Survival and Germination ofBacillus clausiiUBBC07 Spores inin vitroHuman Gastrointestinal Tract Simulation Model and Evaluation of Clausin Production

Bacillus clausiiUBBC07 is a commercial spore probiotic known to reduce diarrhea in children and adults. In the present study, survival and germination of UBBC07 spores were investigated under fed and fasted conditions in Simulator of Human Intestinal Microbial Ecosystem. Besides this, lantibiotic production, purification, and characterization were performed. The agar plate analysis showed that spores were 100% tolerant to fed and fasted gastrointestinal tract (GIT) conditions. Simultaneously, flow cytometry revealed that at the end of small intestinal incubation, 120% (fed) and 133% (fasted) spores were in viable germinating state. The transformation of viable germinating spores into viable vegetative cells was observed at 3 h of incubation under fasted GIT conditions. In antimicrobial evaluation, UBBC07 produced low-molecular-weight (2107.94 Da) class I lantibiotic clausin. The presence oflanB,lanC, andlanDgenes confirms the clausin production. Clausin is stable at proteases (pepsin, proteinase K, and trypsin), temperature (up to 100 degrees C), and pH (up to 11). Furthermore, the antimicrobial activity toward Gram-positive bacteria includingClostridium difficileis advantageous. In conclusion,B. clausiiUBBC07 spore probiotic is capable of surviving and germinating underin vitroupper GIT conditions. The clausin production justifies strain applicability in diarrhea.