( 2004 )
Gene cloning and characterization of a Bacillus vietnamensis metalloprotease.
PMID : 15277758 :
A Bacillus vietnamensis metalloprotease (BVMP) with high affinity toward collagen was isolated and purified from the culture supernatant of Bacillus vietnamensis 11-4 occurring in Vietnamese fish sauces. The BVMP gene was cloned and its nucleotide and coded amino acid sequences determined. BVMP consists of 547 amino acid residues, with the zinc-binding sites conserved in common metalloproteases. It shares 57% amino acid identity with thermolysin originating from Bacillus thermoproteolyticus. The three-dimensional structure of BVMP was deduced by computer-aided modeling with the use of the known three-dimensional thermolysin structure as a template. Like thermolysin, BVMP cleaved the oxidized insulin B-chain at the peptide bonds involving the N-terminal sides of hydrophobic and aromatic amino acids. BVMP also showed high hydrolytic activity toward gelatin, collagen, casein, and elastin, especially toward the skeletal proteins at increased NaCl concentration. The high activity was found to be due to enhanced affinity to the substrates. Kinetical data on BVMP indicated that the Km values for the hydrolysis of Cbz-GPGGPA as a collagen model decreased as the concentration of added NaCl increased. Some contribution of this enzyme during the aging of fish sauces at high salt concentrations can thus be expected.
( 2009 )
Discovery of marine Bacillus species by 16S rRNA and rpoB comparisons and their usefulness for species identification.
PMID : 19166882 : DOI : 10.1016/j.mimet.2009.01.003
Systematic studies of the Bacillus group have been biased towards terrestrial and pathogenic isolates, and relatively few studies have examined Bacillus species from marine environments. Here we took twenty Bacillus strains from diverse marine environments and sequenced their 16S rRNA. Using molecular comparisons, we separated the strains into thirteen Bacillus genotypes and identified 9 species: B. aquaemaris. B. badius, B. cereus group, B. firmus, B. halmapalus, B. hwajinpoensis, B. litoralis, B. sporothermodurans, B. vietnamensis, and three indistinguishable Bacilli. In addition, we sequenced the DNA-directed RNA polymerase beta subunit (rpoB) gene and assessed its discriminative power in identifying Bacilli. Phylogenetic trees of Bacillus rpoB genes separated each Bacillus according to their taxonomic positions and were supported statistically. The resolution of Bacillus on the rpoB phylogenetic tree was approximately 4.5 times greater than on the 16S rRNA phylogenetic tree. These results demonstrate that the polymorphism of the Bacillus rpoB gene can be used to identify Bacillus species, providing an improved identification scheme for Bacillus species.
( 2008 )
Bacillus coahuilensis sp. nov., a moderately halophilic species from a desiccation lagoon in the Cuatro Ci?negas Valley in Coahuila, Mexico.
PMID : 18398195 : DOI : 10.1099/ijs.0.64959-0
A moderately halophilic, Gram-positive and rod-shaped bacterium, strain m4-4T, was isolated from a Chihuahuan desert lagoon in Cuatro Ci?negas, Coahuila, Mexico. Strain m4-4T was found to grow optimally at 30-37 degrees C, pH 7.0-8.0 and 5 % NaCl and to tolerate from 0.5 % to 10 % NaCl. It was shown to be aerobic. The genomic DNA G+C content was about 37 mol%. Strain m4-4T exhibited minimal or no growth on most sugars tested. Its major cellular fatty acids were C14 : 0, C16 : 0 and C18 : 1. Based on phylogenetic analysis of 16S rRNA and recA gene sequences, we observed that the closest relatives of the isolate are moderately halophilic Bacillus species, with 16S rRNA gene sequence similarity ranging from 96.6 to 97.4 % (Bacillus marisflavi, Bacillus aquimaris and Bacillus vietnamensis). Additionally, using genomic data it was determined that the type strain contains a total of nine rRNA operons with three slightly different sequences. On the basis of phenotypic and molecular properties, strain m4-4T represents a novel species within the genus Bacillus, for which the name Bacillus coahuilensis sp. nov. is proposed, with the type strain m4-4T (=NRRL B-41737T =CECT 7197T).