Cyclic lipopeptides fengycins from marine bacterium Bacillus subtilis kill plant pathogenic fungus Magnaporthe grisea by inducing reactive oxygen species production and chromatin condensation.
Wednesday, 2018/07/11 | 08:14:26
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Appl Environ Microbiol. 2018 Jul 6. pii: AEM.00445-18. doi: 10.1128/AEM.00445-18. [Epub ahead of print] AbstractRice blast caused by phytopathogen Magnaporthe grisea poses a serious threat to the global food security and is difficult to control. Bacillus species have been extensively explored for the biological control of many fungal diseases. In the present study, marine bacterium Bacillus subtilis BS155 showed a strong antifungal activity against M. grisea The active metabolites were isolated and identified as cyclic lipopeptides (CLPs) of the fengycin family, named fengycin BS155, by the combination of high-performance liquid chromatography (HPLC), electrospray ionisation mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MS/MS). Analyses using scanning and transmission electron microscopy revealed that fengycin BS155 caused morphological changes in the plasma membrane and cell wall of M. grisea hyphae. Using comparative proteomic and biochemical assays, fengycin BS155 was demonstrated to reduce the mitochondrial membrane potential (MMP), induce bursts of reactive oxygen species (ROS) and down-regulate the expression level of ROS scavenging enzymes. Simultaneously, fengycin BS155 caused chromatin condensation in fungal hyphal cells, which led to the up-regulation of DNA repair-related proteins expression and the cleavage of poly (ADP-ribose) polymerase (PARP). Taken together, our results indicate that fengycin BS155 acts by inducing membrane damage and dysfunction of organelles, disruption of MMP, oxidative stress, and chromatin condensation, resulting in M. grisea hyphal cell death. Therefore, fengycin BS155 and its parent bacterium are very promising candidates for the biological control of M. grisea and the associated rice blast, and should be further investigated as such.Importance Rice (Oryza sativa L.) is the most important crop and a primary food source for more than half of the world's population. Notably, scientists in China have developed several types of rice that can be grown in seawater, avoiding the use of precious freshwater resource and potentially creating enough food for 200 million people. Plant-affecting fungus Magnaporthe grisea is the causal agent of rice blast disease, whereby biological rather than chemical control of this threatening disease is highly desirable. In this work, we discovered fengycin BS155, a cyclic lipopeptide material produced by marine bacterium Bacillus subtilis BS155, that showed strong activity against M. grisea Our results elucidate the mechanism of fengycin BS155-mediated M. grisea growth inhibition, and highlight the potential of B. subtilis BS155 as a biocontrol agent against M. grisea in rice cultivation under both fresh- and salt water conditions.
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