Molecular cloning of isomaltotrio-dextranase gene from Brevibacterium fuscum var. dextranlyticum strain 0407 and its expression in Escherichia coli.
(9/240)
The gene encoding an extracellular isomaltotrio-dextranase (IMTD), designed dexT, was cloned from the chromosomal DNA of Brevibacterium fuscum var. dextranlyticum strain 0407, and expressed in Escherichia coli. A single open reading frame consisting of 1923 base pairs that encoded a polypeptide composed of a signal peptide of 37 amino acids and a mature protein of 604 amino acids (M(r), 68,300) was found. The primary structure had no significant similarity with the structure of two other reported exo-type dextranases (glucodextranase and isomalto-dextranase), but had high similarity with that of an endo-dextranase isolated from Arthrobacter sp. Transformed E. coli cells carrying the gene encoding mature protein of IMTD overproduced IMTD under the control of the T7 phage promoter induced by IPTG. The purified recombinant enzyme showed the same optimum pH, lower specific activity, and similar hydrolytic pattern, as to those of native IMTD. (+info)
Brevibacterium avium sp. nov., isolated from poultry.
(10/240)
Two strains of a Brevibacterium-like bacterium originating from bumble-foot lesions of domestic fowls were subjected to a polyphasic taxonomic study. The phenotypic characteristics of the bacterium were consistent with its assignment to the genus Brevibacterium although comparative 16S rRNA gene sequencing showed that the organism represents a distinct subline within the genus. Chromosomal DNA-DNA pairing studies confirmed that the unidentified bacterium was genomically distinct and worthy of separate species status. Based on the phenotypic and genotypic distinctiveness of the bacterium from poultry, a new species, Brevibacterium avium, is proposed. The type strain of Brevibacterium avium is NCIMB 703055T. (+info)
Use of an enzyme-linked lectinsorbent assay to monitor the shift in polysaccharide composition in bacterial biofilms.
(11/240)
An enzyme-linked lectinsorbent assay (ELLA) was developed for quantification and characterization of extracellular polysaccharides produced by 1- and 4-day biofilms of 10 bacterial strains isolated from food industry premises. Peroxidase-labeled concanavalin A (ConA) and wheat germ agglutinin (WGA) were used, as they specifically bind to saccharide residues most frequently encountered in biofilms matrices: D-glucose or D-mannose for ConA and N-acetyl-D-glucosamine or N-acetylneuraminic acid for WGA. The ELLA applied to 1- and 4-day biofilms colonizing wells of microtiter plates was able to detect that for Stenotrophomonas maltophilia and to a lesser extent Staphylococcus sciuri, the increase in production of exopolysaccharides over time was not the same for sugars binding with ConA and those binding with WGA. Differences in extracellular polysaccharides produced were observed among strains belonging to the same species. These results demonstrate that ELLA is a useful tool not only for rapid characterization of biofilm extracellular polysaccharides but also, in studies of individual strains, for detection of changes over time in the proportion of the exopolysaccharidic component within the polymeric matrix. (+info)
Salvage pathway for NAD biosynthesis in Brevibacterium ammoniagenes: regulatory properties of triphosphate-dependent nicotinate phosphoribosyltransferase.
(12/240)
As the rate-limiting enzyme, catalyzing the first reaction in NAD salvage synthesis, nicotinate phosphoribosyltransferase (NAPRTase, EC 2.4.2.11) is of important interest for studies of intracellular pyridine nucleotide pool regulation. We have purified NAPRTase 520-fold from Brevibacterium ammoniagenes ATCC 6872 without using an over-expression system by applying acid treatment, salt fractionation, Ca-phosphate gel treatment, anion exchange column chromatography and size-exclusion gel filtration. Unlike this enzyme from other sources, B. ammoniagenes NAPRTase was found to be controlled by the feedback inhibition by the end product NAD with K(i)=0.7+/-0.1 mM. The reaction products, pyrophosphate and nicotinate mononucleotide, also decreased the enzyme activity, as did other intermediates of NAD synthesis, such as AMP, ADP and a NAD direct precursor, nicotinate adenine dinucleotide or deamido NAD. The enzyme was observed to require a nucleoside triphosphate for its activity and showed the maximum affinity for ATP. The specificity, however, turned out to be poor, and ATP could be substituted by other nucleoside triphosphates as well as by sodium triphosphate. The kinetic characteristics of the enzyme are reported. For the first time, our data have experimentally revealed such complicated stimulatory and inhibitory effects by the intermediates of NAD biosynthesis on one of its salvage enzymes, NAPRTase. On the basis of these data, the key role of NAPRTase is discussed in light of the regulation of NAD metabolism in B. ammoniagenes. (+info)
Development of an improved assay for purine nucleoside kinase activity in cell extracts and detection of inosine kinase activity in Brevibacterium acetylicum ATCC 953, related species, and Corynebacterium flaccumfaciens ATCC 6887.
(13/240)
An improved assay was developed to detect direct purine nucleoside phosphorylating activity in cell-free extracts. Direct inosine phosphorylating activity was detected in 2 of 70 species tested. Both activities, which depended on magnesium ion and ATP, phosphorylated a hydroxyl group at the 5' position of inosine. The new assay was shown to be useful for screening of direct purine nucleoside phosphorylating activity and have the potential to detect inosine kinase in the presence of a background of nucleoside phosphorylase and purine phosphoribosyltransferase activities. Previously, the latter two activities made it difficult to correctly detect direct phosphorylation of inosine by inosine kinase. (+info)
Simultaneous identification of two cyclohexanone oxidation genes from an environmental Brevibacterium isolate using mRNA differential display.
(14/240)
The technique of mRNA differential display was used to identify simultaneously two metabolic genes involved in the degradation of cyclohexanone in a new halotolerant Brevibacterium environmental isolate. In a strategy based only on the knowledge that cyclohexanone oxidation was inducible in this strain, the mRNA population of cells exposed to cyclohexanone was compared to that of control cells using reverse transcription-PCR reactions primed with a collection of 81 arbitrary oligonucleotides. Three DNA fragments encoding segments of flavin monooxygenases were isolated with this technique, leading to the identification of the genes of two distinct cyclohexanone monooxygenases, the enzymes responsible for the oxidation of cyclohexanone. Each monooxygenase was expressed in Escherichia coli and characterized. This work validates the application of mRNA differential display for the discovery of new microbial metabolic genes. (+info)
Brevibacterium casei sepsis in an 18-year-old female with AIDS.
(15/240)
Brevibacterium sp. was isolated from the blood of an acutely ill 18-year-old female with AIDS. The isolate was identified as Brevibacterium casei by use of carbohydrate assimilation tests. Treatment was successful with intravenously administered ciprofloxacin. To our knowledge, this is the first report of sepsis caused by B. casei in a human immunodeficiency virus-infected patient. (+info)
Trehalose synthesis by sequential reactions of recombinant maltooligosyltrehalose synthase and maltooligosyltrehalose trehalohydrolase from Brevibacterium helvolum.
(16/240)
A DNA fragment encoding two enzymes leading to trehalose biosynthesis, maltooligosyltrehalose synthase (BvMTS) and maltooligosyltrehalose trehalohydrolase (BvMTH), was cloned from the nonpathogenic bacterium Brevibacterium helvolum. The open reading frames for the two proteins are 2,331 and 1,770 bp long, respectively, and overlap by four nucleotides. Recombinant BvMTS, BvMTH, and fusion gene BvMTSH, constructed by insertion of an adenylate in the overlapping region, were expressed in Escherichia coli. Purified BvMTS protein catalyzed conversion of maltopentaose to maltotriosyltrehalose, which was further hydrolyzed by BvMTH protein to produce trehalose and maltotriose. The enzymes shortened maltooligosaccharides by two glucose units per cycle of sequential reactions and released trehalose. Maltotriose and maltose were not catalyzed further and thus remained in the reaction mixtures depending on whether the substrates had an odd or even number of glucose units. The bifunctional in-frame fusion enzyme, BvMTSH, catalyzed the sequential reactions more efficiently than an equimolar mixture of the two individual enzymes did, presumably due to a proximity effect on the catalytic sites of the enzymes. The recombinant enzymes produced trehalose from soluble starch, an abundant natural source for trehalose production. Addition of alpha-amylase to the enzyme reaction mixture dramatically increased trehalose production by partial hydrolysis of the starch to provide more reducing ends accessible to the BvMTS catalytic sites. (+info)