Inoculation with Lentilactobacillus buchneri alone or in combination with Lentilactobacillus hilgardii modifies gene expression, fermentation profile, and starch digestibility in high-moisture corn.

Inoculants combining Lentilactobacillus buchneri and Lentilactobacillus hilgardii have been shown to improve the aerobic stability of high-moisture corn (HMC) and whole-plant corn silage, but the mode of action of this co-inoculation remains to be elucidated. This study used metatranscriptomics to evaluate the effects of inoculation with L. buchneri alone or combined with L. hilgardii on the bacterial community, gene expression, fermentation profile, and starch digestibility in HMC. High-moisture corn not inoculated (Control) or inoculated with L. buchneri NCIMB 40788 (LB) or L. buchneri NCIMB 40788 combined with L. hilgardii CNCM-I-4785 (Combo) was ensiled in mini silo bags for 30, 60, 120, and 180 days. The fermentation profile was evaluated at all time points. Metatranscriptomics was performed on samples collected on day 120. Combo had a greater alpha diversity richness index of contigs than LB and Control, and inoculation with Combo and LB modified the beta-diversity of contigs compared to Control. Out of 69 genes of interest, 20 were differentially expressed in LB compared to Control and 25 in Combo compared to Control. Of those differently expressed genes, 16 (10 of which were associated with carbohydrate metabolism and six with amino acid metabolism) were differently expressed in both LB and Combo compared to Control, and all those genes were upregulated in the inoculated silages. When we compared Combo and LB, we found seven genes expressed differently, four associated with carbohydrate metabolism and downregulated in Combo, and three associated with amino acid metabolism and upregulated in Combo. At day 120, the inoculated silages had more culturable lactic acid bacteria, higher Lactobacillus relative abundance, and lower Leuconostoc relative abundance than Control. The concentration of acetic acid remained low throughout ensiling in Control, but in LB and Combo, it increased up to day 60 and remained stable from day 60 to 180. The 1,2-propanediol was only detected in LB and Combo. Inoculation did not affect the concentration of starch, but starch digestibility was greater in Combo than in Control. Inoculation of HMC with Combo modified the gene expression and fermentation profile compared to Control and LB, improving starch digestibility compared to uninoculated HMC.

Changes to the microbiome of alfalfa during the growing season and after ensiling with Lentilactobacillus buchneri and Lentilactobacillus hilgardii inoculant.

AIMS: This study evaluated changes in epiphytic microbial population of alfalfa (Medicago sativa) during the growing season. First cut forage was harvested to study the effects of an inoculant combining two obligate heterofermentative lactic acid bacteria strains on the bacterial and fungal communities and the fermentation of alfalfa silage. METHODS AND RESULTS: The epiphytic microbiome of alfalfa was evaluated 10-times during the growing season. Alfalfa wilted to 395.0 g/kg was treated with water (Control) or with a combination of L. buchneri NCIMB 40788 and L. hilgardii CNCM-I-4785 (LBLH). Mini-silos were opened after 1, 4, 8, 16, 32, and 64 days of ensiling. The relative abundance (RA) of the epiphytic bacterial and fungal families varied during the growing season. After 1 day, Weissella was the most abundant genus and present at similar RA in the two treatments (average 80.4%). Compared with Control, LBLH had a higher RA of Lactobacillus at day 1, 16, 32, and 64, and a lower RA of Weissella from day 8 to 64. Control contained more bacteria belonging to the Enterobacteriales than LBLH up to day 16. Inoculated silage had more acetate than Control at day 32 and 64. The fungal population were similar between treatments. The enhanced development and dominance of Lactobacillus in inoculated silage led to greater accumulation of acetate and propionate, which reduced the numbers of culturable yeasts but did not markedly affect the fungal community structure. CONCLUSIONS: The bacterial community composition of alfalfa stands in the filed changed over time and was affected by cutting. For the ensiling trial, inoculation modified the composition of the bacterial community of alfalfa, increasing the RA of Lactobacillus while reducing the RA of Weissella and of Enterobacteriaceae. SIGNIFICANCE AND IMPACT OF STUDY: Inoculation increased the RA of Lactobacillus, hampering the dominance of Weissella in the early stages of ensiling, improving antifungal compounds production and reducing the numbers of culturable yeasts.

Effects of hybrid, kernel maturity, and storage period on the bacterial community in high-moisture and rehydrated corn grain silages.

This study evaluated changes in the bacterial community in high-moisture and rehydrated corn grain silage, and their correlation with fermentation quality attributes in distinct corn hybrids, the storage period, and kernel maturity at plant harvest. Most silages achieved good fermentation (pH<4.2). Rehydrated corn had a higher pH across all storage periods evaluated and increased dry matter losses. Leuconostoc and Lactococcus were the dominant genera in fresh material, while Lactobacillus and Acetobacter were prevalent in silages. Clostridium and Enterococcus prevailed in rehydrated corn after 120 days storage, and Clostridium was highly and positively correlated with acetone, butyric acid, and 2,3-butanediol contents. The storage period and kernel maturity were the most important factors responsible for changes in the bacterial community of silages. Results confirmed the existence of a specific bacterial microbiome that was unique for each maturity and storage time. Variations in these factors also affected the fermentation quality through influencing the bacterial community.