Integrated omits approaches for deciphering antifungal metabolites produced by a novel Bacillus species, B. cabrialesii TE3T, against the spot blotch disease of wheat (Triticum turgidum L. subsp. durum)

Bipolaris sorokiniana is an important biotic constraint for global wheat production, causing spot blotch disease. In this work, we present a comprehensive characterization of the cell-free culture filtrate (CF) and precipitated fraction (PF) of Bacillus cabrialesii TE3(T) showing an effective inhibition of spot blotch. Our results indicated that CF produced by B. cabrialesii TE3(T) inhibits the growth of B. sorokiniana through stable metabolites (after auto-claving and proteinase K treatment). Antifungal metabolites in CF and PF were explored by an integrated genomic-metabolomic approach. Genome-mining revealed that strain TE3(T) contains the biosynthetic potential to produce wide spectrum antifungal (surfactin, fengycin, and rhizocticin A) and antibacterial metabolites (bacillaene, bacilysin, bacillibactin, and subtilosin A), and through bioactivity-guided LC-ESI-MS/MS approach we determined that a lipopeptide complex of surfactin and fengycin homologs was responsible for antifungal activity exhibited by B. cabrialesii TE3(T) against the studied phytopathogen. In addition, our results demonstrate that i) a lipopeptide complex inhibits B. sorokiniana by disrupting its cytoplasmatic membrane and ii) reduced spot blotch disease by 93 %. These findings show the potential application of metabolites produced by strain TE3(T) against B. sorokiniana and provide the first insight into antifungal metabolites produced by the novel Bacillus species, Bacillus cabrialesii.

Automated summary

The study demonstrated that a lipopeptide complex produced by Bacillus cabrialesii is capable of inhibiting the growth of Bipolaris sorokiniana by disrupting its cytoplasmatic membrane, reducing the incidence of spot blotch disease by up to 93%. It also revealed the potential application of metabolites from strain TE3(T) against B. sorokiniana and provided insight into the antifungal metabolites produced by the novel Bacillus species.