Genomic characterization of a dehalogenase-producing bacterium (Bacillus megaterium H2) isolated from hypersaline Lake Tuz (Turkey)

Abstract

Pollution of the environment by organohalide compounds is a worldwide issue. Organohalide-degrading microbes isolated from such contaminated environments or extreme habitats could be key agents for the bioremediation of pollutants. We previously identified this bacterium as Bacillus thuringiensis H2 based on biochemical and 16S rRNA analysis. However, this bacterium was found to be related to Bacillus megaterium species by current full genome sequence method. Herein, we report the complete genome sequence of Bacillus thuringiensis H2 with a 6,412,227 bp genome size, having 18 putative circular plasmids and 6962 protein-coding genes. Genome analysis revealed nine organohalide degradation-related enzymes. Three 2-haloalkanoic acid dehalogenases (EC 3.8.1.2) and six haloacid dehalogenase-like (HAD) enzymes of the hydrolase family alongside other pollutant-degrading enzymes were also present. The predicted DehH2 dehalogenase enzyme-encoding genes were discovered alongside nine other enzymes. Genome annotation analysis also revealed that the degradation genes are regulated by separate regulatory proteins both in chromosome and plasmids (plasmid 2 and 9), which could be responsible for regulating the organohalides degradation. In a nutshell, the findings of this study contribute to the understanding of the function of dehalogenases and related genes for dehalogenase regulation. The data also convey the possible wide application potential of the above bacterium for the bioremediation of organohalide-polluted environments.