Metabolism of chlorinated methanes,ethanes, and ethylenes by a mixed bacterial culture growing on methane

Summary Soil was taken from the top 10 cm of a soil column that removed halogenated aliphatic hydrocarbons in the presence of natural gas. This soil was used as an enrichment inoculum to determine that the removals seen in the soil column were in fact of a microbiological nature. Methane served as the source of carbon and energy and was consumed immediately by the enrichments. After several transfers of the enrichments, a stable consortium of at least three bacterial types was obtained. The predominant bacterium was a non-motile, gram-negative coccus. This stable consortium was able to remove chlorinated methanes, ethanes, and ethylenes when grown with methane and oxygen in the headspace. Methane was required for the removals to be observed. Acetylene inhibited the removals, which further suggests the involvement of methanotrophs. Benzene and toluene were removed by the mixed culture with or without methane in the headspace. Fatty acid analysis of the mixed culture resulted in a profile that indicated that the predominant organism was a type II methanotroph. This study provides further evidence that methanotrophic bacteria are capable of cometabolizing a wide range of chlorinated methanes, ethanes, and ethylenes.