肠膜明串珠菌HDE1的分离鉴定及其胞外多糖抗氧化和牛奶凝结特性研究

Isolation,Identification of Leuconostoc mesenteroides HDE1 and Antioxidation and Milk Coagulability of Its Extracellular Polysaccharide

为了拓展产乳酸菌胞外多糖的来源,获得来源明确、产量稳定、具有优良生物学特性的乳酸菌胞外多糖。本研究从自制橘子发酵液中利用产黏菌落法分离筛选得到一株高产胞外多糖的乳酸菌,综合形态学观察及16S rDNA序列分析结果、API 50 CHL试验,对其进行鉴定,利用抗氧化及牛奶凝结试验研究了该乳酸菌胞外多糖的抗氧化及牛奶凝结等特性。结果表明,本研究获得了一株肠膜明串珠菌(Leuconostoc mesenteroides),该菌株16S rDNA序列片段长度为1444 bp,GenBank登录号为OM302141。菌株HDE1胞外多糖的总糖、蛋白质、糖醛酸含量分别为41.73%±1.74%、0.29%±0.03%和7.69%±0.42%。该胞外多糖在浓度为3 mg/mL时展现出良好的抗氧化活性,当胞外多糖浓度为5 mg/mL时DPPH自由基清除能力达到50.00%±0.05%,ABTS+自由基清除能力达到40.00%±0.02%,H_(2)O_(2)^(-)自由基清除能力超过了50%,羟基自由基清除能力达到49.96%±0.03%,胞外多糖的总还原力为38.82%±0.09%。牛奶凝结研究结果表明,HDE1在36 h能够使添加3%(w/v)蔗糖的脱脂牛奶完全凝结。这些结果表明菌株HDE1胞外多糖具有良好的抗氧化和牛奶凝结特性,在食品、医药及益生领域展现出良好应用潜力。

In order to expand the source of exopolysaccharides(EPS)from lactic acid bacteria,obtain EPS from lactic acid bacteria with clear source,stable yield and excellent biological characteristics.In this study,a strain of lactic acid bacteria with high EPS production was isolated and screened from self-made orange fermentation liquid by slime producing colony method.Morphological observation,16S rDNA sequence analysis results and API 50 CHL test were combined to identify the strain.Antioxidant and milk coagulation characteristics of the lactic acid bacteria EPS were studied by antioxidant and milk coagulation test.Results showed that:A 16S rDNA fragment of Leuconostoc mesenteroides with 1444 bp was obtained,and its GenBank number was OM302141.The contents of total sugar,protein and uronic acid in strain HDE1 EPS were 41.73%±1.74%,0.29%±0.03%and 7.69%±0.42%,respectively.The EPS showed good antioxidant activity when the concentration was 3 mg/mL.When the concentration of EPS was 5 mg/mL,the scavenging ability of DPPH,ABTS+and H_(2)O_(2)^(-)free radical reached 50.00%±0.05%,40.00%±0.02%and more than 50%.The hydroxyl scavenging ability was 49.96%±0.03%,and the total reducing power of EPS was 38.82%±0.09%.Milk curdling results showed that HDE1 could make skim milk with 3%(w/v)sucrose coagulate completely at 36 h.These results indicated that strain HDE1 EPS had good antioxidant and milk condensation properties,showing good application potential in food,medicine and probiotics.