Whole Genome Sequencing and Comparative Genomic Analyses of LZH-9, a Halotolerant Strain with Excellent COD Removal Capability.

Halotolerant microorganisms are promising in bio-treatment of hypersaline industrial wastewater. Four halotolerant bacteria strains were isolated from wastewater treatment plant, of which a strain LZH-9 could grow in the presence of up to 14% (/) NaCl, and it removed 81.9% chemical oxygen demand (COD) at 96 h after optimization. Whole genome sequencing of LZH-9 and comparative genomic analysis revealed metabolic versatility of different species of , and abundant genes involved in xenobiotics biodegradation, resistance to toxic compound, and salinity were found in all tested species of , in which Horizontal Gene Transfer (HGT) contributed to the acquisition of many important properties of spp. such as toxic compound resistance and osmotic stress resistance as revealed by phylogenetic analyses. Besides, genome wide positive selection analyses revealed seven genes that contained adaptive mutations in spp., most of which were multifunctional. Further expression assessment with Codon Adaption Index (CAI) also reflected the high metabolic rate of to digest potential carbon or nitrogen sources in organic contaminants, which was closely linked with efficient COD removal ability of strain LZH-9. The high COD removal efficiency and halotolerance as well as genomic evidences suggested that LZH-9 was promising in treating hypersaline industrial wastewater.