Molecular identification of rumen methanogens: Technologies, advances and prospects

Abstract

Methanogenesis provides a means of H2 disposal and a mechanism to maintain low partial H2 pressure in the rumen, a prerequisite for efficient ruminal fermentation. As methanogens possess stringent requirements for cultivation, only a few species have been successfully isolated from the rumen and cultured. Culture independent molecular based approaches have provided new insight into the diversity, prevalence and role of methanogens within the overall rumen microbial community. In addition, recent developments in next generation sequencing technology have enabled the ruminal microbial community to be investigated at a metagenomic level, providing information to explore the structure, function and metabolic diversity of microbial communities. This review summarizes existing molecular technologies utilized in studies of ruminal methanogens by outlining their advantages and limitations, and introduces future applications of next generation sequencing approaches for studying the ecology of ruminal methanogens. These approaches could provide new understanding of the mechanisms of methanogenesis, as well as interactions of methanogens with other members of the rumen microbial community. An understanding of the fundamental role of methanogens in ruminal CH4 production would provide insight into methods of curtailing emissions of this greenhouse gas from ruminants.This article is part of the special issue entitled: Greenhouse Gases in Animal Agriculture – Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors; K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson.