ACETYLENE DEGRADATION BY NEW ISOLATES OF AEROBIC-BACTERIA AND COMPARISON OF ACETYLENE HYDRATASE ENZYMES

Aerobic acetylene-degrading bacteria were isolated from soil samples. Two isolates were assigned to the species Rhodococcus opacus, two othe rs to Rhodococcus ruber and Gordona sp. They were compared with known strains of aerobic acetylene-, cyanide-, or nitrile-utilizing bacteria . The acetylene hydratases of R. opacus could be measured in cell-free extracts only in the presence of a strong reductant like titanium(III ) citrate. Expression of these enzymes was molybdenum-dependent. Acety lene hydratases in cell-free extracts of R. ruber and Gordona spp. did not require addition of reductants. No cross-reactivity could be foun d between cell-free extracts of any of these aerobic isolates and anti bodies raised against the acetylene hydratase of the strictly anaerobi c fermenting bacterium Pelobacter acetylenicus. These results show tha t acetylene hydratases biochemically heterogeneous group of enzymes.