Modulation of Metabolome and Bacterial Community in Whole Crop Corn Silage by Inoculating Homofermentative Lactobacillus plantarum and Heterofermentative Lactobacillus buchneri

Abstract

The present study investigated the species level based microbial community and metabolome in corn silage inoculated with or without homofermentative Lactobacillus plantarum and heterofermentative Lactobacillus buchneri using the PacBio SMRT Sequencing and time-of-flight mass spectrometry (GC-TOF/MS). Chopped whole crop corn was treated with (1) deionized water (control), (2) Lactobacillus plantarum, or (3) Lactobacillus buchneri. The chopped whole crop corn was ensiled in vacuum-sealed polyethylene bags containing 300 g of fresh forge for 90 days, with three replicates for each treatment. The results showed that a total of 979 substances were detected, and 316 different metabolites were identified. Some metabolites with antimicrobial activity were detected in whole crop corn silage, such as catechol, 3-phenyllactic acid, 4-hydroxybenzoic acid, azelaic acid, 3,4-dihydroxybenzoic acid and 4-hydroxycinnamic acid. Catechol, pyrogallol and ferulic acid with antioxidant property, 4-hydroxybutyrate with nervine activity, and linoleic acid with cholesterol lowering effects, were detected in present study. In addition, a flavoring agent of myristic acid and a depression mitigation substance of phenylethylamine were also found in this study. Samples treated with inoculants presented more biofunctional metabolites of organic acids, amino acids and phenolic acids than untreated samples. The Lactobacillus species covered over 98% after ensiling, and were mainly comprised by the L. acetotolerans, L. silagei, L. parafarraginis, L. buchneri and L. odoratitofui. As compared to the control silage, inoculation of L. plantarum increased the relative abundances of L. acetotolerans, L. buchneri and L. parafarraginis, and a considerable decline in the proportion of L. silagei was observed; whereas an obvious decrease in L. acetotolerans and increases in L. odoratitofui and L. farciminis were observed in the L. buchneri inoculated silage. Therefore, inoculation of L. plantarum and L. buchneri regulated the microbial composition and metabolome of the corn silage with different behaviors. The present results indicated that profiling of silage microbiome and metabolome might improve our current understanding of the biological process underlying silage formation.

Effects of Lactic Acid Bacteria Isolated From Rumen Fluid and Feces of Dairy Cows on Fermentation Quality, Microbial Community, and in vitro Digestibility of Alfalfa Silage

“…The bacterial community was usually dominated by Lactobacillus in well-fermented silages (Hao et al, 2018;Xu et al, 2018;Yan et al, 2019). It is well established that Lactobacillus plays a critical role in silage fermentation by producing LA, reducing pH, and decreasing the relative abundance of undesirable bacteria.…”

Effect of 3-Phenyllactic Acid and 3-Phenyllactic Acid-Producing Lactic Acid Bacteria on the Characteristics of Alfalfa Silage

“…However, until now, limited studies have been reported on PLA. Most of the reports analyzed gramineae silage [27], and the PLA was positively related to the abundance of L. acetotolerans in whole-crop corn silage [20]. In this work, the PLA content was related to the content of NH 3 -N, indicating that the PLA produced during alfalfa ensiling was different from that produced during corn ensiling.…”

“…Xu et al found PLA and other metabolites with bacteriostatic activity in whole-crop corn silage, but the treatments had no significant effect on the metabolites [20]. The PLA content was recorded in frozen, grass-dominated crop silages inoculated with LAB [27].…”

“…As a newly found antifungal compound, PLA showed inhibitory effects toward yeast and mold species, such as Penicillium, Aspergillus, Candida, Rhodotorula, and Rhizopus species [10][11][12]19]. PLA was also detected in silages, and its presence might relate to LAB [20]. Xu et al reported that the content of PLA in silage was probably produced by L. acetotolerans and positively correlated with L. plantarum [20].…”

“…PLA was also detected in silages, and its presence might relate to LAB [20]. Xu et al reported that the content of PLA in silage was probably produced by L. acetotolerans and positively correlated with L. plantarum [20]. It was speculated that the antifungal activity of LAB strains was positively related to the metabolic content of PLA [12].…”