EFFECTS OF CULTURE CONDITIONS ON Bacillus licheniformis KN12 ANTIFUNGAL ACTIVITY AGAINST Fusarium oxysporum AND Fusarium equiseti

Fusarium spp. are emerging fungal pathogens that cause Fusarium wilt in various domestic plants, leading to large economic losses worldwide. In order to find a safe and effective way in substitution of synthersized chemicals, many bacterial strains have been widely studied and applied on a variety of plant to control these fungal pathogens. In this study, the suitable culture conditions for synthesizing antifungal compounds produced by Bacillus licheniformis KN12 strain antagonizing Fusarium oxysporum and Fusarium equiseti were identified. The culture obtained after cultivation of this strain on Luria-Bertani broth with initial pH 7.0 at 37 °C, and 150 rpm for 15 hours was recorded to have the highest antifungal activity. The F. oxysporum and F. equiseti inhibitory activity of the culture supernatant was relatively heat-resistant (up to 90 °C). In addition, the inhibitory activity of the culture supernatant against F. oxysporum maintained at pH 5.0 - 10.0 while against F. equiseti was retained in wide pH spectrum 3.0 - 11.0. These results suggested that B. licheniformis KN12 could be a potential strain for futher studies and applications in controlling Fusarium diseases in sustainable agriculture.