Genomics Analysis of Bacillus megaterium 1259 as a Probiotic and Its Effects on Performance in Lactating Dairy Cows

SIMPLE SUMMARY: Probiotics play a vital role in animal production. Bacillus megaterium 1259, as a novel bacterium, has been used as a probiotic in poultry feed. In this study, we analyzed the genome sequence and genetic characteristics of Bacillus megaterium 1259 in order to have a deep understanding of its genomics information. Moreover, the effects of Bacillus megaterium 1259 as a probiotic on lactating dairy cow performance were determined due to the different digestive systems of dairy cows from poultry. The results suggest that Bacillus megaterium 1259 can increase milk production and will not bring any side effects on blood metabolites in dairy cows. ABSTRACT: In this study, we isolated a novel bacterium, Bacillus megaterium 1259 (BM1259), from chicken manure. Whole-genome sequencing analysis showed that the BM1259 complete genome is composed of a 5,043,095 bp circular chromosome and three circular plasmids, and it encodes 5379 coding genes and 182 RNA genes. Among these genes, a series of nitrate assimilation-related genes and pathways were identified, implying a potential role of BM1259 in nitrate metabolism. In addition, 24 lactating Holstein dairy cows were randomly assigned to four groups that were fed a total mixed ration (TMR) diet only (C), a TMR diet supplemented with 5 g/day of BM1259 (T1), a TMR diet supplemented with 10 g/day of BM1259 (T2), or a TMR diet supplemented with 15 g/day of BM1259 (T3). The results showed that supplementing dairy cows with 15 g/day of BM1259 increased 4% fat-corrected milk production. The molar proportion of propionate (C3) was significantly higher in T2 than in C. The C2:C3 ratio of T3 was higher than those of C and T2. No negative effect of BM1259 on blood indicators was detected. This study demonstrates BM1259 can be applied as a potential probiotic to improve nitrogen utilization and milk production in lactating dairy cows.