Natural lactic acid bacterial community and screening of high-quality lactic acid bacteria in silage in southwest China

To improve the quality of silage in hot and humid areas, the community of 227 natural lactic acid bacteria isolated from silage in a hot and humid areas of Southwest China was analyzed. Four high-quality lactic acid bacteria (LAB) strains (LP149, LS358, LR753, and LPA761) were screened based on their growth activity and acid-producing ability under high temperature, and their physiological and biochemical characteristics, growth, and acid-production efficiency were determined. Lactobacillus plantarum was the most common LAB strain in the silage (62.55%), followed by L. rhamnosus and L. paracasei, accounting for 13.21% and 9.25% of the total strains, respectively. The four selected strains were gram-positive, catalase-negative, and rod shaped, and could grow at pH 3.5 and 45℃. According to the physiological and biochemical characteristics and 16S rRNA sequencing analysis, the four strains (LP149, LS358, LR753, and LPA761) were identified as L. plantarum, L. salivarius, L. rhamnosus, and L. paracasei, respectively. The results of growth and acid-production efficiency of the strains at 37 and 45 ℃ demonstrated that the four screened LAB strains exhibited good adaptability at high temperatures (45 ℃). They not only grow fast, with strong acid-producing ability and salt-tolerance, but also exhibited good adaptability to an acidic environment. This indicated they could be candidate strains for subsequent high temperature silage tests.