梅山与长白母猪粪样微生物体外发酵八种纤维底物的特性比较

A comparison of in vitro fermentation characteristics of eight fiber substrates by faecal microbiota from Meishan and Landrace sows

本研究旨在比较不同品种母猪(梅山猪与长白猪)粪样中微生物对不同纤维底物的体外降解能力,同时分析粪样中的主要纤维降解菌数量。采集梅山(n=5)和长白(n=5)母猪新鲜粪样作为发酵接种物,以果胶、纤维素、菊粉、麦壳、麸皮、木聚糖、玉米芯渣及苜蓿作为纤维底物进行体外发酵,测定产气量和发酵液挥发性脂肪酸(vola-tile fatty acid,VFA)浓度。粪样同时用于提取细菌总核酸,变性梯度凝胶电泳(denaturing gradient gel electrophoresis,DGGE)和real-time PCR对菌群区系进行分析。体外发酵结果表明,从发酵后9 h至96 h结束,长白猪接种物各组的累积产气量、有机物校正产气量分别显著(P<0.05)和极显著(P<0.01)高于梅山猪,长白猪T1/2和Tmax显著低于梅山猪(P<0.05),且发酵终产物中乙酸和总VFA浓度显著高于梅山猪接种物(P<0.05),整个发酵过程中不同底物间累积产气量差异显著(P<0.05),累积产气量从高到低的组别依次为:菊粉>麸皮>果胶>苜蓿>麦壳>玉米芯渣>木聚糖>纤维素。DGGE分析表明,梅山与长白母猪粪样菌群图谱中存在许多共同条带。Real-time PCR定量分析表明,梅山母猪粪样中的总细菌的16S rRNA基因拷贝数显著高于长白母猪(P<0.05),而拟杆菌、产琥珀酸丝状杆菌、黄化瘤胃球菌和白化瘤胃球菌等纤维降解菌数量及其占总菌比例差异均不显著(P>0.05)。结果显示,尽管2个品种母猪粪样中纤维降解菌数量无显著差异,但是长白母猪粪样微生物体外发酵纤维底物的能力高于梅山母猪。

In vitro fermentation characteristics of different fiber substrates by faecal microbiota and fiber-degrading baceria in faeces from Meishan and Landrace sows were compared. Fresh faeces from Meishan and Landrace sows were collected and used as inoculum in an in vitro fermentation test. Eight different substrates, （pectin, cellulose, xylan, inilin, wheat hul, wheat bran, maize pulp, and alfalfa） were used in the test. After 96 h fermentation, gas production was recorded, and gas samples collected to determine VFA concentrations. Total bacterial DNA was extracted and used for DGGE and real-time PCR to analyse microbiota composition and the main fiber-degrading bacteria. Cumulative gas production, concentration of acetate and of total VFAs were significantly higher （P〈0.05） when the faeces from Landrace sows were used as inoculum as compared with those from Meishan sows. There was no significant （P〉0.05） difference in the concentrations of propionate and butyrate between the two breeds. T1/2 and Tmax were significantly lower （P〈0.05） in Landrace sows than in Meishan sows. The order of degradability of all substrates was： inulin〉wheat bran〉pectin〉alfafa〉wheat hull〉maize pulp〉xylan〉cellulose. DGGE anlysis of total bacterial communities showed that there were no pig breed specific bands in the profiles from the faeces of the two breeds. Real-time PCR analysis showed that the 16S rRNA gene copies of total bacteria in faeces of Meishan sows were significantly （P%0.05） higher than those in Landrace sows, while there was no significant （P〉0.05） difference in the 16S rRNA gene copies of Bacteroidetes, Fibrobacter succinogenes, Ruminococcus flavefaciens and Ruminococcus albus and their proportions within the total bacterial population. Although there was no significant difference in the numbers of main fiber-degrading bacteria between Meishan and Landrace sows, the Landrace sows may have a stronger ability to degrade fiber as compared to Meishan sows.