Enzymatic activity of marine methanotrophs and its potential use in bioremediation

Methanotrophs are microorganisms with an important role in the biogeochemistry of methane in the ocean. The most important enzyme involved in methane catabolism is the soluble methane monooxygenase (sMMO), being also active on polycyclic aromatic compounds and other oil-derived substances considered pollutants. Sediment samples were incubated in a specific liquid nitrate mineral salt (NMS) medium and in presence of methane as a unique source of carbon to determine sMMO activity of the methanotrophs. Samples were obtained from an area with a visible emanation of methane (Mocha Island) and two areas without emanation (Coronel Bay and Gulf of Arauco). The microorganisms present in the incubations of surface sediments from Mocha Island have a two-fold sMMO activity than the activities obtained in cultures performed under the same conditions but using samples collected from areas without emanation. Moreover, an opposite relationship between sMMO activity and methane concentration was detected in the sediment column, suggesting a positive effect of methane emission on sMMO activity of the methanotroph community of Mocha Island. Considering an area of impact of methane emission in Mocha Island of 400 m(2), the maximun potential sMMO activity could daily transform ca. 43 Kg of naphthalene, thus providing basis for the development of technologies for microbial detoxification of polycyclic aromatic molecules.