Corynebacterium terpenotabidum sp. nov., a bacterium capable of degrading squalene.
The taxonomic status of Arthrobacter sp. Y-11T, which was described as a squalene-degrading bacterium, was investigated by chemotaxonomic and genetic methods. The strain possesses wall chemotype IV, MK-9(H2) as the predominant menaquinone, mycolic acids, and straight-chain, saturated and monounsaturated fatty acids, with considerable amounts of tuberculostearic acid. The DNA G+C content is 67.5 mol%. 16S rRNA gene sequence analysis and quantitative DNA-DNA hybridization experiments provided strong evidence that strain Y-11T represents a new species within the genus Corynebacterium, for which the name Corynebacterium terpenotabidum sp. nov. is proposed. The type strain of C. terpenotabidum is strain Y-11T (= IFO 14764T). (+info)
Identification of mechanosensitive ion channels in the cytoplasmic membrane of Corynebacterium glutamicum.
Patch-clamp experiments performed on membrane fragments of Corynebacterium glutamicum fused into giant liposomes revealed the presence of two different stretch-activated conductances, 600 to 700 pS and 1,200 to 1,400 pS in 0.1 M KCl, that exhibited the same characteristics in terms of kinetics, ion selectivity, and voltage dependence. (+info)
Sex differences in susceptibility of ICR mice to oral infection with Corynebacterium kutscheri.
Sex difference in susceptibility to oral infection with Corynebacterium (C.) kutscheri was experimentally studied in ICR mice. Immature (4-week-old) and adult (14-week-old) mice were inoculated with two infecting doses of C. kutscheri, and necropsied for bacteriological and serological survey 4 weeks after the bacterial infection. No macroscopic lesions at necropsy were demonstrated, except for one adult male given 10(9) bacteria. In immature mice, C. Kutscheri isolated from the oral cavity and cecum with FNC agar, were recovered in only 40.0% of female mice but in 90.0% of male mice given 10(6) bacteria (p < 0.05), and in only 55.6% of female mice but in 80.0% male mice given 10(8) bacteria. In adult mice given 10(9) bacteria, the organism were recovered in only 45.5% of female mice but in 90.9% of male mice (p < 0.05), furthermore, the mean number of organisms in the cecum of male mice harboring the organism was significantly higher than that in females (p < 0.01). Castration caused an increase in host resistance in adult male mice. These results indicated that ICR male mice were more susceptible than females, in terms of bacterial colonization in the cecum and the oral cavity, to oral infection with C. kutscheri. (+info)
Identification of nonlipophilic corynebacteria isolated from dairy cows with mastitis.
Nonlipophilic corynebacteria associated with clinical and subclinical mastitis in dairy cows were found to belong to four species: Corynebacterium amycolatum, Corynebacterium ulcerans, Corynebacterium pseudotuberculosis, and Corynebacterium minutissimum. These species may easily be confused. However, clear-cut differences between C. ulcerans and C. pseudotuberculosis were found in their acid production from maltotriose and ethylene glycol, susceptibility to vibriostatic agent O129, and alkaline phosphatase. Absence of growth at 20 degrees C and lack of alpha-glucosidase and 4MU-alpha-D-glycoside hydrolysis activity differentiated C. amycolatum from C. pseudotuberculosis and C. ulcerans. The mastitis C. pseudotuberculosis strains differed from the biovar equi and ovis reference strains and from caprine field strains in their colony morphologies and in their reduced inhibitory activity on staphylococcal beta-hemolysin. C. amycolatum was the most frequently isolated nonlipophilic corynebacterium. (+info)
Cloning, sequence analysis, expression and inactivation of the Corynebacterium glutamicum pta-ack operon encoding phosphotransacetylase and acetate kinase.
The Corynebacterium glutamicum ack and pta genes encoding the acetate-activating enzymes acetate kinase and phosphotransacetylase were isolated, subcloned on a plasmid and re-introduced into Corynebacterium glutamicum. Relative to the wild-type, the recombinant strains showed about tenfold higher specific activities of both enzymes. Sequence analysis of a 3657 bp DNA fragment revealed that the ack and pta genes are contiguous in the corynebacterial chromosome, with pta upstream and the last nucleotide of the pta stop codon (TAA) overlapping the first of the ack start codon (ATG). The predicted gene product of pta consists of 329 amino acids (Mr 35242), that of ack consists of 397 amino acids (Mr 43098) and the amino acid sequences of the two polypeptides show up to 60 % (phosphotransacetylase) and 53% (acetate kinase) identity in comparison with respective enzymes from other organisms. Northern (RNA) blot hybridizations using pta- and ack-specific probes and transcriptional cat fusion experiments revealed that the two genes are transcribed as a 2.5 kb bicistronic mRNA and that the expression of this operon is induced when Corynebacterium glutamicum grows on acetate instead of glucose as a carbon source. Directed inactivation of the chromosomal pta and ack genes led to the absence of detectable phosphotransacetylase and acetate kinase activity in the respective mutants and to their inability to grow on acetate. These data indicate that no isoenzymes of acetate kinase and phosphotransacetylase are present in Corynebacterium glutamicum and that a functional acetate kinase/phosphotransacetylase pathway is essential for growth of this organism on acetate. (+info)
Expression of the Corynebacterium glutamicum panD gene encoding L-aspartate-alpha-decarboxylase leads to pantothenate overproduction in Escherichia coli.
The Corynebacterium glutamicum panD gene was identified by functional complementation of an Escherichia coli panD mutant strain. Sequence analysis revealed that the coding region of panD comprises 411 bp and specifies a protein of 136 amino acid residues with a deduced molecular mass of 14.1 kDa. A defined C. glutamicum panD mutant completely lacked L-aspartate-alpha-decarboxylase activity and exhibited beta-alanine auxotrophy. The C. glutamicum panD (panDC. g.) as well as the E. coli panD (panDE.c.) genes were cloned into a bifunctional expression plasmid to allow gene analysis in C. glutamicum as well as in E. coli. The enhanced expression of panDC.g. in C. glutamicum resulted in the formation of two distinct proteins in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, leading to the assumption that the panDC.g. gene product is proteolytically processed into two subunits. By increased expression of panDC.g. in C. glutamicum, the activity of L-aspartate-alpha-decarboxylase was 288-fold increased, whereas the panDE.c. gene resulted only in a 4-fold enhancement. The similar experiment performed in E. coli revealed that panDC.g. achieved a 41-fold increase and that panDE.c. achieved a 3-fold increase of enzyme activity. The effect of the panDC.g. and panDE.c. gene expression in E. coli was studied with a view to pantothenate accumulation. Only by expression of the panDC.g. gene was sufficient beta-alanine produced to abolish its limiting effect on pantothenate production. In cultures expressing the panDE.c. gene, the maximal pantothenate production was still dependent on external beta-alanine supplementation. The enhanced expression of panDC.g. in E. coli yielded the highest amount of pantothenate in the culture medium, with a specific productivity of 140 ng of pantothenate mg (dry weight)-1 h-1. (+info)
Microbiological degradation of bile acids. The conjugation of a certain cholic acid metabolite with amino acids in Corynebacterium equi.
1. (4R)-4[4alpha-(2-Carboxyethyl)-3aalpha-hexahydro-7abeta-methyl-5-oxoindan-1beta-y l]valeric acid (II) could not be utilized by Arthrobacter simplex, even though the acid was one of the metabolites formed from cholic acid (I) by this organism. Therefore the further degradation of the acid (II) by Corynebacterium equi was investigated to identify the intermediates involved in the cholic acid degradation. 2. The organism, cultured in a medium containing the acid (II) as the sole source of carbon, produced unexpected metabolites, the conjugates of this original acid (II) with amino acids or their derivatives, although the yield was very low. These new metabolites were isolated and identified by chemical synthesis as the Na-((4R)-4-[4alpha-(2-carboxyethyl)-3a alpha-hexahydro-7a beta-methyl-5-oxoindan-1 beta-yl]-valeryl) derivatives of L-alanine, glutamic acid, O-acetylhomoserine and glutamine, i.e. compounds (IIIa), (IIIb), (IIId) respectively. 3. The possibility that the bacterial synthetic reaction observed in the acid (II) metabolism with C. equi is analogous to peptide conjugation known in both animals and higher plants is discussed. A possible mechanism for this bacterial conjugation is also considered. (+info)
Site-specific integration of corynephage phi16: construction of an integration vector.
Phi16, a temperate phage induced from Corynebacterium glutamicum ATCC 21792, lysogenizes its host via site-specific recombination. The phage attachment site, attP, was located to a 6.5 kb BamHI fragment of the phi16 genome. This fragment also contained phi16 integrative functions. The minimal phage DNA fragment required for integration was defined. This 1630 bp region contained a large open reading frame, int, encoding a protein of 416 amino acids with similarity in its carboxyl-terminal domain to tyrosine recombinases and particularly to the Xer recombinases. The comparison of the nucleotide sequences of attB, attL, attR, and attP identified a common 29 bp sequence, the core sequence. It lies 11 bp downstream of the 3' end of the integrase gene. phi16 integrase was shown to catalyse site-specific integration in trans to attP with an efficiency of 5x10(3) integrants per microg DNA. The integrating fragment catalysed integration in several Corynebacterium strains that are not infected by phi16, thus enlarging the host spectrum of integrating vectors derived from phi16. In these strains, the phi16 attB site was located in a conserved intergenic region and lies downstream of a clp gene. (+info)