Inhibitory Effects of Bacillus Licheniformis Wj53a and Homofermentative Lactic Acid Bacteria on Clostridial Growth in Corn Silage

Abstract

This study reports on the effectiveness of silage additive based on consortium Lacticaseibacillus paracasei L1a and Bacillus licheniformis WJ53A in comparison with three homofermentative lactic acid bacteria (LAB) (Pediococcus acidilactici 12c, L. Lacticaseibacillus paracasei L1a, and L. plantarum S1aR). For this purpose, the antagonistic activity of these isolated LAB was tested. The impact of the isolated LAB on silage acidity, organic acid content, and dry matter of silage was also determined. The fungal and bacterial DNA load in the conserved silages was estimated using quantitative PCR and their effects on the quality category of silage were evaluated. The obtained results showed all inoculants being effective in ensiling of maize with the consortium (L1a + WJ53A), showing a high lactic acid content (94.51%, P<0.0001) in comparison to control (88.28%, P<0.0001). The consortium also showed a lower acetic acid (5.49% to 10%, P=0.0002) and absolutely no butyric acid in respect to control silage (0% to 1.64%, P<0.0001). The qPCR results presented an increase in the final LAB DNA concentration of silage conserved with consortium (0.002487 ng, P=0.0002) when compared to control (0.001127 ng, P=0.0002) but did differ from the inoculant of L1a (0.001790 ng, P=0.0219). Also, the final fungal DNA concentration showed the effectiveness of the consortium by the reduction of fungal DNA in comparison to control (0.00027 ng against 0.00106 ng, P=0.0007). The most interesting result is the inhibition of clostridia growth based on the qPCR analysis which showed a lower clostridial DNA in silage inoculated with the consortium (P<0.001) against all the inoculants used in this study. This research shows the advantage of ensilaging with a consortium of a homofermentative LAB and a Bacillus strain B. licheniformis WJ53A which reduces the risk of clostridial infections in livestock farming.