Probiotic characterization, safety assessment, and production performance of a novel probiotic strain of <i>Bacillus subtilis</i> SKB/2074 (MCC 0563) in broiler chickens

Probiotics are living microorganisms when administered in adequate amounts confer health benefits to the host. In the present study, a soil isolate was identified as <i>Bacillus subtilis</i> based on the 16S rRNA sequencing. In probiotic functional characterization (<i>in vitro</i>), <i>B. subtilis</i> SKB/2074 produced 10 different enzymes, was stable under simulated gastric conditions (pH 2.5/1-3 hr), bile salt (0.05-0.3% w/v), and temperature (40-90 °C) conditions. <i>B. subtilis</i> SKB/2074 cells were non-hemolytic, found susceptible to the 30 antibiotics, and showed antimicrobial activity against <i>Escherichia coli</i>, <i>Salmonella typhimurium</i>, and <i>Clostridium perfringens.</i> In <i>in vivo</i> studies, <i>B. subtilis</i> SKB/2074 demonstrated encouraging results to reverse <i>E. coli</i> and castor oil incited diarrhea in Wistar rats and Albino mice, respectively. Histopathological studies exhibited restoration of damaged mucosal epithelium cells and recovers veracity of goblet cells (colon). <i>B. subtilis</i> SKB/2074 exhibited immunomodulatory effects (increased immunoglobulins in blood and weight of spleen and thymus) and significant antioxidant activity (84.14%), reducing capacity and ascorbate auto-oxidation inhibition effect (95.13%). In poultry field studies, <i>B. subtilis</i> SKB/2074 significantly improved growth performance and lowered mortality rate in broiler chickens. Based on these preliminary scientific assessments <i>B. subtilis</i> SKB/2074 is likely to be used as potential probiotic and antidiarrheal agent in humans and animal healthcare.