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At least 19 recordsLinked to original sources
PubMed1992

Modelling of mixed chemostat cultures of an aerobic bacterium, Comamonas testosteroni, and an anaerobic bacterium, Veillonella alcalescens: comparison with experimental data.

A mathematical model of mixed chemostat cultures of the obligately aerobic bacterium Comamonas testosteroni and the anaerobic bacterium Veillonella alcalescens grown under dual limitation of L-lactate and oxygen was constructed. The model was based on Michaelis-Menten-type kinetics for the consumption of substrates, with noncompetitive inhibition of V. alcalescens by O2. The growth characteristics of the aerobic and anaerobic organisms were determined experimentally with pure cultures of the individual species in (oxygen-limited) chemostats. Using these pure-culture data in the model of the mixed culture resulted in a good description of the actual mixed cultures of the two bacteria. In the actual mixed-culture experiments, coexistence of the two species occurred only when the cultures were oxygen limited. With increasing oxygen supply (the actual oxygen concentration in the culture remaining at less than 0.2 microM), the biomass of C. testosteroni increased, whereas that of V. alcalescens decreased. Apparently, C. testosteroni protected V. alcalescens from inhibition by oxygen by maintaining sufficiently low oxygen concentrations. The model calculations indicated that competition between the aerobic and the anaerobic bacterium for common substrates (L-lactate and oxygen) occurred and that the anaerobe was the better competitor. Analysis of the culture fluid indicated that C. testosteroni grew primarily at the expense of the fermentation products of V. alcalescens, i.e., propionate and acetate. The model further indicated that with different values of several growth parameters (e.g., substrate affinity and/or inhibition constants), the affinity of the aerobic organism for oxygen and the sensitivity of the anaerobic organism for oxygen were the most important properties determining the coexistence of these two physiologically different types of bacteria.

Acetates↗
PubMed2001

Ultrastructure of interaction in alginate beads between the microalga Chlorella vulgaris with its natural associative bacterium Phyllobacterium myrsinacearum and with the plant growth-promoting bacterium Azospirillum brasilense.

Chlorella vulgaris, a microalga often used in wastewater treatment, was coimmobilized and coincubated either with the plant growth-promoting bacterium Azospirillum brasilense, or with its natural associative bacterium Phyllobacterium myrsinacearum, in alginate beads designed for advanced wastewater treatment. Interactions between the microalga and each of the bacterial species were followed using transmission electron microscopy for 10 days. Initially, most of the small cavities within the beads were colonized by microcolonies of only one microorganism, regardless of the bacterial species cocultured with the microalga. Subsequently, the bacterial and microalgal microcolonies merged to form large, mixed colonies within the cavities. At this stage, the effect of bacterial association with the microalga differed depending on the bacterium present. Though the microalga entered a senescence phase in the presence of P. myrsinacearum, it remained in a growth phase in the presence of A. brasilense. This study suggests that there are commensal interactions between the microalga and the two plant associative bacteria, and that with time the bacterial species determined whether the outcome for the microalga is senescence or continuous multiplication.

Alginates↗
PubMedDate not supplied

Carotenoids of an Antarctic psychrotolerant bacterium, Sphingobacterium antarcticus, and a mesophilic bacterium, Sphingobacterium multivorum.

The major carotenoid pigments of an Antarctic psychrotolerant bacterium, Sphingobacterium antarcticus, and a mesophilic bacterium, Sphingobacterium multivorum, were identified as zeaxanthin, beta-cryptoxanthin, and beta-carotene. Analysis was based on ultraviolet-visible spectroscopy, mass spectroscopy, and reversed-phase HPLC. Photoacoustic spectroscopy of intact bacterial cells revealed that the bulk of the pigments in S. antarcticus and S. multivorum was associated with the cell membrane. In vitro studies with synthetic membranes of phosphatidylcholine demonstrated that the major pigment was bound to the membranes and decreased their fluidity. The relative amounts of polar pigments were higher in cells grown at 5 degrees C than in cells grown at 25 degrees C. In the mesophilic strain, the synthesis of polar carotenoids was quantitatively less than that of the psychrotolerant strain.

Antarctic Regions↗
PubMed1998

Characterization of the group 1 and group 2 sigma factors of the green sulfur bacterium Chlorobium tepidum and the green non-sulfur bacterium Chloroflexus aurantiacus.

The group 1 and group 2 sigma70-type sigma factors of the green sulfur bacterium Chlorobium tepidum and of the green nonsulfur bacterium Chloroflexus aurantiacus were cloned and characterized. Cb. tepidum was found to contain one sigma70-type sigma factor; the expression of the gene was analyzed by Northern blot hybridization and primer-extension mapping. Cf. aurantiacus has genes encoding four sigma factors of groups 1 and 2. The expression of these genes was examined in cells grown aerobically and anaerobically. The sigC gene was expressed at approximately equal levels under both conditions, resulting in its designation as the group 1 sigma factor of this organism. The only other detectable transcripts arose from the sigB gene, which was expressed at higher levels during aerobic growth. A phylogenetic tree was obtained using the group 1 sigma factors of Cb. tepidum, Cf. aurantiacus, and diverse eubacteria as the molecular marker. The resulting phylogenetic tree shows that Cb. tepidum and Cf. aurantiacus are related to each other and to the cyanobacteria. The relationship of the group 2 sigma factors of Cf. aurantiacus and the cyanobacteria was more specifically examined phylogenetically. The group 2 sigma factors of Cf. aurantiacus probably arose by gene duplication events after the split of the green nonsulfur bacteria from other photosynthetic eubacteria.

Bacterial Proteins↗
PubMed2004

Characterization of chimeric isocitrate dehydrogenases of a mesophilic nitrogen-fixing bacterium, Azotobacter vinelandii, and a psychrophilic bacterium, Colwellia maris.

Several properties of chimeric enzymes between a mesophilic isocitrate dehydrogenase (IDH) from a nitrogen-fixing bacterium, Azotobacter vinelandii, and a cold-adapted IDH isozyme (IDH-II) from a psychrophilic bacterium, Colwellia maris, were examined. Each of the genes encoding the IDHs was divided into four regions of almost equal lengths, and each region was ligated with different combinations to construct various chimeric genes. The resultant wild-type and chimeric genes were overexpressed in Escherichia coli. The wild-type and chimeric IDHs were classified into three groups based on optimum temperatures for activity of 20 degrees, 30 degrees, and 40 degrees C. The IDHs with a lower optimum temperature were more thermolabile. The optimum temperature and thermostability of the chimeric enzymes decreased on increasing the proportion derived from the cold-adapted IDH-II of C. maris. Furthermore, the C-terminal region of the C. maris IDH-II was suggested to be responsible for its psychrophilic characteristics.

Alteromonadaceae↗
PubMed2004

Differences in malate dehydrogenases from the obligately piezophilic deep-sea bacterium Moritella sp. strain 2D2 and the psychrophilic bacterium Moritella sp. strain 5710.

The gene encoding malate dehydrogenase (MDH) of the obligately piezophilic deep-sea bacterium Moritella sp. strain 2D2 was cloned and sequenced. There were two positions [close to the active site (Ala-180) and in the subunit interaction site (His-229)] with 2D2-specific substitutions. The MDH genes of strain 2D2 and a psychrophilic bacterium Moritella sp. strain 5710 exhibiting the highest sequence similarity were overexpressed in Escherichia coli. The 2D2 MDH was more heat-stable than the 5710 MDH. The apparent Km value at 62.1 MPa for NADH of the 2D2 MDH was higher than that of the 5710 MDH. The 2D2 MDH in which a His-Gln substitution was introduced at position 229 decreased the thermal stability and Km value at 62.1 MPa. The 5710 MDH that was substituted Gln-229 with His increased the thermal stability and Km value at 62.1 MPa. These results indicate that the His residue at position 229 of the 2D2 MDH may play a role in the thermal stability and the MDH function at high pressure.

Amino Acid Sequence↗
PubMed2003

Biosorption of cadmium ions using a photosynthetic bacterium, Rhodobacter sphaeroides S and a marine photosynthetic bacterium, Rhodovulum sp. and their biosorption kinetics.

We examined the biosorption characteristics of cadmium ions onto a photosynthetic bacterium, Rhodobacter sphaeroides S and a marine photosynthetic bacterium Rhodovulum sp. PS88 in a batch culture system. Both photosynthetic bacteria are capable of cadmium removal with 30 g/l sodium chloride and divalent cations (Mg2+ and Ca2+) in the culture medium. In particular, the strain PS88 shows a high removal ratio and high specific removal rate of cadmium ions from the culture medium under aerobic-dark (heterotrophic) and anaerobic-light (photoheterotrophic) conditions. The adsorption of cadmium onto strains PS88 and S is dependent on the cadmium concentration, and follows the Freundlich adsorption isotherm. In addition, biosorption isotherms for cadmium show that the strain PS88 exhibits higher values of the empirical constant for the cadmium adsorption capacity, Kr, than that of the strain S under both aerobic-dark (K(f)=17.44) and anaerobic-light (K(f)=1.270) conditions.

Journal Article↗
PubMed2002

Galactose and lactose genes from the galactose-positive bacterium Streptococcus salivarius and the phylogenetically related galactose-negative bacterium Streptococcus thermophilus: organization, sequence, transcription, and activity of the gal gene products.

Streptococcus salivarius is a lactose- and galactose-positive bacterium that is phylogenetically closely related to Streptococcus thermophilus, a bacterium that metabolizes lactose but not galactose. In this paper, we report a comparative characterization of the S. salivarius and S. thermophilus gal-lac gene clusters. The clusters have the same organization with the order galR (codes for a transcriptional regulator and is transcribed in the opposite direction), galK (galactokinase), galT (galactose-1-P uridylyltransferase), galE (UDP-glucose 4-epimerase), galM (galactose mutarotase), lacS (lactose transporter), and lacZ (beta-galactosidase). An analysis of the nucleotide sequence as well as Northern blotting and primer extension experiments revealed the presence of four promoters located upstream from galR, the gal operon, galM, and the lac operon of S. salivarius. Putative promoters with virtually identical nucleotide sequences were found at the same positions in the S. thermophilus gal-lac gene cluster. An additional putative internal promoter at the 3' end of galT was found in S. thermophilus but not in S. salivarius. The results clearly indicated that the gal-lac gene cluster was efficiently transcribed in both species. The Shine-Dalgarno sequences of galT and galE were identical in both species, whereas the ribosome binding site of S. thermophilus galK differed from that of S. salivarius by two nucleotides, suggesting that the S. thermophilus galK gene might be poorly translated. This was confirmed by measurements of enzyme activities.

Base Sequence↗
PubMed1991

Expression of the gene encoding cytochrome c3 from the sulfate-reducing bacterium Desulfovibrio vulgaris in the purple photosynthetic bacterium Rhodobacter sphaeroides.

The gene encoding cytochrome c3 (cyc-gene) from Desulfovibrio vulgaris (Hildenborough) was cloned by G. Voordouw and S. Brenner (1986, Eur. J. Biochem. 159, 347-351). The gene was expressed in Escherichia coli but only the apoprotein was observed (W. Pollock, P. Chemerika, M. Forrest, J. Beatty, and G. Voordouw, 1989, J. Gen. Microbiol. 135, 2319-2328). In this study, the cyc-gene was cloned into the broad host range vector pRK404 and then introduced into the purple photosynthetic bacterium Rhodobacter sphaeroides. Cells grown anaerobically produced a significant amount of recombinant cytochrome c3. The purified protein contains four hemes and the N-terminal protein sequence is identical to the published sequence of the native cytochrome c3. Thus, R. sphaeroides was able to produce the mature cytochrome c3 by combining the four steps of protein synthesis, exporting the protein across the membrane, cleaving the signal peptide, and inserting four hemes. It appears that the D. vulgaris promoter is not very efficiently used by R. sphaeroides. However, replacement of the promoter with a R. sphaeroides promoter should result in cytochrome c3 overproduction.

Cloning, Molecular↗
PubMed2004

Chlorate and nitrate reduction pathways are separately induced in the perchlorate-respiring bacterium Dechlorosoma sp. KJ and the chlorate-respiring bacterium Pseudomonas sp. PDA.

The effect of nitrate on perchlorate and chlorate reduction by perchlorate-respiring bacteria (PRB), and on chlorate reduction by chlorate-respiring bacteria (CRB), is not well understood, particularly with respect to the induction of pathways used to degrade these different chemicals. Based on kinetic data obtained in a series of batch tests, we determined that perchlorate respiratory enzymes were inducible (by chlorate or perchlorate) and separate from those used for denitrification by PRB strain Dechlorosoma sp. KJ. Aerobically grown cultures of KJ had lag times of greater than 0.3-2 days when transferred to a medium containing only perchlorate, chlorate, or nitrate as an electron acceptor. There were no lag times for transfers between identical media. Washed cells reduced very little nitrate (<10%) when grown only on chlorate or perchlorate. When grown on nitrate, they degraded little chlorate or perchlorate. The same lack of activity with these electron acceptors was also observed using cell extracts and methyl viologen as an electron carrier, indicating a lack of reactivity was not due to failure of the chemical to diffuse into the cell. Taken together, these results indicated that enzymes for perchlorate and nitrate reduction are separately expressed in strain KJ. The presence of small amounts of nitrate in contaminated groundwater may actually help to increase rates of perchlorate reduction once the nitrate is completely removed. When strain KJ was pre-grown on nitrate and perchlorate, perchlorate degradation (in the absence of nitrate) was more rapid compared to cells grown only on perchlorate. Pseudomonas sp. PDA was unable to degrade perchlorate or grow using nitrate, and the induction of enzymes necessary for chlorate respiration differed for strains KJ and PDA. While chlorate reductase and chlorite dismutase activity were induced in KJ by chlorate or perchlorate under anaerobic conditions, these two enzymes were constitutively expressed by PDA under anaerobic and aerobic conditions independent of the presence of chlorate. To our knowledge, this is the first report of constitutive expression of both chlorate reductase and chlorite dismutase in a bacterium.

Bacteria, Anaerobic↗
PubMed1996

Clostridium ultunense sp. nov., a mesophilic bacterium oxidizing acetate in syntrophic association with a hydrogenotrophic methanogenic bacterium.

A syntrophic acetate-oxidizing bacterium, strain BST (T = type strain), was isolated from a previously described mesophilic triculture that was able to syntrophically oxidize acetate and form methane in stoichiometric amounts. Strain BST was isolated with substrates typically utilized by homoacetogenic bacteria. Strain BST was a spore-forming, gram-positive, rod-shaped organism which utilized formate, glucose, ethylene glycol, cysteine, betaine, and pyruvate. Acetate and sometimes formate were the main fermentation products. Small amounts of alanine were also produced from glucose, betaine, and cysteine. Strain BST grew optimally at 37 degrees C and pH 7. The G+C content of the DNA of strain BST was 32 mol%. A 16S rRNA sequence analysis revealed that strain BST was a member of a new species of the genus Clostridium. We propose the name Clostridium ultunense for this organism; strain BS is the type strain of C. ultunense.

Acetates↗
PubMed2006

Construction of a stable expression vector for Leifsonia xyli subsp. cynodontis and its application in studying the effect of the bacterium as an endophytic bacterium in rice.

To study the possibility of utilizing genetically engineered Leifsonia xyli subsp. cynodontis (Lxc) as an endophytic bacterium in rice, we constructed an Escherichia coli-Lxc shuttle vector, pLGUS, containing a beta-glucuronidase reporter gene, which was stable both in vitro and in vivo. Lxc grows and expresses the beta-glucuronidase reporter gene in all parts of rice, except for seed. A 2-year field study using three rice varieties from China showed that Lxc inoculation did not have a negative effect on the growth and yield of any of these varieties. Therefore, Lxc has the potential to be used as a benign endophyte for the expression of foreign genes in rice.

Actinomycetales↗
PubMed1994

Bacterium-host cell interactions at the cellular level: fluorescent labeling of bacteria and analysis of short-term bacterium-phagocyte interaction by flow cytometry.

Flow cytometry is a potentially powerful tool for analyzing the interactions of facultative intracellular bacteria and macrophages on a cellular level, particularly when fluorochromes are used to label the bacteria. We labeled Listeria monocytogenes and Salmonella typhimurium with a lipophilic dye, PKH-2, and used flow cytometry to investigate phagocytosis by J774A.1 cells and short-term bacterial survival. Labeled and unlabeled bacteria were identical in terms of viability, growth kinetics, and survival within macrophages, although recovery per macrophage was much greater for L. monocytogenes than for S. typhimurium. Using L. monocytogenes as a prototypical facultative intracellular bacterium, we estimated bacterial survival during phagocytosis on the basis of linear fluorescence measurements of infected J774A.1 cells and recovery of L. monocytogenes from sorted cells. The lower percentage of surviving L. monocytogenes in macrophages containing higher bacterial loads indicated the accumulation of nonviable bacteria within phagocytes. Removal of the external source of viable bacteria by washes and gentamicin treatment reduced the percentage of surviving intracellular L. monocytogenes to a baseline level, and all baseline levels were similar, regardless of bacterial load. Listeria enrichment recoveries, derived from individually sorted J774A.1 cells, demonstrated the heterogeneity of macrophages in intracellular bacterial survival, especially within heavily infected cells. These results indicated that survival of L. monocytogenes was dependent on the adaptations of a small fraction of bacteria within a population of macrophages which permit intracellular growth.

Adaptation, Physiological↗
PubMed2002

Commensal relationship between a sheath-forming bacterium, Sphaerotilus natans, and a sheath-degrading bacterium, Paenibacillus sp.

Paenibacillus sp. strain TB is capable of degrading the sheath prepared from a sheathed bacterium, Sphaerotilus natans. S. natans was able to grow alone on casamino acids but strain TB was not. Cocultivation of strain TB and S. natans was examined in a medium supplemented with casamino acids as a growth substrate. The growth of strain TB was observed when the sheath was supplied to the medium or in cocultivation with S. natans. The phospholipid amount reached a maximum after 24 h of cocultivation and subsequently kept almost the same level for 96 h. The sheath amount also reached a maximum after 24 h and then gradually declined. The cell concentration of strain TB increased throughout the cocultivation. By competitive PCR targeted for amplification of a part of 16S rDNA, the abundance ratio (S. natans/strain TB) of 6.7 was obtained at 72 h. Almost no growth of strain TB was detected in a coculture with a sheath-less mutant of S. natans. The evidence allows the conclusion that strain TB grew by utilizing the intact sheath in coculture with S. natans.

Bacillus↗
PubMed1980

"Pittsburgh pneumonia agent": a bacterium phenotypically similar to Legionella pneumophila and identical to the TATLOCK bacterium.

The "Pittsburgh pneumonia agent," isolated by Pasculle and co-workers from human lung tissue, has been cultured on artificial media and characterized. The "Pittsburgh" bacterium and the TATLOCK and HEBA bacteria have identical cultural, biochemical, and antigenic characteristics. They also have the same cellular fatty-acid composition, and DNA relatedness indicates that they belong to the same species.

Antigens, Bacterial↗
PubMed2002

[Phylogenetic analysis of intestinal bacterium using the distribution of intestinal bacterium in cyprinidate fishes and 16S DNA sequence data set].

There is a complex- and multi-effect for interdependent survival between intestinal- microorganisms and hosts. The symbiosis or coevolution that results from this effect for interdependent survival is used to reveal the phylogenies of hosts as well as intestinal microorganisms. The symbiosis or coevolution between intestinal microorganisms and hosts has been generated by interactive natural selection occurred between them. The symbiosis information that has been formed by interactive natural selection during a long evolutionary process must be recorded in DNA sequences. According to this point of view,we analyzed the phylogeny of 9 intestinal bacteria genera using their contents in intestines of 8 Cyrinidate species. At the same time,we fetched the 16S rRNA gene DNA sequences of 43 intestinal bacteria species being included in these nine genera of six intestinal families from GeneBank and constructed phylogenetic trees by NJ and MP methods. The NJ tree and MP tree have the same topologic configuration and are identical with the classical phylogenetic tree. Both the trees of 16S rRNA gene separated 43 bacteria species into gram-negative bacteria group and the gram-positive bacteria group,which are the first branches. Each of the first branches (groups) made again 6 subbranches (subgroups) where each subbranch is a family.Especially,the subbranch (subgroup) of enterobacteriaceace made again four small branches as genus taxon. This tree also shows that bacilliform bacterium is distinct from each other in the NJ and MP trees. After all species on the tree are merged,the topological configuration of the unrooted tree of 16S gene is closed to that of the host range unrooted tree.However,the position of bacillus is greatly changed on both the unrooted trees. The difference can be found if we increase the examination level and extend the hosts examed.

English Abstract↗