Study on Arsenic Methyltransferase of Cellulomonas sp. K31 Expressed in Recombinant E. coli

This study aimed to facilitate efficient arsenic detoxification by inducing the microbial methylation of inorganic arsenic. Recombinant Escherichia coli strains K31 was transformed to overexpress arsenic methyltransferase, and the methylation of inorganic arsenic was evaluated using the enzyme extracted from the strain. To ensure continuous reactions by maintaining enzymatic activity, the extracted enzyme was immobilized in microcapsules (MC) to catalyze the methylation of inorganic arsenic. The total yield of methylated organic arsenic compounds in strain K31 was 57.0% (after 2 h of incubation at pH 6.5 and 40°C), of which trimethyl arsenic compounds (TMAC) accounted for 17.9%. When arsenic was methylated using MC prepared with the crude enzyme solution, the total yield of methylated organic arsenic compounds was 15.6%. The residual enzymatic activity was calculated to be 55.8%. Future studies should aim to increase the efficiency of conversion to TMAC, thus elevating the yield of organic arsenic compounds, by optimizing the conditions for enzyme immobilization in MC.