Inhibitory effects of Bacillus licheniformis BL06 on Phytophthora capsici in pepper by multiple modes of action

Phytophthora capsici is a pathogenic oomycete that affects pepper cultivation and other commercial products, causing serious economic losses. Here, Bacillus licheniformis strain BL06 effectively reduced pepper Phytophthora blight severity. BL06 suppressed P. capsici mycelium growth by 70% in dual culture tests and induced excessive branching and significant lysis of P. capsici hyphae. The BL06 bacterial culture also inhibited in vitro sporangia development in a dose-dependent manner. Moreover, BL06 inhibited motility and displayed lytic activities against zoospores of P. capsici in a dose- and time-dependent manner. Indeed, the P. capsici infectiousness was reduced in host tissue treated by BL06, which is possibly associated with its ability to inhibit zoospore germination and germ tube growth in host tissues. Collectively, our results demonstrate the utility B. licheniformis BL06 as a potential biocontrol agent for the management of Phytophthora blight of peppers.