DNA sequence homology analysis ofars genes in arsenic-resistant bacteria

Homology ofars (arsenic-resistance system) genes was examined among the indigenous bacteria isolated from the soils and sediments of two abandened Au mines, which are highly contaminated with arsenic. The DNA and amino acid sequence homology of thears determinants were investigated using anars genotype. The isolated showed As(III)-oxidation ability containedarsAB genes encoding the efflux pump as well asarsR andarsD regulator genes. ThearsR andarsD leader gene are required for an arsenic resistance system when the high-homology genes (arsR; pl258 52.09% andarsD;Shewanell sp. 42.33%) are controlled by thears inducer-independent regulatory amino acid sequence. These leader gene were observed under weak acidic conditions in the Myoung-bong (pH; 5.0 to 6.0) and Duck-um (pH; 4.0 to 7.0) mines In addition, the strains with the ability of As (V)-reduction involved thearsC gene homologues, as in the strain CW-16 (Pseudomonas putida). The arsenic-resistance genes in the isolated indigenous bacteria showed varying degrees of amino acid similarity to the homologous genes found in the database (GenBank) such asP. putida KT2440: 39–53% forarsR, 22–42% forarsD, 16–84% forarsA, 26–45% forarsB, 17–44% forarsAB, 37–41% forarsC, and 14–47% forarsH. These findings suggested that the function of the variousars gene in indigenous bacteria existing in weakly oxidative conditions may be the key factor for redox mechanisms and biogeochemical systems in arsenic contaminated soils.