Comparative genome analysis of Lysinibacillus sp. B1-CDA, an arsenic resistant bacterium

In this study, we isolated an arsenic resistant bacterium Lysinibacillus sphaericus B1-CDA from arsenic contaminated cultivated land in Bangladesh. L. sphaericus B1-CDA is a naturally occurring soil borne, Gram-positive, rod-shaped bacterium. We have investigated its genetic composition and evolutionary history by massively parallel sequencing and comparative analysis with other Lysinibacillus genomes. Assembly of the sequencing reads produced a draft assembly of the L. sphaericus B1-CDA genome that was ~4.5 Mb in size and covered ~80% of the chromosome. Similar to other Lysinibacillus genomes that have been studied to date, we found that this genome contains abundant regions of similarity with other bacterial genomes. Comparative analysis of L. sphaericus B1-CDA with other Lysinibacillus strains revealed extensive genome rearrangements that may have been facilitated by phages, contributing to horizontal gene transfers that led to species-specific adaptation to different eukaryotic hosts. We also annotated all genes in L. sphaericus B1-CDA predicted to be involved in arsenic resistance. The findings in this study highlighted the significance of arsenic resistance genes to remove arsenic from the contaminated sources. Furthermore, the comparative genome analysis has improved our understanding of genome evolution in bacteria.