Effect of phenyllactic acid on silage fermentation and bacterial community of reed canary grass on the Qinghai Tibetan Plateau

Abstract

Background This study aimed to investigate the effect of phenyllactic acid as an additive on silage fermentation and bacterial community of reed canary grass (RCG, Phalaris arundinacea L.) on the Qinghai Tibetan Plateau. At the heading stage, RCG was harvested, chopped and ensiled in small bag silos. The silage was treated without (control, 1.0 g/mL sterile water, on a fresh matter basis (FM)) or with phenyllactic acid (PLA, 3 mg/mL, FM), antimicrobial additive (PSB, a mixture of potassium sorbate and sodium benzoate, 2%, FM), lactic acid bacteria inoculant (LABi, L. plantarum + L. curvatus, 1 × 106 cfu/g, FM) and PLA + LABi, and then stored in a dark room at the ambient temperature (5 ~ 15 °C) for 60 days. Results Compared with control, PLA decreased lactic acid, acetic acid and ammonia-N contents, and subsequently increased CP content of RCG silage. PLA enhanced the growth of lactic acid bacteria and reduced the count of yeasts (P < 0.05) in RCG silage, with reduced bacterial richness index (Chao1), observed operational taxonomic units and diversity index (Simpson). In relative to control, moreover, PLA and PLA + LABi increased the relative abundance of Lactococcus in RCG silage by 27.73 and 16.93%, respectively. Conclusions Therefore, phenyllactic acid at ensiling improved nutritional quality of RCG silage by advancing the disappearance of yeasts and the dominance of Lactococcus.

Effect of isolated lactic acid bacteria on the quality and bacterial diversity of native grass silage

“…In the high DM silage such as straw forage and native grass, the water activity of LAB is insufficient, so the silage fermentation is reduced due to insufficient metabolic water required for the growth of LAB (Borreani et al, 2018). Four LAB strains produced a large amount of LA and a certain amount of AA to decrease the pH and inhibit the activity of proteases in plants and microbes and reduce proteolysis using a series of substrates (Dong et al, 2022;Lu et al, 2022). Similarly, Si et al ( 2019) proved that the homo-and hetero-fermentative LAB inoculants could decrease the NH 3 -N content and pH during ensiling.…”

“…Functional KEGG profiles of bacterial communities were inferred using 16S rRNA gene sequences. The carbohydrate metabolic pathway was enriched after ensiling, which may be because of the fermentation of available carbohydrates into energy and short-chain fatty acids during ensiling (Zhao et al, 2022). The pyruvate metabolism, pentose phosphate pathway, and glycolysis/gluconeogenesis metabolic pathway dominated carbohydrate metabolism in native grass silage treatment of the three steppe types.…”