Isolation, Identification of a Lactic Acid Bacteria Strain and Its Effect on Fermentation of Broad Bean Straw Silage

Purpose To screen and isolate lactic acid bacteria (LAB) with promising bacteriostatic performance from Pennisetum giganteum in silage, and to study their effects on fermentation of board bean straw.

Methods LAB were isolated and purified from the silage products of P. giganteum. Escherichia coli K88, Salmonella typhimurium and Staphylococcus aureus were used as indicator bacteria to obtain antagonistic bacteria. The LAB were identified based on colony morphology, Gram staining and 16S rDNA. The characteristics of LAB were identified by growth curve, acid producing ability, and antibiotic resistance. The LAB with strong antibacterial ability were used to ferment broad bean straw, and the conventional nutritional components, sensory evaluation and mycotoxin content were analyzed to determine the effect of the screened LAB on silage fermentation.

Results A strain R-01 with strong inhibitory effect on E. coli K88, S. typhimurium and S. aureus was screened from silage product of P. giganteum. It was identified as Lactobacillus plantarum, which had good growth, good acid-producing property, strong bacteriostatic ability and strong resistance to many antibiotics. As an additive, R-01 had some unexceptionable characteristics on improving nutritional value of broad bean straw and reducing the content of mycotoxins in silage.

Conclusion The R-01 screened and identified has excellent characteristics on growth, acid production, bactriostasisk and drug resistance, which can acidify the silage rapidly, effectively maintain the nutrient composition in silage, reduce the mycotoxin content and improve the overall effect of silage, suggesting a promising strain for fermentation in silage.