Characterization of bacteriophage BFK20 from Brevibacterium flavum.
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Bacteriophage BFK20 was isolated from a Brevibacterium flavum strain that had become contaminated during industrial fermentation. BFK20 has a polyhedral head 50 nm wide and a non-contractile tail 200 nm long and 10 nm in diameter. The genome of this bacteriophage consists of a linear double stranded DNA molecule of 44-45 kb with cohesive ends. The capsid of phage BFK20 contains nine polypeptides with molecular masses from 22.0-108.0 kDa. BFK20 DNA was used as a donor for fragments carrying promoters and transcription-terminators. (+info)
Gulosibacter molinativorax gen. nov., sp. nov., a molinate-degrading bacterium, and classification of 'Brevibacterium helvolum' DSM 20419 as Pseudoclavibacter helvolus gen. nov., sp. nov.
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A Gram-positive, molinate-degrading bacterium, strain ON4(T) (=DSM 13485(T)=LMG 21909(T)), was isolated from a mixed bacterial culture able to mineralize the herbicide molinate. The strain was strictly aerobic, oxidase- and catalase-positive and non-acid-fast, with a growth temperature of 10-41 degrees C. It contained the major menaquinone MK-9 and a cell-wall peptidoglycan based on D-ornithine. 16S rDNA sequence analysis revealed that the strain formed a distinct line of descent in the family Microbacteriaceae, showing the highest 16S rDNA similarity ( approximately 95 %) to members of the genus Curtobacterium and 'Brevibacterium helvolum' DSM 20419 (=ATCC 13715). The latter was reported to have the cell-wall peptidoglycan type B2gamma and the major menaquinone MK-9, which are typical of Clavibacter, but it is clearly separated from this genus at the phylogenetic level. Based on low values of 16S rDNA sequence similarity to previously described genera and their distinctive phenotypic characteristics, it is proposed that strains ON4(T) and 'B. helvolum' DSM 20419 be classified as two novel genera and species, with the respective names Gulosibacter molinativorax gen. nov., sp. nov. and Pseudoclavibater helvolus gen. nov., sp. nov. (+info)
Identification of a novel Brevibacterium species isolated from humans and description of Brevibacterium sanguinis sp. nov.
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Six coryneforms isolated from blood and dialysate fluid were phenotypically similar to Brevibacterium casei, but 16S rRNA gene sequencing and DNA-DNA hybridization indicate that they belong to a new species for which the name Brevibacterium sanguinis is proposed. (+info)
Brevibacterium picturae sp. nov., isolated from a damaged mural painting at the Saint-Catherine chapel (Castle Herberstein, Austria).
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Three strains showing highly similar (GTG)5-PCR patterns were isolated from a heavily damaged mural painting at the Saint-Catherine chapel (Castle Herberstein, Austria). On the basis of 16S rRNA gene sequence similarity, the strains were attributed to Brevibacterium, with Brevibacterium casei (96.7 %), Brevibacterium iodinum (96.7 %) and Brevibacterium linens (96.6 %) as the closest related species. Chemotaxonomic data [peptidoglycan contains meso-diaminopimelic acid; mycolic acids absent; MK-8(H2) as the major menaquinone; polar lipids phosphatidylglycerol and diphosphatidylglycerol present; anteiso-C(15 : 0) and anteiso-C(17 : 0) as major fatty acids] supported the affiliation of the strains to the genus Brevibacterium. Additional physiological and biochemical tests confirmed the taxonomic position of the strains and allowed phenotypic differentiation from Brevibacterium species with validly published names. The isolates from the mural painting, therefore, represent a novel species, for which the name Brevibacterium picturae sp. nov. is proposed, with LMG 22061T (= DSM 16132T) as the type strain. (+info)
Fatty acid production from amino acids and alpha-keto acids by Brevibacterium linens BL2.
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Low concentrations of branched-chain fatty acids, such as isobutyric and isovaleric acids, develop during the ripening of hard cheeses and contribute to the beneficial flavor profile. Catabolism of amino acids, such as branched-chain amino acids, by bacteria via aminotransferase reactions and alpha-keto acids is one mechanism to generate these flavorful compounds; however, metabolism of alpha-keto acids to flavor-associated compounds is controversial. The objective of this study was to determine the ability of Brevibacterium linens BL2 to produce fatty acids from amino acids and alpha-keto acids and determine the occurrence of the likely genes in the draft genome sequence. BL2 catabolized amino acids to fatty acids only under carbohydrate starvation conditions. The primary fatty acid end products from leucine were isovaleric acid, acetic acid, and propionic acid. In contrast, logarithmic-phase cells of BL2 produced fatty acids from alpha-keto acids only. BL2 also converted alpha-keto acids to branched-chain fatty acids after carbohydrate starvation was achieved. At least 100 genes are potentially involved in five different metabolic pathways. The genome of B. linens ATCC 9174 contained these genes for production and degradation of fatty acids. These data indicate that brevibacteria have the ability to produce fatty acids from amino and alpha-keto acids and that carbon metabolism is important in regulating this event. (+info)
Brevibacterium celere sp. nov., isolated from degraded thallus of a brown alga.
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Two whitish yellow, Gram-positive, non-motile, aerobic bacteria were isolated from enrichment culture during degradation of the thallus of the brown alga Fucus evanescens. The bacteria studied were chemo-organotrophic, mesophilic and grew well on nutrient media containing up to 15 % (w/v) NaCl. The DNA G+C content was 61 mol%. The two isolates exhibited a conspecific DNA-DNA relatedness value of 98 %, indicating that they belong to the same species. A comparative analysis of 16S rRNA gene sequences revealed that strain KMM 3637(T) formed a distinct phyletic lineage in the genus Brevibacterium (family Brevibacteriaceae, class Actinobacteria) and showed the highest sequence similarity (about 97 %) to Brevibacterium casei. DNA-DNA hybridization experiments demonstrated 45 % binding with the DNA of B. casei DSM 20657(T). Physiological and chemotaxonomic characteristics (meso-diaminopimelic acid in the peptidoglycan, major cellular fatty acids 15 : 0ai and 17 : 0ai) of the bacteria studied were consistent with the genomic and phylogenetic data. On the basis of the results of this study, a novel species, Brevibacterium celere sp. nov., is proposed. The type strain is KMM 3637(T) (=DSM 15453(T)=ATCC BAA-809(T)). (+info)
Identification and functional analysis of the gene encoding methionine-gamma-lyase in Brevibacterium linens.
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The enzymatic degradation of L-methionine and subsequent formation of volatile sulfur compounds (VSCs) is believed to be essential for flavor development in cheese. L-methionine-gamma-lyase (MGL) can convert L-methionine to methanethiol (MTL), alpha-ketobutyrate, and ammonia. The mgl gene encoding MGL was cloned from the type strain Brevibacterium linens ATCC 9175 known to produce copious amounts of MTL and related VSCs. The disruption of the mgl gene, achieved in strain ATCC 9175, resulted in a 62% decrease in thiol-producing activity and a 97% decrease in total VSC production in the knockout strain. Our work shows that L-methionine degradation via gamma-elimination is a key step in the formation of VSCs in B. linens. (+info)
Dissecting the structural determinants of the stability of cholesterol oxidase containing covalently bound flavin.
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Cholesterol oxidase from Brevibacterium sterolicum is a monomeric flavoenzyme catalyzing the oxidation and isomerization of cholesterol to cholest-4-en-3-one. This protein is a class II cholesterol oxidases, with the FAD cofactor covalently linked to the enzyme through the His(69) residue. In this work, unfolding of wild-type cholesterol oxidase was compared with that of a H69A mutant, which does not covalently bind the flavin cofactor. The two protein forms do not show significant differences in their overall topology, but the urea-induced unfolding of the H69A mutant occurred at significant lower urea concentrations than wild-type (approximately 3 versus approximately 5 M, respectively), and the mutant protein had a melting temperature approximately 10-15 degrees C lower than wild-type in thermal denaturation experiments. The different sensitivity of the various spectroscopic features used to monitor protein unfolding indicated that in both proteins a two-step (three-state) process occurs. The presence of an intermediate was more evident for the H69A mutant at 2 m urea, where catalytic activity and tertiary structure were lost, and new hydrophobic patches were exposed on the protein surface, resulting in protein aggregation. Comparative analysis of the changes occurring upon urea and thermal treatment of the wild-type and H69A protein showed a good correlation between protein instability and the elimination of the covalent link between the flavin and the protein. This covalent bond represents a structural device to modify the flavin redox potentials and stabilize the tertiary structure of cholesterol oxidase, thus pointing to a specific meaning of the flavin binding mode in enzymes that carry out the same reaction in pathogenic versus non-pathogenic bacteria. (+info)