不同底物下瘤胃真菌发酵特性及对粗料的附着

Attachment on Rice Straw and Fermentation Profiles of Different Substrates by Rumen Fungi in vitro

采用体外法研究了不同精粗比底物下(A组为全粗料,B组3∶7,C组5∶5,D组7∶3,E组为全精料)瘤胃真菌发酵特性及其对粗饲料(稻草秸)的附着情况。发酵试验结果表明:随底物精料比例的增加,同一时间点真菌数量呈上升趋势,A组到E组发酵96 h的累计产气量显著上升,分别为177.2 mL、198.2 mL、217.4 mL2、33.4 mL和251.5 mL,提示底物中精料比例的增加能促进瘤胃真菌的生长和发酵。此外,随底物精料比例的增加,羧甲基纤维素酶和α-淀粉酶酶活呈上升趋势,木聚糖酶酶活则呈下降趋势。稻草秸附着结果表明:不同发酵时期底物精粗比对附着于稻草秸的瘤胃真菌数量有很大影响。发酵前期(24 h),精料组(B组、C组和D组)附着于稻草秸表面的真菌孢子囊数显著高于粗料组(A组)。发酵后期(72 h),A组和B组附着于稻草秸表面和切缘的孢子囊数高于C组和D组,A组和B组附着于稻草秸表面和切缘的孢子囊数与48 h相比无显著变化,而C组和D组附着于稻草秸表面和切缘的孢子囊数显著下降。这种附着差异可能与不同精粗比底物提供的能量和附着位点不同有关。

In vitro fermentation techniques were used to investigate the attachment on rice straw and fermentation profiles of different concentrate to crude ratio substrates by rumen fungi. The concentration to crude ratio in treatment A to E was all rice straw,3 ： 7,5 ： 5,7： 3 and all corn,respectively. As the fermentation proceeded, the anaerobic fungal population density in the cultures increased with the increasing of concentration to crude ratio, with the largest populations occurring at 48 h. After 96 h of fermentation, cumulative gas production of treatment A to E （177.2 mL, 198. 2 mL, 217.4 mL, 233.4 mL and 251.5 mL,respectively） increased significantly. Those indicated that the increasing of concentration to crude ratio could promote fungi growth and fermentation. CMCase and α-amylase activity tend to increase,while xylanase activity tend to decline with the increasing of concentration to crude ratio. Microscopic studies revealed that the number of sporangia attached to rice straw was influenced greatly by concentration to crude ratio of substrates at different fermentation periods. The number of sporangia attached to surfaces of rice straw at treatment B, C and D were higher significantly than treatment A during the initial fermentation periods. After 72 h of incubation, the number of sporangia attached to surfaces and cut edge of rice straw at treatment A and B were higher than treatment C and D , sporangia attached to surface and cut edge of rice straw kept stable in treatment A and B,but declined sharply in treatment C and D. The exact mechanism is not clear,but it may relate to the difference of energy and attachment sites provide by different concentration to crude ratio substrates.