Effect of Temperature and Preservation Period on the Viability of Lyophilized Bacillus subtilis

Objective: We sought to study the effect of temperature and preservation period on the viability of lyophilized Bacillus subtilis. Methods: Forty-five test tubes that contained suspension of B. subtilisATCC 6633 were incubated for 4 hours at37°Candwashedtwicebeforefreeze-drying.Next, thelyophilizedbacteriawereexposed to different temperatures (-20°C, 2-8°C, and 25°C) and storage periods (30 days, 120 days, and 240 days). Further, the lyophilizedbacteriawere evaluated for their viability using the Milesand Misramethod.Finally, the colony count of B.subtilisineach group was compared andanalyzed using the two-way ANOVA and the Tukey-test (post-hoc test).Results: The lyophilized B. subtilisshowed the viability of 93.3% (42/45) of test tubes. All of the lyophilized B.subtilisstored at -20°C for 30, 120, and 240 days remained viable while the bacteria stored at 2-8°C and 25°Cshowed the viability of 93.3% (14/15) and 86.6%, respectively. The lyophilized B. subtilisstored at three grouptemperatures and kept for 120 and 240 days showed a significant decline in their number over thecontrolgroup(p <0.05). Conclusion: In conclusion, the temperature and preservation period significantly affect the viability of the lyophilized B. subtilis.©2022iGlobal Research and PublishingFoundation. All rights reserved.