Antifungal activity of Musa phyllosphere Bacillus pumilus strain against Mycosphaerella fijiensis

Black leaf streak disease (BLSD; also known as black Sigatoka) caused by Mycosphaerella fijiensis Morelet is one of the main diseases affecting banana trees worldwide. Associated microorganisms in the phylloplane have been previously studied for their control. An exhaustive understanding of biocontrol mechanisms will potentiate the biological control agent. Therefore, strain Bacillus pumilus CCIBP-C5, isolated from banana leaves surface was evaluated for in vitro antagonism against M. fijiensis and the effect of culture filtrate on fungal growth and disease progress was determined. Bacterial cell and its diffused metabolites inhibited M. fijiensis growth. The culture filtrate of B. pumilus affected the mycelial growth, with antifungal effect on hyphal tip, membrane permeability and integrity. Also, a reduction of number of BLSD necrotic lesions and disease progression were found after application of the B. pumilus CCIBP-5 culture filtrate in banana plants. Results indicate that CCIBP-C5 has potential for biological control of BLSD.