Screening and biological characteristics of excellent acid-producing lactic acid bacteria in corn silage
Taking corn silage naturally fermented for 60 d in the pasture of Ulanqab City,Inner Mongolia Autonomous Region as the research object,the bacterial flora structure was analyzed through high-throughput sequencing technology,and the dominant acid-producing strains were screened through MRS-CaCO3 plate calcium dissolution method and acid production capacity measurement.The screened strains were identified by morpho-logical observation and molecular biological techniques,and their growth characteristics,acid,bile salt,alcohol,artificial gastrointestinal fluid toler-ance and antibacterial ability were studied.The results showed that Acetobacter,Lactobacillus and Bacteroides were the dominant bacteria in corn silage.A total of 5 dominant acid-producing bacteria were obtained after screening,among them,the strains Yml,Ym20 and Ym21 were identified as Lactobacillus paracasei,and strains Ym22 and Ym35 were identified as Lactobacillus pentosus.The optimal initial pH of the 5 dominant acid-pro-ducing bacteria was all 6.0,and the optimal temperature was 35 ℃ except for the strain Ym35 which was 40 ℃.The strain Ym22 had higher bile salt tolerance and the strongest ability to inhibit Escherichia coli,the strain Ym35 had good acid and artificial intestinal juice tolerance,the stain Ym20 had good tolerance to artificial gastric juice,the strain Ym1 had the strongest inhibition ability against Bacillus subtilis and Staphylococcus aureus,and the ethanol tolerance of strain Ym21 was the highest.The 5 strains of lactic acid bacteria could be used as the source of compound preparation bacteria for the subsequent preparation of high quality corn silage.
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