不同浓度理中汤多糖作为碳源对肠道拟杆菌及厚壁菌体外生长的影响

Effects of different concentrations of Lizhong decoction polysaccharide as carbon source on in vitro growth of intestinal Bacteroides and Firmicutes

目的观察不同浓度理中汤多糖作为碳源对肠道拟杆菌及厚壁菌体外生长的影响。方法提取高纯度理中汤总多糖。将两株典型肠道拟杆菌(多形拟杆菌ATCC29148和脆弱拟杆菌ATCC25285)及两株厚壁菌(梭菌C6和艰难梭菌SH186)分别分为多糖组、葡萄糖组、BHI组。多糖组中多形拟杆菌分别以含1%、5%、10%、20%、30%、40%的理中汤多糖培养基培养,脆弱拟杆菌分别以含1%、5%、10%、20%、30%、40%、50%、60%的理中汤多糖培养基培养;葡萄糖组以含葡萄糖的培养基培养;BHI组以含BHI的培养基培养。用连续取样和分光光度法测定OD值,再折算成细菌生长的浓度进行分析。结果对于两株拟杆菌,最优多糖组细菌浓度最大值均高于BHI组,BHI组高于葡萄糖组,其中30%浓度多糖组的多形拟杆菌浓度最高,50%浓度多糖组的脆弱拟杆菌浓度最高(P均<0.05)。对于两组厚壁菌,BHI组的梭菌浓度高于多糖组和葡萄糖组;仅BHI组的艰难梭菌有生长,而葡萄糖组和多糖组的艰难梭菌未见生长。结论不同浓度的理中汤多糖均能影响典型拟杆菌的体外生长,相对于BHI和葡萄糖碳源的影响,理中汤多糖是一种适合拟杆菌生长的优势碳源,对于多形拟杆菌和脆弱拟杆菌体外生长的最优浓度分别为30%和50%;但理中汤多糖对厚壁菌的生长促进作用不明显,甚至有抑制作用。

Objective To observe the effects of different concentrations of Lizhong decoction polysaccharide as carbon source on the in vitro growth of intestinal Bacteroides and Firmicutes. Methods The total polysaccharide with high purity was extracted from Lizhong decoction. Two typical intestinal Bacteroidetes（ Bacteroides thetaiotaomicron ATCC 29148 and Bacteroides fragile ATCC25285） and two Firmicutes（ Costridium C6 and Clostridium difficile SH186） were cultured in different media with different carbon source including Lizhong decoction polysaccharide,glucose and brian heart infusion（ BHI）,respectively. For Lizhong decoction polysaccharide group,Bacteroides thetaiotaomicron was cultured in the medium containing different concentrations of 1%,5%,10%,20%,30% and 40% Lizhong decoction polysaccharide,while Bacteroides fragillis was cultured in the medium containing different concentrations of 1%,5%,10%,20%,30%,40%,50% and 60% Lizhong decoction polysaccharide,respectively; the glucose group and BHI group were cultured in the media containing glucose and BHI,respectively. The bacterial optical density（ OD） values were determined by continuous sampling and spectrophotometry,and then were converted to the bacterial growth concentration for further analysis.Results For the two strains of Bacteroides,the maximum bacterial concentration of the optimal Lizhong decoction polysaccharide group was higher than that in BHI group,and the BHI group was higher than the glucose group; as for Bacteroides thetaiotaomicron,the optimal concentration of Lizhong decoction polysaccharide group was 30% while that of Bacteroides fragile was 50%（ P〈0. 05）. For the two strains of Firmicutes,the maximum bacterial concentration in the BHI group was higher than those in the polysaccharide group and glucose group,respectively. Meanwhile,the Clostridium difficile only grew in the BHI group, while in the glucose group and polysaccharide group, Clostridium difficile did not grow.Conclusions Lizhong decoction polysaccharides at different concentrations can affect the growth of typical Bacteroidetes in vitro. Compared with the BHI and glucose as the carbon sources,Lizhong decoction polysaccharide is a potential favorable carbon source for the in vitro growth of Bacteroidetes,and the optimum concentrations for in vitro growth of Bacteroides thetaiotaomicron and Bacteroides fragile are 30% and 50%,respectively,while Lizhong decoction polysaccharide has no obvious or inhibitory effect on the growth of Firmicutes.