Factors influencing the distribution of lactic acid bacteria on Pennisetum grasses

Abstract

AbstractSuccessful silage production depends on the promotion of lactic acid fermentation and one of the key factors influencing the fermentation quality of silage is lactic acid bacteria (LAB). Therefore, epiphytic LAB on grasses play an important role in silage production. The present research investigated the distribution of LAB on Pennisetum spp. and factors influencing its presence. Lactic acid bacteria on four grass cultivars, cv. MT‐1, cv. Mott, cv. Reyan No. 4 (Reyan) and cv. Guimu No. 1 (Guimu), were investigated by both culture‐dependent methods and 16S rRNA amplicon sequence analysis and polymerase chain reaction‐denaturing gradient gel electrophoresis (PCR‐DGGE). Mott grass had significantly lower contents of dry matter and lower pH and higher water‐soluble carbohydrates (WSC) content than the other three cultivars (P < 0.05). Mott also epiphyted the largest number of LAB (2.56 × 103 cfu g−1), while MT‐1 supported the least (41 cfu g−1). A diversity of LAB were recovered from the species including the following proportional representation: 33.4% Lactobacillus plantarum, 8.3% Lactobacillus pentosus, 8.3% Lactococcus lactis, 8.3% Leuconostoc citreum, 25.0% Weissella confusa and 16.7% Weissella cibaria on Mott, 20.0% L. plantarum, 20.0% L. pentosus and 60.0% Lc. lactis on MT‐1, 83.3% L. plantarum and 16.7% Lc. lactis on Reyan, 16.7% L. plantarum and 83.3% Lc. lactis on Guimu. The DGGE analyses of rRNA amplicons also revealed a similar distribution of these species. While the species composition and abundance of LAB differed among the four grasses. The number of LAB on grasses was positively correlated with the WSC content in the grasses (P < 0.01), and negatively correlated with the pH of the grasses (P < 0.05).