Abstract

Fumarate reducing bacteria, able to convert fumarate to succinate, are possible to use for the methane reduction in rumen because they can compete for H2 with methanogens. In this, we isolated fumarate reducing bacteria from a rumen of Korean native goat and characterized their molecular properties [fumarate reductase A gene (frdA)], fumarate reductase activities, and productions of volatile fatty acids and gas. Eight fumarate reducing bacteria belonging to Firmicutes were isolated from rumen fluid samples of slaughtered Korean black goats and characterized their phylogenetic positions based on 16S rRNA gene sequences. PCR based analyses showed that only one strain, closely related to Mitsuokella jalaludinii, harbored frdA. The growths of M. jalaludinii and Veillonella parvula strains were tested for different media. Interestingly, M. jalaludinii grew very well in the presence of hydrogen alone, while V. parvula grew well in response of fumarate and fumarate plus hydrogen. M. jalaludinii produced higher levels of lactate (P≤0.05) than did V. parvula. Additionally, M. jalaludinii produced acetate, but not butyrate, whereas V. parvula produced butyrate, not acetate. The fumarate reductase activities of M. jalaludinii and V. parvula were 16.8 ± 0.34 and 16.9 ± 1.21 mmol NADH oxidized/min/mg of cellular N, respectively. In conclusion, this showed that M. jalaludinii can be used as an efficient methane reducing agent in rumen.

• Keywords: fumarate reductase; Mitsuokella jalaludinii; Korean native goat; VFA