Construction of a genetically engineered microorganism with high tolerance to arsenite and strong arsenite oxidative ability

Genetically engineered microorganisms (GEMs) have shown great potential for use in environmental bioremediation. In this study, the TTHB128 and TTHB127 genes, which encode the small and large subunits of arsentie oxidase in Thermus thermophilus HB8, respectively, were cloned into the broad-host-range vector pBBR1MCS-5 to produce the recombinant plasmid, TTHB127-pBBR1MCS-5-TTHB128. This resulted in successful construction of a GEM with high tolerance to arsenite and strong arsenite oxidative ability. Culture of the GEM in media containing arsenite for 28 h resulted in 87.6% of the arsenite being oxidized. Overall, the oxidative ability of the GEM was much stronger than that of the wild type host strain. Gentamicin was necessary to maintain the stability of the recombinant plasmid, TTHB127-pBBR1MCS-5-TTHB128, in the GEM. The oxidative ability of the GEM remained unchanged when it was grown in medium containing gentamicin (60 mg/L) for 30 growth cycles, after which its activity gradually decreased.