标题：Influence of the culturе conditions and the composition of culture medium on the antimicrobial properties of Bacillus subtilis strain 46/H1 against some filamentous fungi
摘要：Antibacterial and antifungal activities are characteristic features of many representatives of the genus Bacillus, in particular of the non-pathogenic species Bacillus subtilis. By using the classical agar-well diffusion method, we investigated the influence of the culture conditions and the composition of the culture medium on the antimicrobial activity of Bacillus subtilis strain 46/H1 against the filamentous fungi Fusarium oxysporum and Aspergillus flavus. The fungal suspensions were preliminarily inoculated in the agar media, whereas the cell-free supernatant, the cell biomass and the culture liquid of B. subtilis 46/H1 were pipetted into the wells. The influence of the cultural conditions on the inhibitory activity of B. subtilis 46/H1 was determined by cultivation in agar media with pH ranging between 5.0 and 8.0, at temperature 25оС and 30оС. The influence of the composition of culture medium on the inhibitory activity of B. subtilis 46/H1 was determined by changing the carbon and nitrogen sources. After 72 hours of incubation, the antimicrobial effect was determined by measuring the diameter of the zones of inhibition around the wells. The antimicrobial activity of B. subtilis 46/H1 against both fungal species was higher at temperature of cultivation 30оС. The change of the carbon and nitrogen sources in the standard culture medium led to an increase in the inhibitory effect, which was stronger against the fungus Fusarium oxysporum and almost insignificant against the second test-microorganism - Aspergillus flavus. In addition, the antifugal activity against Fusarium oxysporum was higher after changing the nitrogen source than after the change of the carbon source
