Isolation, identification and fibrolytic characteristics of rumen fungi grown with indigenous methanogen from yaks (Bos grunniens) grazing on the Qinghai-Tibetan Plateau.

Abstract

To obtain co-cultures of anaerobic fungi and their indigenously associated methanogens from the rumen of yaks grazing on the Qinghai-Tibetan Plateau and investigate their morphology features and ability to degrade lignocellulose. Twenty fungus-methanogen co-cultures were obtained by Hungate roll-tube technique. The fungi were identified as Orpinomyces, Neocallimastix and Piromyces genera based on the morphological characteristics and internal transcribed spacer 1 sequences analysis. All methanogens were identified as Methanobrevibacter sp. by 16S rRNA gene sequencing. There were four types of co-cultures: Neocallimastix with Methanobrevibacter ruminantium, Orpinomyces with M.ruminantium, Orpinomyces with Methanobrevibacter millerae and Piromyces with M.ruminantium among 20 co-cultures. In vitro studies with wheat straw as substrate showed that the Neocallimastix with M.ruminantium co-cultures and Piromyces with M.ruminantium co-cultures exhibited higher xylanase, filter paper cellulase (FPase), ferulic acid esterase, acetyl esterase activities, invitro dry matter digestibility, gas, CH4 , acetate production, ferulic acid and p-coumaric acid releases. The Neocallimastix frontalis Yak16 with M.ruminantium co-culture presented the strongest lignocellulose degradation ability among 20 co-cultures. Twenty fungus-methanogen co-cultures were obtained from the rumen of grazing yaks. The N.frontalis with M.ruminantium co-cultures were highly effective combination for developing a fermentative system that bioconverts lignocellulose to high activity fibre-degrading enzyme, CH4 and acetate. The N.frontalis with M.ruminantium co-cultures from yaks grazing on the Qinghai-Tibetan Plateau present great potential in lignocellulose biodegradation industry.