西藏豆科牧草青贮饲料中耐低温优良乳酸菌的筛选

Isolation and identification of low temperature-tolerant lactic acid bacteria from legume silages in Tibet

本研究对西藏地区豆科牧草青贮饲料中的乳酸菌进行分离、鉴定,以期得到优良的乳酸菌菌株.以苜蓿和箭薚豌豆青贮饲料为试验材料,共分离得到6 株同型发酵乳酸菌,经传统微生物培养和16SrRNA 序列分析,3 株（LCG9,CG35和AG11）为戊糖片球菌,2株（LCG3和LAG1）为植物乳杆菌,1株（LA3）为弯曲乳杆菌;除AG11和LAG1在5℃,LCG9和AG11在pH3.0和8.0生长微弱外,其余乳酸菌菌株均在5～20℃,pH3.0～8.0及3.0%和6.5% NaCl培养液中生长良好.从耐低温特性、产酸能力和发酵速率3个指标考虑,植物乳杆菌LCG3最适宜用于西藏青贮饲料生产的乳酸菌菌种.

The objectives of this study were to identify lactic acid bacteria with desirable attributes by isolating and identifying lactic acid bacteria (LAB)from legume silages in Tibetan Plateau.A total of 6 homofermentia-tive lactic acid bacteria were isolated from alfalfa (Medicago sativa )and common vetch (Vicia sativa )silage. Strains LCG9,CG35 and AG11 were identified as Pediococcus pentosaceus ,strains LCG3 and LAG1 as Lacto-bacillus plantarum and strain LA3 as Lactobacillus curvatu .Conventional microbial identification methods and 16S rRNA sequencing analyses were used to identify different strains.The selected strains were grown in a range of conditions;temperature 5 -20℃,pH 3.0 -8.0 and NaCl 3.0% and 6.5%.LCG9 and AG11 grew weakly at 5℃ while LCG9 and AG11 were inactive at pH 3.0 and pH 8.0.LCG3 was identified as the best strain to use as a silage additive in Tibet due to its unique tolerance of low temperature,high lactic acid produc-tion and rapid reproductive rate.