The dynamics of microorganism populations and fermentation characters of co-cultures of rumen fungi and cellulolytic bacteria on different substrates
不同精粗比底物下瘤胃真菌和纤维降解细菌共培养发酵特性及菌群变化

In vitro co-culture technique and DGGE were used to investigate the dynamics of microorganism populations and fermentation characters of co-cultures of rumen fungi and cellulolytic bacteria at different substrates (concentrate to crude ratio in treatment A to E was all rice straw, 3:7, 5:5, 7:3 and all corn, respectively). The results showed that, compared with Oh, fungal population density at 24h increased in treatment B and C, but decreased in treatment A and D, and no fungi was detected in treatment E; but cellulolytic bacteria population at 24h increased with the increasing of concentrate to crude ratio. At the end of 48h fermentation, no fungi were detected in all treatments; cellulolytic bacteria population increased from treatment A to treatment C, but decreased from treatment D. DGGE results showed that samples collected in treatment A, B and C had similar DGGE patterns with about 11 dominant bands, but dominant bands in treatment D and E decreased markedly compared to treatments A, B and C. With the increasing of concentrate to crude ratio, pH value of the co-culture decreased dramatically (P < 0.05). During the fermentation periods, acetate was the major VFA in co-culture, the acetate to propionate ratio decreased from treatment A to treatment C, but increased from treatment D. With the increasing of concentrate to crude ratio, the total VFA at 48h increased from treatment A to treatment C, and then decreased. At the end of 48h fermentation, CMCase activity and xylanase activity were highest in treatment A. alpha-Amylase activity increased from treatment A to treatment D, but treatment E was the lowest in all treatments.