Dynamics of proteolysis, protease activity and bacterial community of Neolamarckia cadamba leaves silage and the effects of formic acid and Lactobacillus farciminis

Abstract

To investigate the reason for well preservation of protein in Neolamarckia cadamba leaves (NCL) during ensiling, fresh NCL were ensiled with or without addition of 2.0 mL/kg formic acid (FA) or 1.0 × 10⁹CFU/kg Lactobacillus farciminis (LF), and the dynamics of protease activity and microbial community were analyzed. Nonprotein-N, free amino acid, ammonia-N, the activities of carboxypeptidase and aminopeptidase, and bacterial diversity were low during NCL ensiling. Exiguobacterium dominated in NCL silage and its relative abundance increased while Enterobacter abundance decreased during ensiling. FA lowered (P < 0.05) pH and coliform bacteria number, while LF increased (P < 0.05) lactic acid bacteria number, lactic acid content and Lactobacillus abundance at the early stage of fermentation. In summary, protein in NCL can be well preserved during ensiling likely due to its low protease and bacterial activity, and FA and LF improve the quality of NCL silage in different ways.

Keywords: Bacterial community; Fermentation quality; Formic acid; Neolamarckia cadamba leaf; Protease.