We previously identified a new Bacillus sporothermodurans strain, TM-I-3, which produces volatile compounds that show potent inhibitory activity against certain types of fungi, including Aspergillus fumigatus and Cladosporium cladosporioides. Non-contact antifungals derived from this bacterium may provide multidirectional inhibition and may be useful in disease prevention. This study is aimed at identifying the stage of fungal growth that is inhibited by TM-I-3 to elucidate the mechanism of its contact-independent antifungal activity. We evaluated mycelial growth and the gross fungal colony areas after 7 days in each experimental group varying the time in the proximity of TM-I-3 for 24 hours each. The fungal growth inhibition assay showed that TM-I-3 inhibited spore germination: the lag phase in the sigmoid growth curve. The present study demonstrated that TM-I-3 might be an effective fungistatic agent against pathogenic and allergenic fungi.
Keywords: Bacillus; antifungal; fungistatic; volatile compounds.