Probiotic Bacillus subtilis SB8 and edible coatings for sustainable fungal disease management in strawberry

Abstract

Agriculture faces the critical challenge of providing safe food while reducing post-harvest phytopathogens losses, exacerbated by climate change. Berries, prized for their taste and nutrition, confront economic hurdles due to fungal diseases, notably strawberries. Exploring ecological alternatives, like biopesticides with probiotic properties in synergic with edible coatings, has emerged as a novel strategy to address this challenge. Our aim was to isolate bacteria capable of serving dual roles: combating fungal diseases while also enhancing food safety for consumers potentially applicable in conjunction with edible coatings. Strawberries, blueberries, and raspberries were surface disinfected, obtaining 19 isolates on MRS medium. Among these, we predominantly isolated Bacillus species, along with lactic acid bacteria (LAB) and potential pathogens. Selected bacterial strains were tested against three major phytopathogens: Botrytis cinerea, Alternaria alternata, and Colletotrichum acutatum. Bacillus subtilis SB8, B. tequilensis SB4.3.1, and B. cabrialesii SB4.3 showed promising results. B. subtilis was particularly notable for its antagonistic effects and it’s recognized as Generally Recognized As Safe (GRAS). An in vivo assay using the SB8 strain, combined with an alginate-based edible coating, demonstrated a reduction in B. cinerea infection. Sequencing the SB8 genome (approximately 4.0 Mb) revealed genes responsible for antimicrobial compound production and probiotic traits. Our study highlights the potential of these strategies to enhance the safety and sustainability of strawberry production, providing a novel approach to combat fungal diseases and ensure the safety of these fruits.