传统发酵食品中乳酸菌的分离鉴定、基因分型及优良菌株筛选

Isolation, identification and genotyping of lactic acid bacteria in traditional fermented food and dominate strains screening

对分离自传统发酵食品的40株乳酸菌进行16S r DNA鉴定、随机扩增多态性DNA(RAPD)菌株基因分型及产酸、产乙偶姻、降胆固醇、分解亚硝酸盐及1,1-二苯基-2-三硝基苯肼(DPPH)自由基清除能力进行研究。结果表明,40株乳酸菌中,20株植物乳杆菌(Lactobacillus plantarum),分为Ⅰ、Ⅱ、Ⅲ、Ⅳ4种型,Ⅲ型又分2个亚型;8株短乳杆菌(Lactobacillus brevis)、6株戊糖片球菌(Pediococcus pentosaceus)均呈现Ⅰ、Ⅱ、Ⅲ3种型,而6株耐久肠球菌(Enterococcus durans)呈现Ⅰ、Ⅱ2种型,显示了传统发酵食品中乳酸菌菌株的基因多样性。同种同型乳酸菌产酸、乙偶姻及DPPH自由基清除能力具有相似性;但同种不同型具有差异性。最终筛选出1株产酸(24.3 g/L)、乙偶姻(0.54 mg/m L)、分解亚硝酸盐(74.15%)、DPPH自由基清除能力(92.29%)均较强的植物乳杆菌SAV-JL7,以期为发酵食品风味及品质的改善提供参考。

40 strains of lactic acid bacteria isolated from traditional fermented food were identified by 16S rDNA,and genotyping by random amplified polymorphic DNA(RAPD).The acid production,acetoin production,cholesterol lowering,nitrite decomposition and DPPH free radical scavenging capacity were studied.The results showed that among the 40 lactic acid bacteria strains,20 strains were Lactobacillus plantarum,and they were divided intoⅠ,Ⅱ,ⅢandⅣtypes,and typeⅢwas divided into 2 subtypes;in addition,8 strains were Lactobacillus brevis,6 strains were Pediococcus pentosaceus,and they were all divided into 3 typesⅠ,Ⅱ,Ⅲ;6 strains were Enterococcus durans,and they were all divided into 2 typesⅠ,Ⅱ,which showed that the lactic acid bacteria isolated from traditional fermented food had genetic diversity.The same type of lactic acid bacteria had the similarity in acid production,acetoin production and DPPH free radical scavenging ability;different types were different in characteristic.A strain of L.plantarum SAV-JL7 with strong acid production(24.3 g/L),acetoin production(0.54 mg/ml),nitrite decomposition(74.15%)and DPPH free radical scavenging ability(92.29%)was screened finally,in order to provide reference for the improvement of the flavor and quality of the fermented food.