Antimicrobial and antibiofilm formation activities of chrysazin on bacillus species in vitro and in vivo using Thai silkworm model

Abstract

Bacillus species cause food poisoning, localized infections and systemic infections. They also can become more resistant to antibiotic by forming of biofilms. The aim of this study, therefore was to investigate antimicrobial and antibiofilm activities of chrysazin, a major bioactive compound in Xyris indica L. on Bacillus cereus and Bacillus subtilis using both in vitro studies and in vivo studies using Thai silkworm model. From broth microdilution method, we observed that B. cereus was more susceptible to chrysazin than B. subtilis with MIC value of 7.81 and 15.63 µg/ml, respectively. Furthermore, results from Time-Kill Assay indicated that chrysazin was bacteriostatic agent against both microorganisms. In addition chrysazin also exerted antibiofilm formation activity against both B. cereus and B. subtilis in a concentration-dependent manner with maximum % inhibition of 85.15 and 73.86, for B. cereus and B. subtilis, respectively at concentration 500 µg/ml. Chrysazin demonstrated antibacterial activity in Thai silkworm infection model on both B. cereus and B. subtilis with the maximum % survival of 60.33±0.33 and 50.67±0.33, respectively at concentration 1,000 µg/ml. In conclusion this study showed that chrysazin has its potential for developing as an antibacterial drug and antibiofilm agent against B. cereus and B. subtilis.