嗜热链球菌KLDS SM胞外多糖生物合成途径的分析

摘要

In order to expiore the ability of exopolysaccharide synthesis of Streptococcus thermophilus KLDS SM based on gene level,three aspects of sugar transport systems,sugar nucleotide synthesis and exopolysaccharide gene cluster structure were analyzed in detail.The results showed that the bacteria coull transport glucose,lactose,sucrose,trehalose and mannose,had the enzymes for glucose,lactose,fructose,sucrose,trehalose and mannose metabolism.The bacteria had the potential for exopolysaccharide precursor synthesis,including UDP-glucose,UDP-galactose,UDP-N-acetvl glucosamiue,UDP-galactofuranose and dTDP-rhamnose.Furthermore,sequence alignment analysis showed that the exopolysaccharide sequence of this bacteria had a high identity to that of strain ASCC 1275,and preliminary determination of exopolysaccharide yield was about 331 mg/mL.The results showed that the strain was a potential EPS producing strain and had great potential in industry.%为了从遗传水平上探究嗜热链球菌KLDS SM合成胞外多糖(EPS)的能力,本研究从糖被转运进入胞内、糖核苷酸合成及EPS基因簇三方面所涉及的基因进行了相关分析.结果发现,该菌能够转运葡萄糖、乳糖、蔗糖、海藻糖及甘露糖5种糖,具有代谢葡萄糖、乳糖、果糖、蔗糖、海藻糖与甘露糖形成糖酵解中间代谢产物的酶类,拥有合成EPS前体物质UDP-葡萄糖、UDP-半乳糖、UDP-N-乙酰基葡糖胺、UDP-呋喃半乳糖与dTDP-鼠李糖的潜力.同时序列比对分析发现该菌具有一个与高产EPS的菌株ASCC 1275一致性极高的EPS基因簇,且EPS初步产量测定约为331 mg/mL,表明该菌是一株高产EPS潜力菌株,具有较大的应用潜能.