Propionic Acid and Sodium Benzoate Affected Biogenic Amine Formation, Microbial Community, and Quality of Oat Silage.

Tingting Jia,Ying Yun,Zhu Yu

doi:10.3389/fmicb.2021.750920

Abstract

Investigating the microbial communities and biogenic amine (BA) formation in silage is of vital for improving the quality and safety of oat silage. The present study evaluated the effects of propionic acid (P) and sodium benzoate (SB) on the quality properties, microbial communities, and BA formation in oat silage. Oat was harvested at boot stage and ensiled using P and SB as additives in mini silos, followed by 14 days of aerobic exposure. The results showed that P and SB improved fermentation quality of oat silage, increased the lactic acid content, and decreased pH value and ammonia nitrogen content. Putrescine, cadaverine, and tyramine were the dominant BAs in oat silage; spermidine and spermine were not detected. The control silage had the highest content of total biogenic amine (TBA, 2506.7 mg kg–1 DM), and decreased by 51.1 and 57.7% after adding P and SB, respectively. Moreover, a lower putrescine, cadaverine, and tyramine content and undesirable microbes, such as Caproiciproducens, Stenotrophomonas, Herbinix, and Enterobacter genera, were observed in P and SB silages, which was beneficial for oat silage quality. The fungal community of P silage was dominated by Monascus fuliginosus, and the temperature, pH and ammonia nitrogen content increased after exposure to air. Sedimentibacter, Herbinix, Caproiciproducens, Enterobacter, and Escherichia-Shigella were found to be positively correlated with BA formation in oat silage. Overall, P and SB effectively inhibit the undesirable microbes and BA formation in oat silage, the P silage exhibited lower aerobic stability than the SB silage.

Highlights

Ensiled whole plant oats are an important feedstuff for ruminants in large parts of the world
10.6 mg/kg dry matter (DM) of putrescine was detected in oat forage, while tryptamine, β-phenylethylamine, cadaverine, histamine, tyramine, spermidine, and spermine were not detected
No butyric acid was detected in the P and sodium benzoate (SB) silages, while 51.3 g/kg DM of butyric acid was detected in the control silage

Summary

Introduction

Ensiled whole plant oats are an important feedstuff for ruminants in large parts of the world. The quality and safety of silage are paramount and correlate with the fermentation pattern (Gollop et al, 2005). A fermentation process prevents forage deterioration and extends its preservation time since the organic acids released by lactic acid bacteria (LAB) inhibit the growth of undesirable microorganisms. The succession growth of LAB and their metabolic activities are essential for control the quality and safety of silage (Driehuis et al, 2018). The fermentation of oat silage is a complex biochemical process that includes interactions between various microorganisms (Duniere et al, 2017; Li et al, 2021). The activity of many microbes in silage may cause an extensive breakdown of amino acids into biogenic amines (McDonald and Whittenbury, 1973; Scherer et al, 2015)

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