Genotypic and phenotypic diversity of <it>Bacillus </it>spp. isolated from steel plant waste

• Main Authors: Chartone-Souza Edmar, Assis Paulo S, Costa Patrícia S, Lima-Bittencourt Cláudia I, Reis Mariana P, Freitas Dulcecleide B, Nascimento Andréa MA
• Format: Article
• Language: English
• Published: BMC 2008-10-01
• Series: BMC Research Notes
• Online Access: http://www.biomedcentral.com/1756-0500/1/92

<p>Abstract</p> <p>Background</p> <p>Molecular studies of <it>Bacillus </it>diversity in various environments have been reported. However, there have been few investigations concerning <it>Bacillus </it>in steel plant environments. In this study, genotypic and phenotypic diversity and phylogenetic relationships among 40 bacterial isolates recovered from steel plant waste were investigated using classical and molecular methods.</p> <p>Results</p> <p>16S rDNA partial sequencing assigned all the isolates to the <it>Bacillus </it>genus, with close genetic relatedness to the <it>Bacillus subtilis </it>and <it>Bacillus cereus </it>groups, and to the species <it>Bacillus sphaericus</it>. tDNA-intergenic spacer length polymorphisms and the 16S–23S intergenic transcribed spacer region failed to identify the isolates at the species level. Genomic diversity was investigated by molecular typing with rep (repetitive sequence) based PCR using the primer sets ERIC2 (enterobacterial repetitive intergenic consensus), (GTG)₅, and BOXAIR. Genotypic fingerprinting of the isolates reflected high intraspecies and interspecies diversity. Clustering of the isolates using ERIC-PCR fingerprinting was similar to that obtained from the 16S rRNA gene phylogenetic tree, indicating the potential of the former technique as a simple and useful tool for examining relationships among unknown <it>Bacillus </it>spp. Physiological, biochemical and heavy metal susceptibility profiles also indicated considerable phenotypic diversity. Among the heavy metal compounds tested Zn, Pb and Cu were least toxic to the bacterial isolates, whereas Ag inhibited all isolates at 0.001 mM.</p> <p>Conclusion</p> <p>Isolates with identical 16S rRNA gene sequences had different genomic fingerprints and differed considerably in their physiological capabilities, so the high levels of phenotypic diversity found in this study are likely to have ecological relevance.</p>