乙酸与丙酸比对体外瘤胃液挥发性脂肪酸发酵模式和微生物群体多样性的影响

摘要

本文主要研究乙酸与丙酸比(乙/丙)对体外瘤胃液挥发性脂肪酸发酵模式及微生物群体多样性的影响.试验以4头瘤胃瘘管山羊提供瘤胃液,设4个处理,培养底物乙/丙分别为30:70、50:50、70:30和100:0.测定培养液中挥发性脂肪酸的浓度的变化,并通过单链构象多态性(SSCP)图谱检测细菌和原虫的群体多样性.结果表明:培养液乙酸浓度以100:0组最高,显著高于其他3组(P＜0.05),50:50组最低；丙酸浓度以30:70组最高,显著高于50:50和70:30组(P＜0.05)；丁酸的浓度30:70组显著高于70:30组(P＜0.05)；各组培养液乙/丙均接近3:1,30:70组显著低于70:30和100:0组(P＜0.05).细菌SSCP图谱显示,50:50组条带数最多,100:0组条带数最少；原虫的SSCP图谱以100:0组条带数最多,30:70组条带数最少.细菌、原虫的SSCP图谱皆以50:50和70:30组图谱间相似性指数为高.总之,乙/丙对培养液挥发性脂肪酸模式、细菌或原虫的群体多样性都存在影响.%This paper was conducted to investigate the effects of acetate to propionate ratio on the pattern of volatile fatty acid (VFA) fermentation and diversities of rumen microorganisms. Four goats fitted with permanent ruminal cannulas were used to provide rumen fluid for the in vitro study. The four treatments were set according to the acetate to propionate ratio in culture substrates, which were 30:70, 50:0, 70:30, and 100:0, respectively. Variation of VFA concentration was recorded, and diversities of bacteria and protozoa were investigated by SSCP fingerprint technique. The results showed as follows: acetate concentration of 100:0 group was the highest and was significantly higher than that of the other three groups (P < 0. 05) , while that of 50:50 group was the lowest. Propionate concentration of 30:70 group was the highest and was significantly higher than that of groups 50:50 and 70:30 (P <0. 05). Butyrate concentration of 30:70 group was significantly higher than that of 70:30 group (P <0. 05). Acetate to propionate ratios in culture medium of all the treatments were close to 3:1, while that of 30:70 group was significantly lower than that of groups 70:30 and 100:0 ( P <0.05). Bacterial SSCP fingerprint showed that bands number of 50:50 group was the most, while that of 100:0 group was the least; protozoa SSCP fingerprint showed that bands number of 100:0 group was the most, while that of 30:70 group was the least. Similarity index was the highest between 50:50 group and 70:30 group on both bacteria and protozoa fingerprints. In conclusion, the VFA pattern and diversities of rumen bacterial or protozoal community can be modified by acetate to propionate ratio in vitro.