Abstract:The stress tolerance and safety of Bacillus velezensis YE-1, an Aspergillus flavus antagonist, were analyzed herein to provide theoretical insights for further research and application of this strain. The survival rates of the strain at different temperatures (40, 50, 60, 70 and 80 ℃), NaCl mass fractions (1%, 2%, 3%, 4%, 5%, 6% and 7.5%), artificial gastric solution exposure (1, 2 and 3 h), and artificial intestinal solution exposure (2, 4 and 6 h) were determined. Additionally, the diameters of the inhibition zones corresponding to drug treatments were measured to assess the stress tolerance and drug sensitivity of the strain. The results showed that the survival rate of B. velezensis YE-1 is 33.60% after 20 min treatment at 80 ℃; 19.75% after 2 h treatment with 7.5% NaCl; 33.57% after 3 h treatment in artificial gastric fluid; 64.24% after 6 h treatment in artificial intestinal fluid. Moreover, it is sensitive to most drugs. This indicates that the strain has a certain degree of stress tolerance and drug sensitivity. Additionally, the in vivo safety of B. velezensis YE-1 was evaluated via murine oral gavage studies at three doses (107, 108 and 109 CFU/mL) in a volume of 20 mL/kg•bw. The results revealed that gavage for 14 days imposed no adverse effects on the behavior, body weight, food intake, biochemical indices, hematological indices, organ indices, or histopathology of the mice. In conclusion, Bacillus velezensis YE-1 has a certain degree of stress tolerance and acceptable safety, rendering it a promising candidate for further development and practical application.
