A review on microbial aerobic methane oxidation in marine environment

The aerobic oxidation of methane driven by methanotrophs is a key process for methane migration and transformation in marine environment. Its contribution to the degradation of methane should not be ignored because it may effectively reduce methane flux to the atmosphere and affect the carbon cycle in the sea. In this paper, a large number of domestic and foreign literatures are systematically investigated, from which it is found that the aerobic oxidation of methane occurs widely in marine environment. It may even occur in some extreme environments with very high pressure and dynamic migration of methane seepage, such as the deep sea and hydrothermal vents at depths of more than 3 000 m. In these environments, methanotrophs are mainly predominated by the type I of oxidizing bacteria. Meanwhile, the type I and type II of oxidizing bacteria have a certain bias to environmental conditions such as methane and trace metal elements, and the types of oxidizing bacteria are also different in water and sediment. At the same time, temporal and spatial differences occur in the aerobic oxidation intensity of methane, which is significantly affected by such environmental factors as temperature, methane concentration, oxygen concentration and trace metal elements. However, the influence of pressure and methane seepage on aerobic oxidation is not so clear up to date. Further research and exploration are required so as to enrich the knowledge on diversity of methane-oxidizing bacteria and improve the understanding of their physiological and ecological characteristics. In addition, it is a need to carry out detailed research on the aerobic oxidation process under the condition of submarine high-pressure leakage, in order to better understand the oxidation process of the environment. It would be of great significance to the revealing of the mechanism of methane migration and transformation and evaluation of its ecological and environmental effects.