乳杆菌和双歧杆菌对碳水化合物体外利用的比较研究

Comparison of in Vitro Carbohydrate Utilization by Lactobacilli and Bifidobacteria

在含有13种碳水化合物(包括低聚果糖(fructooligosaccharide,FOS)、FOS(Vilof)、低聚木糖、低聚半乳糖、短链菊粉、长链菊粉、低聚异麦芽糖、水苏糖、抗性糊精、聚葡萄糖、L-阿拉伯糖、乳糖醇和赤藓糖醇)作为唯一碳源的纯培养基上,比较12株乳杆菌和6株双歧杆菌的生长情况,记录培养24 h和72 h的OD_(600 nm)和pH值。结果表明:不同碳水化合物对菌株生长的作用有较大差异;培养24 h时,抗性糊精、聚葡萄糖和赤藓糖醇对所有菌株的促生长作用都非常有限,可能是因为这些菌株缺乏相应的酶来水解糖苷键;FOS、低聚木糖、低聚半乳糖、菊粉、水苏糖、L-阿拉伯糖、乳糖醇的促生长作用具有菌株特异性,这可能是因为每个菌株产生的细胞内或细胞外酶的差异;短链菊粉和长链菊粉的发酵特性具有菌株特异性,长链菊粉使嗜酸乳杆菌的发酵更加缓慢,但不适用于其他菌株;不同制造商生产的FOS虽然来源相同,但在发酵过程中表现出差异,这可能是因为杂质含量不同。推测益生元对人体健康有益,其作用不是直接促进体内的乳杆菌或双歧杆菌生长,而是先被肠道中的其他细菌降解,然后被益生菌菌株利用。

The growth of twelve Lactobacillus strains and six Bifidobacterium strains on a medium containing 13 carbohydrates including prebiotics(fructooligosaccharide(FOS),FOS(Vilof),xylooligosaccharide(XOS),galactooligosaccharide(GOS),short-chain inulin,long-chain inulin,isomalto oligosaccharide(IMO),stachyose,resistant dextrin,polydextrose,L-arabinose,lactitol,and erythritol)as sole carbon sources was compared using lactose as a control.Optical density at 600 nm(OD_(600 nm))and pH were recorded after 24 and 72 h of culture.Results showed great differences in the growth of strains on different carbohydrates.Resistant dextrin,polydextrose,and erythritol showed very limited growth promotion effects on all the strains after 24 h,probably because these strains lack the enzymes that hydrolyze glycosidic bonds.The growth promotion effects of FOS,XOS,GOS,inulin,stachyose,L-arabinose and lactitol were strain specific,presumably because of the different extracellular or intracellular enzymes secreted by each strain.Long-chain inulin slowed down the fermentation of Lactobacillus acidophilus,but was not applicable to the other strains.Despite being derived from the same source,the FOS from different manufactures showed different effects on the fermentation characteristics of strains,presumably because of the different contents of impurities they had.It was postulated that some prebiotics are beneficial to human health not by directly working on promoting the growth of lactobacilli or bifidobacteria in vivo;instead,they are degraded by other bacteria in the gut before being utilized by probiotic strains.