Spray-drying process as a suitable tool for the formulation of Bacillus velezensis RC218, a proved biocontrol agent to reduce Fusarium Head Blight and deoxynivalenol accumulation in wheat

Abstract

Fusarium Head Blight is a worldwide disease affecting small graincereals. Among the different management strategies, biocontrolis an environmentally-friendly approach to counteract thisdisease. Biocontrol effectiveness of Bacillus velezensis RC218 wasdemonstrated under greenhouse and field trials, but formulationconditions were not specified. Bacillus velezensis RC218 was grownon a sucrose and yeast extract basal medium (control) and in thesame medium osmotically modified with NaCl to reach a 0.98 and0.97 aW for physiological improvement. Before spray-dryingprocess, MgSO4 (10% w/v) was added to the cells as a protectiveagent. Water, phosphate buffer and skimmed milk (10% w/v) wereevaluated as rehydration agents. Shelf-life of the product wasevaluated during 180 days at different storage temperatures (4°Cand 25°C). The viability of control cells after the drying processdecreased from 3.2 × 108 to 1.12 × 106 colony forming units pergram of dry weight (cfu/g dry w), meanwhile cells grown instressed media retained a viability of 5 × 106 cfu/g dry w. Waterand phosphate buffer resulted in the best rehydration agents.After 180 days, the best storing condition was observed for cellsgrown in NaCl at 0.97 aW and stored at 4°C, =4 × 106 cfu/g dry w,80% of the initial viability. Spray drying was found to be a goodmethod for conserving long term shelf-life of B. velezensis RC218dried cells.