4种山药多糖的体外发酵特性比较研究

Comparative Study on in vitro Fermentation Characteristics of Four Fractions of Chinese Yam Polysaccharides

采用体外发酵技术评价分段醇沉得到的4个山药多糖对宁乡猪盲肠食糜体外发酵特性和发酵产物的影响,探讨其用作动物功能性营养调控剂的可行性。乙醇终浓度(%)分别为30、45、60和75时沉淀得到4个山药多糖,用硫酸蒽酮法测得其总多糖含量(%)分别为45.85、56.24、90.91和13.87。选用正常饲喂的肥育宁乡猪,处死后无菌取盲肠食糜作为接种物,分别以4个山药多糖和葡萄糖为底物进行体外发酵。于不同发酵时间点记录产气量,48h后检测发酵液pH值、NH3和SCFA含量。结果表明,75%醇沉多糖发酵动力学参数最优,并极显著优于葡萄糖组(P<0.01);45%、60%醇沉多糖和葡萄糖组pH值最低,60%、75%醇沉多糖和葡萄糖组的NH3含量最低;葡萄糖组的乙酸、丁酸和异丁酸含量均显著高于其它处理组(P<0.05),60%醇沉多糖组的丙酸含量稍高于、丁酸和异丁酸含量略低于其它3个多糖组。丁酸和异丁酸含量与pH值和NH3含量呈显著相关。提示60%和75%醇沉山药多糖是2种理想的可被宁乡猪盲肠微生物利用的碳源,并可改变微生物产生的SCFA含量与组成。

The present study was conducted to determine the fermentation characteristics of four fractions of Chinese yam polysaecharides （CYPF） in vitro by evaluating the difference of fermentation kinetic parameters and fermentation producfions among different CYPFs in order to investigate the possibility of CYPFs as functional dietary additives used in domestic animals and poultry. CYPF1, CYPF2, CYPF3 and CYPF4 were extracted from the Chinese yam with water-extracting-ethanol-precipitation method,when the end concentrations of the ethanol were 30% ,45% , 60% and 75%, respectively. Their contents （ % ） assayed by vitriol-anthracene ketone were 45.85,56.24,90.91 and 13.87 ,respectively. Cecal digesta collected from Ningxiang pig fed on normal diet was used as the inoeulums and the four polysaccharides were used as the substrates during the in vitro fermentation. The slurry was fermented for 48 h in an anaerobic in vitro system, and then the fermentation kinetic parameters, pH value, NH3 content, production and composition of short-chain fatty aeids in the fermentation broth were determined. Our data showed that the maximum volume and rate of gas production in CYPF2-, CYPF3-and CYPF4-supplemented groups were higher （ P 〈 0.05 ） than the CYPF2-or glucose-supple- mented groups and free-supplemented group,while the lag time of gas production, pH value and NH3 content were lower than the CYPF2-or free-supplemented group. Contents of acetic acid,isobutyric acld and butanoic acid in the four polysaccharides-supplemented groups were lower （ P 〈 0.05 ） than the glucose-supplemented group, while of acetic acid and butanoic acid were higher （ P 〈 0. 05） than the free-supplemented group. Contents of propionic acid in the CYPFI-, CYPF2-and CYPF3-supplemented groups were higher （P 〈 0.05） than the free-supplemented group. In addition, the contents of butyric acid and isobutyric acid had correlation （P 〈 0.05 ） with pH value and NH3 content. Collectively, CYPF3 and CYPF4 may be good sources of carbon and energy, and therefore modulate SCFA production patterns in hindgut of the Ningxiang pigs.