Investigation of effective formulations of Bacillus velezensis BV9 and identification of metabolites produced by it for controlling Take-all disease of Wheat

Bacillus species promote plant growth and suppress phytopathogens by producing a wide range of bioactive metabolites. This study investigated the capacity of Bacillus velezensis BV9 to synthesize volatile organic compounds (VOCs) and evaluated the effectiveness of different encapsulation matrices for controlled delivery. BV9 cells were encapsulated using alginate (ALG), whey protein concentrate (WPC), and natural gums—zedo (ZG), bane (BG), and tragacanth (TG)—via both layer-by-layer and multilayer techniques. The encapsulation systems were characterized in vitro for moisture content, swelling behavior, bacterial viability, and release efficiency. Additionally, the biological performance of free versus encapsulated BV9 was compared in terms of survival, wheat growth promotion, and suppression of Gaeumannomyces graminis var. Tritici. Among the tested formulations, ALG-WPC-ZG exhibited the highest swelling capacity (123.33 %) and moisture content (75.82 %), along with the highest bacterial release efficiency (94.33 %). Antifungal metabolites extracted from BV9 culture filtrates were purified, and homologues of iturin were identified through chromatographic analyses. In greenhouse trials, encapsulated BV9 significantly enhanced wheat growth and provided superior disease suppression compared to free cells. This study demonstrates that biodegradable, low-cost encapsulation systems can serve as effective carriers for the sustained release of beneficial microbes. The developed system offers a promising alternative to chemical fertilizers, improving microbial stability and efficacy under agricultural conditions, and enhancing plant health and resistance to soilborne pathogens.