Microbial network and fermentation modulation of Napier grass and sugarcane top silage in southern Africa

Abstract

Feed shortage in the tropics is a major constraint to the production of livestock products such as milk and meat. In order to effectively utilize of local feed resources, the selected lactic acid bacteria (LAB) strain was used to prepare Napier grass and sugarcane top silage. The results showed that the two silages inoculated with LAB formed a co-occurrence microbial network dominated by Lactiplantibacillus during the fermentation process, regulated the microbial community structure and metabolic pathways, and improved the silage fermentation quality. This is of great significance for alleviating feed shortage and promoting sustainable production of livestock.

Keywords: PacBio SMRT; fermentation modulation; lactic acid bacteria screening; microbial co-occurrence network; tropical silage.

Fig 1

Venn diagram of OTU numbers at 97% sequence identity in Napier grass (a) and sugarcane top (b) before and after ensiling. OTU, operational taxonomic unit; MO1, L. plantarum MO1; LP1, L. plantarum LP1.

Fig 2

The relative abundance of the bacterial community at the genus (a) and species (b) levels in the NG and ST before and after ensiling. NG, Napier grass; ST, sugarcane top; MO1, L. plantarum MO1; LP1, L. plantarum LP1.

Fig 3

ANOVA four bacterial genera (a) Lactiplantibacillus, (b) Clostridium sensu stricto 12, (c) Cellulomonas and (d) Serratia with significant changes in Napier grass silage. LP1, L. plantarum LP1; MO1, L. plantarum MO1.

Fig 4

The impacted KEGG metabolic pathways in the Napier grass before and after ensiling (a) and LP1- and MO1-treated silage (b). KEGG, Kyoto Encyclopedia of Genes and Genomes; LP1, L. plantarum LP1; MO1, L. plantarum MO1.

Fig 5

Microbial co-occurrence network at the species level related to silage fermentation of Napier grass. f, family; g, genus.

Fig 6

Correlation heatmap and hierarchical cluster analysis between bacterial community and terminal fermentation products in the Napier grass silage. LAB, lactic acid bacteria; NH₃-N, ammonia nitrogen.