高产生物膜乳酸菌的筛选、鉴定及胞外多糖分泌条件的研究

Screening and Identification of High-producing Biofilm Lactic Acid Bacteria and Studies on the Conditions of Extracellular Polysaccharide Secretion

生物膜是微生物在受到外界不良环境影响时产生的一种自我保护机制,多数研究集中在病原菌和有害菌。乳酸菌作为食品工业和人体肠道中重要的微生物,若以被膜态生长则可以更好地发挥其益生作用。胞外多糖是乳酸菌生长过程中分泌出的代谢产物,是生物膜的主要成分,乳酸菌胞外多糖分泌越多,预示着其产生物膜的能力越强。本研究对课题组前期分离出的41株乳酸菌,以高产生物膜为指标,筛选和鉴定出10株优良菌株。以1株乳酸片球菌RJ2-1-4为研究对象,探讨改变培养基成分对胞外多糖合成量的影响。乳酸片球菌RJ2-1-4产胞外多糖的最佳培养基组合为:葡萄糖20 g/L,大豆蛋白胨20 g/L,磷酸氢二钾8 g/L,此时EPS产量达到最大值为(427.83±18.40)mg/L。

Biofilm is a self-protection mechanism produced by microorganisms when exposed to adverse external environment.Most researches focus on pathogenic bacteria and harmful bacteria.Lactic acid bacteria,as important microorganisms in the food industry and human intestinal tract,can better exert their probiotic effects if they are grown in a biofilm state.Extracellular polysaccharides(EPS)are metabolites secreted during the growth of lactic acid bacteria and are the main components of biofilms.The more secreted EPS from lactic acid bacteria,the stronger its ability to produce biofilms.In this study,41 strains of lactic acid bacteria were isolated in the early stage of the research group,and 10 excellent strains were screened and identified using the high-yield biofilm as an index.Taking a strain of Pediococcus lactis RJ2-1-4 as the research object,the effects of changing the composition of the medium on the amount of EPS were discussed.The optimal medium combination for EPS production by Pediococcus lactis RJ2-1-4 is:20 g/L glucose,20 g/L soy peptone,and 8 g/L dipotassium hydrogen phosphate.At this time,the EPS yield reaches the maximum value was(427.83±18.40)mg/L.