Screening of high quality thermotolerant lactic acid bacteria in stylo and the improving effect on fermentation quality of its silage

The objective of this experiment was to clarify the thermotolerant lactic acid bacteria in stylo silage and their effects on the quality of stylo silage, traditional microbial culture, isolation and screening. This was combined with 16s rRNA gene identification technology that was used to study the main species of high quality thermotolerant lactic acid bacterium in stylo silage and their physiological and biochemical characteristics. High quality lactic acid bacteria strains were selected as the inoculant for stylo silage making. The results showed that seven strains of high quality lactic acid bacteria were screened from stylo silage, which could withstand 45 ℃ high temperature, 7.5%NaCl salinity, pH 4.5 acidity, could use at least 11 carbon sources, and could produce acid quickly after two hours of inoculation. Genetic identification revealed that they were Enterococcus faecalis (strains S1, S2, S5 and S6), Weizmannia ginsengisoli (strain S3), and Pediococcus pentosaceus (strains S4 and S7), respectively. Enterococcus faecalis S1 strain and Pediococcus pentosaceus S4 strain were inoculated to stylo silage and ensiled for 30 d. This not only significantly reduced the dry matter loss of silage (P < 0.05), but also significantly decreased the pH value, butyric acid, and ammonia nitrogen contents (P < 0.05). The lactic acid contents of inoculation S1 or S4 strain were significantly higher than that in Lactiplantibacillus plantarum strain inoculation (P < 0.05). The number of Enterobacteriaceae decreased and there were no molds or yeasts detected among all silages of inoculation treatments. The crude protein content of the Enterococcus faecalis S1 inoculation group was significantly higher than that of the L. plantarum inoculation group (P < 0.05), which could effectively improve the fermentation quality of stylo silage and preserve more nutrients.