Plipastatin is a shared good by Bacillus subtilis during combating Fusarium spp.

Abstract

Bacillus subtilis a Gram-positive soil dwelling bacterium known for its wide range of bioactive secondary metabolites. The lipopeptide plipastatin produced by most B. subtilis isolates have been shown to exhibit potent anti-fungal activity against plant pathogenic fungi. While the effect of these anti-fungal compounds are well studied in the context of biocontrol, much less is known of their role in the environment, which also harbor non-producing strains of these compounds. Fusarium species produce multiple antibacterial compounds resulting in dysbiosis of the plant-associated microbiome and inhibiting plant beneficial bacteria like B. subtilis. While plipastatin is expected to be important for survival of B. subtilis, not all isolates carry the biosynthetic gene cluster for plipastatin suggesting that the protective effect of plipastatin might be shared. In this study, we investigated the protective effect of plipastatin against Fusarium oxysporum in a co-culture using a producer and a non-producer isolate of plipastatin. We tested the survival of single and co-cultured strains under Fusarium challenge in liquid media and solid agar plates to dissect the influence of spatial structure. Our results highlights that plipastatin protects the non-producer strain in a density dependent manner.