Enzyme additives influence bacterial communities of Medicago sativa silage as determined by Illumina sequencing

Zongfu Hu,Zongfu Hu,Huaxin Niu,Shuguo Li,Jie Chang,Qing Tong,Jianhua Yu,Deying Ma

doi:10.1186/s13568-020-01158-5

Zongfu Hu, Zongfu Hu + Show 6 more

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https://doi.org/10.1186/s13568-020-01158-5

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Abstract

The goal of the present study was to evaluate the effects of enzymes (cellulase combined with galactosidase) and their combination with Lactobacillus plantarum (LP) on bacterial diversity in alfalfa silages using high-throughput sequencing. Alfalfa forages were treated with or without cellulase + ɑ-galactosidase (CEGA), cellulase + LP (CELP), or ɑ-galactosidase + LP (GALP). After 56 days of ensiling, all treated silages exhibited improved fermentation quality, as reflected by decreased pH, ammonium-N and increased lactic acid levels compared to the control silage (P < 0.05). Enzymatic treatment improved nutrient value by increasing crude protein levels and decreasing neutral detergent fibre (NDF) levels (P < 0.05). Silage treatment significantly altered the bacterial community, as determined by PCoA (P < 0.05). Lactic acid bacteria (LAB) dominated the bacterial community of the treated silage after ensiling. The dominant bacteria changed from Garciella, Enterococcus, Lactobacillus and Pediococcus in the control silage to Lactobacillus and Pediococcus in the CEGA silage and Lactobacillus in the CELP and GALP silages. Collectively, these results suggest that treatment with both enzymes alone and in combination with inoculants greatly increased the abundance of LAB, with Enterococcus, Lactobacillus and Pediococcus observed in the silage treated with enzymes alone (CEGA) and Lactobacillus observed in the silage treated with a combination of enzymes and inoculants (CELP and GALP).

Highlights

Alfalfa is a major forage for animal feed and is widely used worldwide
Co., Ltd., Beijing, China) plus ɑ-galactosidase (15,000 IU, SD-124, Challenge Co., Ltd., Beijing, China) (CEGA) at a dose of 5 g/kg fresh forage for each enzyme; (3) cellulase at a dose of 5 g/kg forage combined with 1 × 107 cfu/g FM of freshly cultured L. plantarum (BNCC337987, Bnbio Co., Ltd., Beijing, China) (CELP); and 4) ɑ-galactosidase at a dose of 5 g/kg forage, combined with 1 × 107 cfu/g FM of L. plantarum (GALP)
Effects of enzyme and enzyme + inoculant treatments on silage fermentation quality The treatment of silage with enzymes alone or in combination with L. plantarum affected the Lactic acid bacteria (LAB) cfu of silage after 56 days

Summary

Introduction

Alfalfa is a major forage for animal feed and is widely used worldwide. Due to the substantial dry matter (DM) loss that occurs during the hay-making process, ensiling is an efficient method for preserving the nutritive value of alfalfa (Oliveira et al 2017; Muck et al 2018). In addition to bacterial inoculants, enzymes such as cellulase, hemicellulase, pectinase, and amylase (Tengerdy et al 2010; Kozelov et al 2008) are extensively used in the ensiling process (Muck et al 2018; Dunière et al 2013). The most commonly used enzymes are cellulases, which are widely recognized for their applications in forage preservation (Arriola et al 2011; ContrerasGovea et al 2011). These enzymes used for ensiling have the ability to degrade cell walls and release soluble sugars, which are essential substrates for LAB growth (Muck et al 2018). A study by Selmer-Olsen et al (1993) showed that cellulase/hemicellulase enzymes improve the silage quality of perennial ryegrass

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