Methanotrophic Community Detected by DNA-SIP at Bertioga’s Mangrove Area, Southeast Brazil

Abstract

Methanotrophic bacteria can use methane as sole carbon and energy source. Its importance in the environment is related to the mitigation of methane emissions from soil and water to the atmosphere. Brazilian mangroves are highly productive, have potential to methane production, and it is inferred that methanotrophic community is of great importance for this ecosystem. The scope of this study was to investigate the functional and taxonomic diversity of methanotrophic bacteria present in the anthropogenic impacted sediments from Bertioga mangrove (SP, Brazil). Sediment sample was cultivated with methane and the microbiota actively involved in methane oxidation was identified by DNA-based stable isotope probing (DNA-SIP) using methane as a labeled substrate. After 4 days of incubation and consumption of 0.7 mmol of methane, the most active microorganisms were related to methanotrophs Methylomonas and Methylobacter as well as to methylotrophic Methylotenera, indicating a possible association of these bacterial groups within a methane derived food chain in the Bertioga mangrove. The abundance of genera Methylomonas, able to couple methane oxidation to nitrate reduction, may indicate that under low dissolved oxygen tensions some aerobic methanotrophs could shift to intraerobic methane oxidation to avoid oxygen starvation.