直肠菌群对两种不溶性膳食纤维的体外发酵

目的探究不溶性膳食纤维在肠道中被发酵利用的规律。方法以直肠菌群为研究对象,以去淀粉麦麸和甘蔗渣分别作为底物,在厌氧条件下进行体外发酵,分别在发酵0、4、8、12和24h取样,测pH、运用选择性平板计数、气相色谱测短链脂肪酸含量。结果以去淀粉麦麸和甘蔗渣为底物的发酵培养基在发酵24h后,pH分别降到了5.35和5.43;双歧杆菌属、乳杆菌属、肠球菌属、肠杆菌属、拟杆菌属以及总厌氧菌的数量在两种底物的培养条件下不同的时间段数量变化均不显著;去淀粉麦麸和甘蔗渣两种底物均能被肠道菌群利用产生短链脂肪酸,其中在发酵24h后丙酸含量最多,且分别为0.58和0.56mg/ml;乳酸在发酵过程中被积累并能被一些肠道菌利用而消耗减少。结论不溶性膳食纤维能被肠道菌群利用,并且在发酵过程中可能有不同菌属的生长演替。

Fermentation of two insoluble dietary fibers by colonic microflora in vitro

Objective To investigate the rule of insoluble dietary fiber fermentation in intestinal tract.Methods Using destarched wheat bran and sugarcane residue as substrates for the fermentation of colonic microflora in vitro in anaerobic conditions.Samples were collected at 0,4,8,12 and 24 h after fermentation,and the pH value,selective plate colony counts were measured and the content of SCFAs were detected with GC.Results After fermenting for 24 hours in vitro,the pH value of destarched wheat bran and sugarcane residue culture decreased to pH 5.35 and pH 5.43.The change of colony counts of Bifidobacterium,Lactobacillus,Enterococci,Enterobacter,Bacteroides and total anaerobic bacterium was not significant in two media with different substrates at different fermentation periods.Both destarched wheat bran and sugarcane residue could be utilized by colon microbials to produce SCFAs,most of which was propionate at the amount of 0.58mg/ml and 0.56mg /ml respectively.During the fermentation process,lactic acid was accumulated and promptly consumed by colonic microflora.Conclusion Insoluble dietary fiber could be fermented by intestinal microflora.The growth succession of colonic microflora might be varied during fermentation.