Characteristics of lactic acid bacteria, microbial community and fermentation dynamics of native grass silage prepared in Inner Mongolian Plateau

Abstract

IntroductionTo prepare high-quality silage, we studied the chemical composition, silage fermentation, characterization, and identification of lactic acid bacteria (LAB) associated with the silage fermentation of native grass on the Inner Mongolian Plateau.MethodsLAB were isolated from fresh native grass and their silage, and silages were prepared using a small-scale fermentation system with 2–3 cm length in plastic bags.ResultsThe dominant species of native grasses used were Stipa baicalensis, Leymus chinensis, Cleistogenes squarrosa, Melissilus ruthenicus and Pulsatilla turczaninovii, which contained 47.83–59.43 % moisture, 55.12–67.74 % neutral detergent fiber (NDF), and 8.72–14.55 crude protein (CP), and these nutrients did not change greatly during ensiling. Good preservation with a relatively low pH (below 4.44) and high (p < 0.05) lactic acid content (>0.58) was obtained after ensiling. Based on the morphological and biochemical characteristics, these isolates were divided into 12 groups (A-L). All isolate strains were gram-positive and catalase-negative bacteria that produce lactic acid from glucose. Group A-K were cocci, while group L was rod-shaped. Group A-E formed D-lactic acid, but group H-K formed L-lactic acid, and other groups formed DL-lactic acid. Group A-E were heterofermentative, and Group F-L were homofermentative types of LAB. According to the 16S rRNA gene sequences analysis, strains were identified as genus Leuconostoc (A, B, and C), Weissellla (D, E), Pediococcus (F, G), Enterococcus (H, I, J and K), and Lactiplantibacillus (L). Enterococcus (E.) faecium (29.17%, percentage of total isolates) and Pediococcus (P.) acidilactici (18.75%) were the most frequently occurring dominant species.DiscussionThis study suggests that the native grasses contained abundant LAB species, and they can be used as good-quality silages in animal husbandry. In addition, the strains P. acidilactici and E. faecium were the most frequently isolated from native grass silages as dominant species which can be a potentially excellent inoculant for native grass silage.

Effect of additives and moisture on the fermentation quality and bacterial community of high moisture ear corn

“…Subsequently, with the increase of moisture, the growth of Leucococcus was inhibited and the pH increased slightly, and the inhibition of Escherichia coli such as Serratia marcescens was weakened, and it competed with Lactobacillus and Leucococcus marcescens for nutrients, resulting in Escherichia coli such as Serratia marcescens becoming the dominant genus ( Heron et al, 2010 ; Weyker et al, 2016 ). Hou et al (2022) studied the changes in microbial communities during silage fermentation in native forages on the Inner Mongolian plateau, and their results also indicated that the abundance of Leucococcus significantly decreased with the increase in forage moisture.…”

Development of a hybrid bio-purification process of lactic acid solutions employing an engineered E. coli strain in a membrane bioreactor

“…LA is a major component of grass silage leachate at a typical concentration range between 22 and 38 g/L [12]. Since, a consortium of microorganisms is growing during the ensiling process both isomers D-and L-LA are present in the grass silage leachate [13,14]. Towards recovering LA from grass silage leachate, Ecker et al developed a LA recovery process that consisted of UF, two-step NF, ED, and reverse osmosis (RO) processes [15].…”