Revealing the underlying potential mechanisms of lactic acid bacteria-mediated anaerobic fermentation of native grass by microbiome and metagenomic

This study aimed to decipher the dynamic changes in native grass (Meadow Steppe and Typical Steppe plants) silage occur in correlation with longitudinal alterations in microbial community structure during the fermentation process, this research also aimed to characterize the functional groups and the mechanisms underlying the effects of different lactic acid bacteria (LAB, including Lactobacillus graminis, Lactobacillus plantarum and Pediococcus acidilactici) strains on the native grass silage. All LAB strains were added alone at 105 cfu/g of the fresh materials. The author combined 16S rRNA amplicon sequencing and metagenomic sequencing with temporal sampling to investigate the succession of the bacterial community and the influences of the LAB on the fermentation quality, aiming to elucidate the underlying mechanisms behind LAB-mediated native grass silage production. Results showed that during the natural ensiling process, the most of the chemical compositions and fermentation quality markedly (p < 0.05) decreased and increased after 60 days of ensiling, respectively. The bacterial composition shifted significantly from Pantoea in raw materials to Lactobacillus, Lactococcus and Pediococcus in silages, and the fermentation was determined by the LAB. Then some LAB strains were isolated form the native grass silage and the native grass was treated with these isolated LAB strains, a clear differentiation in bacterial communities was observed across treatments, with Lactobacillus dominating the fermentation process. The metagenomic analysis revealed the distinct fermentation quality were driven by the LAB strains due to the significantly different gene profiles and metabolic function. This study has identified fermentation quality and microbial communities in native grass silage during anaerobic fermentation. The ensiling performance of native grass silage was dominated by the Lactobacillus plantarum, which could provide evidence for the importance of LAB in the native grass silage preservation.