一株高产酸乳酸菌的分离鉴定及生物学特性研究

摘要

利用MRS选择性培养基从豆清发酵液中分离筛选乳酸菌.经初筛得到5株乳酸菌,通过比较不同乳酸菌在同一条件下的pH和产乳酸量复筛得到一株产酸较高、pH较低的优势产酸乳酸菌,对其编号为M-6.根据菌株的形态学观察、生理生化试验以及16S rRNA基因序列分析鉴定,初步将该菌株鉴定为肠膜明串珠菌(Leuconostoc mesenteroides strain M-6).对其进行生物学特性研究,发现菌株M-6的最适生长温度在30℃,适宜pH范围为5.5 ～ 8.5,菌株在该温度下发酵20 h后菌液OD600nm高达1.2917,pH低至4.16(总酸),且菌株M-6有一定的耐盐受性,当NaC1浓度大于3％时,菌株生长受到明显抑制.因分离得到的肠膜明串珠菌M-6具有较强的产酸能力,可利用其发酵制备豆腐凝固剂,在豆制品生产领域具有良好的应用前景.%In the experiment,the MRS selective medium was used to isolate lactic acid bacteria from naturally fermented soybean broth.Five kinds of lactic acid bacteria were isolated.Comparing the pH value and the amount of lactic acid produced by these strains under same conditions,a lactic acid bacterium named strain M-6,which had high acid-producing capability and low pH,was screened out.After morphological observation,physiological and biochemical test and combined with 16S rRNA gene sequence analysis identification,this strain was identified as leuconostoc mesenteroides strain M-6.After studied on biological characteristics,it was discovered that,the optimum growth temperature of strain M-6 was at 30℃,and optimum pH range was 5.5-8.5.After 20 hours fermentation,the OD600nm value reached 1.2917 and the pH value reached 4.16.Strain M-6 had a certain salt tolerance,but when the concentration of NaCl was greater than 3％,the growth of strain M-6 was significantly inhibited.As the leuconostoc mesenteroides strain M-6 has a strong acid-producing capability,its fermentation products can be used as a tofu coagulant,which has a good potential in soybean production industry.