Researcher(s)
- Shelby Serrano, Animal Science, University of Delaware
Faculty Mentor(s)
- Tanya Gressley, Agriculture and Natural Resources, Animal Science, University of Delaware
Abstract
Lactic acid bacteria (LAB) are efficient silage inoculants, known to improve fermentation conditions and stability. In 2023, we conducted an experiment on alfalfa that was treated with water (CON) or with an inoculant (BA) containing Lentilactobacillus buchneri, Lactiplantibacillus plantarum, Lactococcus lactis at 300,000 cfu/g of fresh forage. 5 replicates of each sample were then packed into vacuum sealed bags and allowed to ensile for 2, 5, and 112 days. We found that BA inoculated samples had an improved ensiling with a more rapid change in pH and increased acids when compared to CON. Our objective was to evaluate the differences in microbial diversity, abundance, and species presence in fresh and ensiled samples. DNA was extracted from pooled sample pellets and the V4-V5 region of the 16S rRNA gene was amplified and sequenced using Illumina MiSeq. Microbiome analysis was done using QIIME2 and RStudio to determine microbial diversity and to identify and quantify the different species present. Results showed a significant effect on the BA treated samples. Treatment affected microbial a-diversity, observed species (P <0.01) and Shannon index (P <0.01) with BA displaying lower a-diversity when compared to CON and fresh samples. b-diversity metrics Bray-Curtis and unweighted UniFrac (PERMANOVA, P < 0.01; betadisper P < 0.05) displayed differences between treatment types. Weighted UniFrac showed less significant difference than the other indices (PERMANOVA, P<0.01). In terms of abundance, Lactobacillaceae and Lactiplantibacillus were increased in BA treated silages compared to CON, while more epiphytic LAB genera like Weisella and Levilactobacillus and protein-degrading Enterococcus were increased in CON compared to BA. These differences in diversity and abundance can help to explain the quick drop in pH of treated samples, and the difference in lactic acid concentrations that may have led to a more stable and successful silage.