Analysis of microbial populations in alfalfa silage and screening and identification of the main strains

Alfalfa is the most important source of roughage protein for ruminants. It has its optimal feed value when used as silage. The purpose of this study was to analyze the main microbial composition of alfalfa silage, to screen the main strains of alfalfa silage on this basis, and to develop microbial additives suitable for alfalfa silage. Firstly, the microbial population and community composition in natural semi-dry alfalfa silage were analyzed by macrogenomic sequencing. Based on this analysis, MRS, NA, LB, PDA and Mai's media were used to screen microbial species from natural alfalfa silage fodder, under both aerobic and anaerobic culture conditions. The species and genera of the screened microorganisms were identified by morphological and molecular biological methods. The results showed that the main microbial communities (identified at the genus level) in alfalfa silage were Oceanobacillus, Lactobacillus, and Bacillus, which accounted for 24.9%, 14.3%, and 13.9% of the detected microorganisms, respectively. A total of 30 strains were isolated on different media, under aerobic and anaerobic conditions, at 37 ℃. After morphological analysis and conservative sequence alignment, 15 strains were identified as L. plantarum; 8 strains were identified as B. subtilis; 2 strains were identified as B. licheniformis; and 1 each was identified as Pediococcus acidilactici, Enterococcus faecium, B. aryabhattai, B. pumilus and B. amyloliquefaciens. The selected strains and their identification results were consistent with the results of macrogenomic sequencing analysis, indicating the reliability of these results.