饲料玉米中优质乳酸菌的分离和鉴定

目的]从饲料玉米中筛选适合做青贮饲料添加剂的高效乳酸菌。方法]用MRS＋CaCO3固体培养基筛选乳酸菌,经形态学和生理生化试验进行初步鉴定,测定其产酸效率;挑选出12株产酸率强的乳酸菌进行耐盐和耐酸能力的测定,并对其进行16 S rDNA鉴定。结果]从饲料玉米中共分离得到44株乳酸菌,12株产酸能力强的菌株经生理生化试验鉴定分别属于明串珠菌属、乳杆菌属和肠球菌属,且12株菌株都具有良好的耐盐、耐酸能力。经16 S rDNA鉴定：A4、B9、B11、B12和B14为植物乳杆菌;A1、A2、A7、A11和B8为肠膜明串珠菌葡聚糖亚种;A8和A9为兼性肠球菌。结论]从饲料玉米中筛选出具有较强产酸能力的乳酸菌,作为青贮饲料添加剂。

Isolation and Identification of High-Quality Lactic Acid Bacteria in Forage Corn

Objective]To screen suitable lactic acid bacteria strains from forage corn which can be used as silage additives.Method]The lactic acid bacteria strains were isolated by inoculation on MRS solid medium containing calcium carbonate,and they were preliminarily identified through morphological,physiological and biochemical experiments.The acid production efficiency was determined.Twelve strains having better acid-production ability were selected,and their salt tolerance and acid tolerance were detected.The sequences of their 16 S rDNA were also analyzed.Result]A total of 44 lactic acid bacteria strains were isolated from the forage corn.As evidenced by the physiological and biochemical experiments,the twelve strains having better acid-production ability belonged to Leuconostoc,Lactobacillus and Enterococcus,respectively,and they had strong salt tolerance and acid tolerance.According to the sequences of 16 S rDNA,A4,B9,B11,B12 and B14 were Lactobacillus plantarum;A1,A2,A7,A11 and B8,Leuconostoc mesenteroides dextran subspecies;and A8 and A9,Enterococcus hirae.Conclusion]The lactic acid bacteria strains with better acid-production ability isolated from forage corn can be developed into silage additives.