Role of Bacillus tequilensis EA-CB0015 cells and lipopeptides in the biological control of black Sigatoka disease

Abstract

Black Sigatoka disease is a devastating fungal pathogen that affects banana crops worldwide and is caused by the ascomycete fungus Pseudocercospora fijiensis. In an effort to mitigate the environmental impacts of chemical fungicides, microbial biological control agents (MBCA) have been developed. However, a comprehensive understanding of the modes of action of these products are needed to enhance their efficacy under field conditions. Consequently, the functional role of different components of a Bacillus tequilensis EA-CB0015-based product was studied to understand their role in conferring protection to banana plants against the infection of P. fijiensis. Under this perspective, we evaluated the effect of B. tequilensis EA-CB0015 lipopetides on the severity of black Sigatoka disease, as well as the ability of the bacterial cells to colonize and produce lipopeptides on the leaf surface of banana plants (Musa AAA cv. Williams). Our work provides evidence that lipopetides significantly reduce the disease severity and that the bacterial cells colonize the leaf surface of banana plants inoculated with P. fijiensis during the first 48 h of incubation. Furthermore, we were able to detect an increased production of surfactins during colonization using mass spectrometry analysis. Altogether, our results suggest that the biological control strategies implemented by the MBCA product against P. fijiensis involves a direct interaction via antibiosis, as well as an indirect interaction via competition of nutrients and space.