双酶梭菌TK6的筛选及益生物质对其代谢活力的影响

Screening Clostridium bifermentans Strain TK6 and the Effect of Prebiotics on its Metabolic Activity

本实验采用倾注法从健康成年人的粪便中筛选双酶梭菌(Clostridium bifermentans)TK6,该菌有益于反刍动物,其发酵产物有消化酶、短链脂肪酸以及α–酮异己酸(KIC)等益生物质.分别利用7种低聚糖(低聚葡萄糖、低聚果糖、低聚半乳糖、低聚木糖、低聚异麦芽糖、棉籽糖以及水苏糖)为唯一碳源进行TK6的对比发酵,测定其不同发酵液中短链脂肪酸、异丁酸、α–酮异己酸、消化酶等益生物质的含量.实验结果表明:不同低聚糖作为唯一碳源对TK6的生长促进程度不同,并对其产生的水解酶、短链脂肪酸等物质有不同的影响.菌株TK6利用低聚异麦芽糖为唯一碳源时,其活菌数最大,为(7.97±0.16)×10~8,m L^(–1);并且其产乙酸、丁酸的促进作用最大,分别为(65.70±0.37)mmol/L和(53.51±0.52)mmol/L;产纤维素酶活力最高,达到(1,994.84±254.52)U/m L.菌株利用低聚木聚糖为唯一碳源时,其发酵液产木聚糖酶的酶活力最高,为(135.86±1.82)U/m L;利用低聚果糖为唯一碳源时,其发酵液蛋白酶活力最高,为(10.12±4.34)U/m L.当添加150,mmol/L的L–亮氨酸,37,℃孵化4,h时,KIC产量最高为(8.18±0.06)mg/L.

Clostridium bifermentans TK6(C.bifermentansTK6)is a prebiotic of ruminant,whose fermentation products contain digestive enzyme,short chain fatty acid(SCFA)andα-ketoisocaproate(KIC).It was screened from feces of healthy adults with the overlay method.Seven functional oligosaccharides,glucoseoligosaccharides(GLOS),fructooligosaccharides (FOS),galactooligosaccharides(GOS),xylooligosaccharides(XOS),isomaltoolig-osaccharides(IMOS),raffinose and stachyose,as the sole carbon source,were fermented respectively byC.bifermentansTK6 and contrasted. And then,the prebiotic content of each fermention product including SCFA,isobutyrate,KIC and hydrolase was checked.The results showed that each type of oligosaccharides as a sole carbon source has different effects on the growth of TK6 and the yield of hydrolase and SCFA.There is a significant increase of TK6 in IMOS,and the viable count is(7.97±0.16)×108 mL–1.The production of acetate and butyrate reached(65.70±0.37)mmol/L and(53.51±0.52)mmol/L,respectively.Moreover,the cellulase activity reached(1,994.84±254.52)U/mL.Fermentation of XOS by TK6 resulted in the highest xylanase activ-ity(135.86±1.82)U/mL,and the highest protease activity using FOS was(10.12±4.34)U/mL.The highest production of KIC was(8.18±0.06)mg/L while adding 150 mmol/LL-leucine and hatched 4 h at 37℃.