genetically engineered microorganisms for the control of mosquito larvae.

Animals↗
PubMed1998

Anaerobic degradation and transformation of p-toluidine by the sulfate-reducing bacterium Desulfobacula toluolica.

The ability of the strictly anaerobic sulfate-reducing bacterium Desulfobacula toluolica (strain Tol2) to cometabolically degrade p-toluidine (p-methylaniline) while using toluene as the primary source of carbon and energy has been studied. This organism has been shown to modify and degrade toluidine in dense cell suspensions when no other source of carbon and energy is added. The metabolism led to the formation of a variety of metabolites. From these metabolites a biphenyl-like compound as well as phenylacetic acid have been identified by means of HPLC/MS techniques. The probable conversion of p-toluidine to p-aminophenylacetic acid and phenylacetic acid as dead end products suggested that this organism initiates p-toluidine degradation by the carboxylation of the methyl group. If this could be validated in further experiments, it would be the first time that a toluidine was carboxylated at the methyl moiety by an anaerobic, sulfate-reducing bacterium.

Bacteria, Anaerobic↗
PubMed2000

Influence of sulfate-reducing bacteria on outdoor hydrogen production by photosynthetic bacterium with seawater.

The application of seawater for bacterial fermentative production is a cost-effective technology. Hydrogen production by marine photosynthetic bacterium with seawater failed to continue after more than 10 days, and was accompanied by the formation of hydrogen sulfide and a change in culture color from red to black. However, substrate consumption in the blackish culture was comparable to that in a hydrogen-producing culture. A decrease in hydrogen production occurred upon the addition of sodium sulfide at concentrations of 1.5 mM or higher. PCR analysis targeted at the 16S rDNA sequence selective for sulfate-reducing bacteria revealed the existence of sulfate-reducing bacteria in inoculation cultures of the phototrophic bacterium and medium for hydrogen production. Hence, the high sulfate concentration of seawater, the low oxidation-reduction potential under hydrogen-producing conditions, and the presence of electron donors such as acetate might promote the metabolic activities of sulfate-reducing bacteria, resulting in the deterioration of hydrogen production with seawater.

Bioreactors↗
PubMed2002

Inoculation of field-established mulberry and papaya with arbuscular mycorrhizal fungi and a mycorrhiza helper bacterium.

The effects of soil inoculation with arbuscular mycorrhizal (AM) fungi and a mycorrhiza helper bacterium (MHB) were investigated on mulberry and papaya plants already established in the field. Ten-year-old mulberry plants (var. M5) were inoculated with Glomus fasciculatum and 1.5-year-old papaya plants (var. Solo) were inoculated with a mixed culture of G. mosseae and G. caledonium with or without Bacillus coagulans at two levels of P fertilizer. Growth, P uptake, yield and AM colonization levels were monitored. Leaf yield in mulberry and fruit yield in papaya were minimal in uninoculated plants given 50% recommended P. However, crop yields of both mulberry and papaya inoculated with AM fungi alone or together with the bacterium and given 50% recommended P were statistically on a par with that of uninoculated plants given 100% recommended P. As inoculation of B. coagulans increased mycorrhiza levels in AM fungal-inoculated plants, this may be included in the class of MHB. Thus, mulberry and papaya already established in the field may respond to AM inoculation and MHB may increase symbiosis development by efficient AM fungi.

Bacillus↗
PubMed2002

Intracellular ion and organic solute concentrations of the extremely halophilic bacterium Salinibacter ruber.

Salinibacter ruber is a red obligatory aerobic chemoorganotrophic extremely halophilic Bacterium, related to the order Cytophagales. It was isolated from saltern crystallizer ponds, and requires at least 150 g l(-1) salt for growth. The cells have an extremely high potassium content, the ratio K(+)/protein being in the same range as in halophilic Archaea of the order Halobacteriales. X-ray microanalysis in the electron microscope of cells grown in medium of 250 g l(-1) salt confirmed the high intracellular K(+)concentrations, and showed intracellular chloride to be about as high as the cation concentrations within the cells. A search for intracellular organic osmotic solutes, using (13)C-NMR and HPLC techniques, showed glutamate, glycine betaine, and N-alpha-acetyllysine to be present in low concentrations only, contributing very little to the overall osmotic balance. The results presented suggest that the extremely halophilic Bacterium Salinibacteruses a similar mode of haloadaptation to that of the Archaea of the order Halobacteriales, and does not accumulate organic osmotic solutes such as are used by all other known halophilic and halotolerant aerobic Bacteria.

Bacteroidetes↗
PubMed2004

Promoters from a cold-adapted bacterium: definition of a consensus motif and molecular characterization of UP regulative elements.

Although low-temperature tolerant micro-organisms were discovered long ago, limited information is still available on the transcription machinery in cold-adapted bacteria. This knowledge represents a necessary background for the investigation of the adaptation of gene-expression mechanisms at low temperatures. The recent development of a shuttle genetic system for the transformation of the cold-adapted Gram-negative bacterium Pseudoalteromonas haloplanktis strain TAC125 has made possible the isolation of the psychrophilic promoters described in this paper. TAC125 genomic DNA fragments were cloned in the shuttle vector and the promoter-containing recombinant clones were selected for their ability to express a promoter-less lacZ gene. The nucleotide sequence of several selected inserts and the transcription start points of the transcribed m-RNAs were determined. A promoter consensus sequence for Pseudoalteromonas haloplanktis TAC125 was proposed on the basis of a sequence comparison between the various active promoters. Furthermore, the identification and the functional characterization of two UP elements from this cold-adapted bacterium are also reported.

Adaptation, Physiological↗
PubMed2004

Gene structure and transcriptional regulation of dnaK and dnaJ genes from a psychrophilic bacterium, Colwellia maris.

The dnaK and dnaJ genes, encoding heat shock proteins, were cloned from a psychrophilic bacterium, Colwellia maris. Significant homology was evident comparing DnaK and DnaJ of the psychrophilile with the counterparts of mesophilic and thermophilic bacteria. In the DnaJ protein, three conserved regions of the Hsp40 family were observed. A putative promoter similar to the sigma32 consensus sequence was found upstream of the dnaK gene. The G+C content in the 5'-untranslated region of the dnaK gene was much lower than that in the corresponding region of mesophilic bacteria. Northern-blot analysis and primer-extension analysis showed that both genes were transcribed separately as monocistronic mRNAs. Following several temperature upshifts from 10 to 26 degrees C, maximum induction of the dnaK and dnaJ mRNAs was detected at 20 degrees C, suggesting that this temperature induces the heat shock response in this bacterium. In addition, the level of the induction of the dnaJ gene was much lower than that of the dnaK gene. These findings together revealed several specific features of the heat shock response at a relatively low temperature in psychrophiles.

Amino Acid Sequence↗
PubMed2004

Thialkalivibrio halophilus sp. nov., a novel obligately chemolithoautotrophic, facultatively alkaliphilic, and extremely salt-tolerant, sulfur-oxidizing bacterium from a hypersaline alkaline lake.

A new chemolithoautotrophic, facultatively alkaliphilic, extremely salt-tolerant, sulfur-oxidizing bacterium was isolated from an alkaline hypersaline lake in the Altai Steppe (Siberia, Russia). According to 16S rDNA analysis and DNA-DNA hybridization, strain HL 17T was identified as a new species of the genus Thialkalivibrio belonging to the gamma subdivision of the Proteobacteria for which the name Thialkalivibrio halophilus is proposed. Strain HL 17T is an extremely salt-tolerant bacterium growing at sodium concentrations between 0.2 and 5 M, with an optimum of 2 M Na+. It grew at high concentrations of NaCl and of Na2CO3/NaHCO3 (soda). Strain HL 17T is a facultative alkaliphile growing at pH range 7.5-9.8, with a broad optimum between pH 8.0 and 9.0. It used reduced inorganic sulfur compounds (thiosulfate, sulfide, polysulfide, elemental sulfur, and tetrathionate) as energy sources and electron donors. In continuous culture under energy limitation, thiosulfate was stoichiometrically oxidized to sulfate. In sodium carbonate medium under alkaline conditions, the maximum growth rate was similar, while the biomass yield was lower as compared with the NaCl-grown culture. The maximum sulfur-oxidizing capacity measured in washed cells was higher in the soda buffer independent of the growth conditions. The compatible solute content of the biomass was higher in the sodium chloride-grown culture than in the sodium carbonate/bicarbonate-grown culture. The data suggest that the osmotic pressure differences between soda and NaCl solutions might be responsible for the difference observed in compatible solutes production. This may have important implications in overall energetic metabolism of high salt adaptation.

Chromatiaceae↗
PubMed2005

Novel psychrophilic anaerobic spore-forming bacterium from the overcooled water brine in permafrost: description Clostridium algoriphilum sp. nov.

A gram-positive, motile, strict anaerobic spore-forming bacterium was isolated from the over-cooled brine in the permafrost. The optimal temperature for isolate growth was 5-6 degrees C at pH 6.8-7.2. The bacterium was growing on the medium rich in saccharides and disaccharides. Out of polysaccharides tested, only xylan sustained the growth. Fermentation of the hexoses led to the formation of acetate, butyrate, lactate, H2,CO2 and some formate and ethanol. Cell wall peptidoglycan contained meso-diaminopimelic acid. The major fatty acids of the cell wall were C(14:0) and C(16:1c9). The content of G-C pairs in DNA was 31.4 mol%. As phylogenetic analysis has shown, it is closely linked to the members of cluster 1 of Clostridium. It differs from the other species of the genus by the substrates necessary for the growth, products forming as a result of the fermentation and content of the fatty acids in the cell wall. Thus, it was suggested to describe this strain as a new species named Clostridium algoriphilum. Type strain 14D1 was deposited into the Russian Collection of the Microorganisms VKM B-2271T and German Collection of the Microorganisms DSM 16153T .

Bacteria, Anaerobic↗
PubMed2005

Cellulase activity of a haloalkaliphilic anaerobic bacterium, strain Z-7026.

The cellulolytic activity of an alkaliphilic obligate anaerobic bacterium, Z-7026, which was isolated from the microbial community of soda-lake sediments and belongs to the cluster III of Clostridia with low G+C content, was studied. The bacterium was capable of growing in media with cellulose or cellobiose as the sole energy sources. Its maximal growth rate on cellobiose (0.042-0.046 h(-1)) was observed at an initial pH value of 8.5-9.0, whereas the maximal rate of cellulase synthesis, assayed by using a novel fluorimetric approach, was found to be 0.1 h(-1) at pH 8-8.5. Secreted proteins revealed high affinity for cellulose and were represented by two major forms of molecular masses of 75 and 84 kDa, whereas the general protein composition of the precipitated and cellulose-bound preparations was similar to cellulosome subunits of Clostridium thermocellum. The optimum pH of the partially purified enzyme preparation towards both amorphous and crystalline cellulose was in the range 6-9, with more than 70% and less than 50% of maximal activity being retained at pH 9.2 and 5.0, respectively.

Bacteria, Anaerobic↗
PubMed2006

A highly thermostable trehalase from the thermophilic bacterium Rhodothermus marinus.

Trehalases play a central role in the metabolism of trehalose and can be found in a wide variety of organisms. A periplasmic trehalase (alpha,alpha-trehalose glucohydrolase, EC 3.2.1.28) from the thermophilic bacterium Rhodothermus marinus was purified and the respective encoding gene was identified, cloned and overexpressed in Escherichia coli. The recombinant trehalase is a monomeric protein with a molecular mass of 59 kDa. Maximum activity was observed at 88 degrees C and pH 6.5. The recombinant trehalase exhibited a K(m) of 0.16 mM and a V(max) of 81 micromol of trehalose (min)(-1) (mg of protein)(-1) at the optimal temperature for growth of R. marinus (65 degrees C) and pH 6.5. The enzyme was highly specific for trehalose and was inhibited by glucose with a K(i) of 7 mM. This is the most thermostable trehalase ever characterized. Moreover, this is the first report on the identification and characterization of a trehalase from a thermophilic bacterium.

Bacterial Proteins↗
PubMed2001

Cloning of two pectate lyase genes from the marine Antarctic bacterium Pseudoalteromonas haloplanktis strain ANT/505 and characterization of the enzymes.

A marine Antarctic psychrotolerant bacterium (strain ANT/505), isolated from sea ice-covered surface water from the Southern Ocean, showed pectinolytic activity on citrus pectin agar. The sequencing of the 16S rRNA of isolate ANT/505 indicates a taxonomic affiliation to Pseudoalteromonas haloplanktis. The supernatant of this strain showed three different pectinolytic activities after growth on citrus pectin. By activity screening of a genomic DNA library of isolate ANT/505 in Escherichia coli, two different pectinolytic clones could be isolated. Subcloning and sequencing revealed two open reading frames (ORF) of 1,671 and 1,968 nt, corresponding to proteins of 68 and 75 kDa, respectively. The deduced amino acid sequence of the two ORFs showed homology to pectate lyases from Erwinia chrysanthemi and Aspergillus nidulans. The pectate lyases contain signal peptides of 17 and 26 amino acids that were correctly processed after overexpression in E. coli BL21. Both enzymes were purified by anionic exchange chromatography. Maximal enzymatic activities for both pectate lyases were observed at 30 degrees C and a pH range of 9 to 10. The Km values of both lyases for pectate and citrus pectin were 1 g l(-1) and 5 g l(-1), respectively. Calcium was required for activity on pectic substrates, whereas the addition of 1 mM ethylenediaminetetraacetic acid (EDTA) resulted in complete inhibition of the enzymes. These two enzymes represent the first pectate lyases isolated and characterized from a cold-adapted marine bacterium.

Amino Acid Sequence↗
PubMed1998

Purification of a ccb-type quinol oxidase specifically induced in a deep-sea barophilic bacterium, Shewanella sp. strain DB-172F.

We investigated for the first time the respiratory chain system of a deep-sea barophilic bacterium, Shewanella sp. strain DB-172F. A membrane-bound ccb-type quinol oxidase, from cells grown at 60 MPa pressure, was purified to an electrophoretically homogeneous state. The purified enzyme complex consisted of four kinds of subunits with molecular masses of 98, 66, 18.5, and 15kDa, and it contained 0.96 mol of protoheme and 1.95mol of covalently bound heme c per mol of enzyme. Only protoheme in the enzyme reacted with CO and CN-, and the catalytic activity of the enzyme was 50% inhibited by 4 microM CN-. The isoelectric point of the native enzyme complex was determined to be 5.0. This enzyme was specifically induced only under conditions of elevated hydrostatic pressure, and high levels were expressed in cells grown at 60 MPa. The membranes isolated from cells grown at atmospheric pressure (0.1 MPa) exhibited high levels of both cytochrome c oxidase and N,N,N',N'-tetramethyl-p-phenylenediamine (TMPDH2)-oxidase activity. These results suggest the presence of two kinds of respiratory chains regulated in response to pressure in the deep-sea bacterium DB-172F.

Bacteria↗
PubMed1999

The mer operon of the acidophilic bacterium Thiobacillus T3.2 diverges from its Thiobacillus ferrooxidans counterpart.

The chromosomal mercury resistance (mer) region of the acidophilic bacterium Thiobacillus T3.2 was cloned, characterized, and compared to reported homologous sequences. The Thiobacillus T3.2 mer resistance system is organized as an operon that transcribes into a polycistronic mRNA encoding the Hg2+ ion transport MerT and MerP proteins and the mercuric reductase MerA. In contrast to the Thiobacillus ferrooxidans mer determinant, no merC gene was detected. Transcription of structural genes is regulated by the product of the regulatory merR gene. On the basis of sequence data and expression experiments in E. coli, both merTPA and merR transcription units could be located close to each other and in different strands, with their promoters (PTPA and PR, respectively) overlapping the putative MerR binding site in the intergenic operator/promoter (O/P) region. Amino acid sequences of mer gene products were compared to their homologs. Some sequence features, such as the number and position of cysteine residues, are unique for the Mer proteins of this bacterium. Similarities (-10 and -35 boxes are 19bp apart in both PR and PTPA promoters) and differences (inverted repeats in the Thiobacillus T3.2 MerR-binding site are 2bp shorter than in Thiobacillus ferrooxidans) exist between the O/P intergenic regions of both Thiobacilli. In vivo experiments showed inducible expression of mercury resistance in E. coli cells transformed with the entire Thiobacillus T3.2 mer genetic determinant (structural plus regulatory genes), and little or no expression in clones containing only the structural merT, merP, and merA genes.

Amino Acid Sequence↗