AUTHOR=Mu Lin , Wang Qinglan , Cao Xin , Li Hui , Zhang Zhifei 

TITLE=The Potential of Pre-fermented Juice or Lactobacillus Inoculants to Improve the Fermentation Quality of Mixed Silage of Agro-Residue and Lucerne

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.858546

DOI=10.3389/fmicb.2022.858546

ISSN=1664-302X

ABSTRACT=<p>The objective of this study was to determine the effect of pre-fermented juice, <italic>Lactobacillus plantarum</italic>, and <italic>L</italic>. <italic>buchneri</italic> on chemical composition, fermentation, aerobic stability, dynamics of microbial community, and metabolic pathway of a mixture of lucerne, wheat bran (WB), and rice straw (RS). All mixtures were ensiled for 1, 3, 5, 7, 15, 30, and 45 days after treatment with uninoculated (control, C); <italic>L</italic>. <italic>plantarum</italic> [LP, 1 × 10<sup>6</sup> cfu/g of fresh weight (FW)]; <italic>L. buchneri</italic> (LB, 1 × 10<sup>6</sup> cfu/g of FW); LP + LB (LPB, 1 × 10<sup>6</sup> cfu/g of FW of each inoculant); and pre-fermented juice (J; 2 × 10<sup>6</sup> cfu/g of FW). Four lactic acid bacteria (LAB) species from three genera were cultured from the pre-fermented juice, with <italic>W. cibaria</italic> being dominant. The inoculants increased lactic acid (LA), decreased pH and ammonia nitrogen (AN) compared to C silage at earlier stages of ensiling, and high dry matter (DM) and water-soluble carbohydrate (WSC) content in inoculated silages. Adding LPB increased the abundance of <italic>L. plantarum</italic>, <italic>L. paralimentarius</italic>, and <italic>L. nodensis</italic>, resulting in the lowest pH. Pre-fermented juice enriched <italic>W. cibaria</italic>, <italic>L. sakei</italic>, <italic>L. parabrevis</italic>, <italic>Pseudomonas putida</italic>, and <italic>Stenotrophomonas maltophilia</italic>, mainly enhanced accumulation of acetic acid (AA) and LA, and decreased pH, crude protein losses, AN, and hemicellulose contents. <italic>L. buchneri</italic> and <italic>L. brevis</italic> had a high abundance in LB-treated and J silages, respectively, inhibited undesirable bacteria, and improved aerobic stability with more than 16 days. In addition, the metabolic pathways changed with time and <italic>L. buchneri</italic> inoculants promoted global metabolism. In conclusion, inoculations altered bacterial succession and metabolic pathways in silage; LB and pre-fermented juice enhanced ensiling by promoting pH reductions, enhancing concentrations of LA and AA, and extending aerobic stability more than 16 days.</p>