Biocontrol and plant growth promoting properties of Bacillus sp. BioSol021 grown on meat and dairy industry effluents

Abstract

The valorization of industrial waste streams generated in vast quantities is becoming an increa-singly prominent priority in line with the principles of circular economy. One potential avenue for utilizing food industry waste streams lies in the production of microbial agents with biocontrol and PGP (plant-growth promotion) properties. Bacillus species, given their broad spectrum of bioactive metabolites, exhibit significant potential in the production of such bioagents. The aim of this study was to investigate the circular economy approach by utilizing whey from dairy industry, meat processing wastewater and digestate obtained from biogas production using solid meat industry effluents, as potential bases for media used to cultivate Bacillus sp. BioSol021 and to investigate their biocontrol activity against pepper black spot causal agent, Xanthomonas euvesicatoria, as well as their PGP effects in the pepper seed germination phase. The highest antimicrobial activity, tested using the disc diffusion method, was observed in the whey-based cultivation broth sample after 96 hours of cultivation. Pepper seeds treated with cultivation broth of Bacillus sp. BioSol021 based on meat industry wastewater exhibited the best results in terms of germination rate (80%), root length (10.40 mm) and shoot length (6.20 mm). The results of this study confirm the suitability of whey, meat industry waste-water, and biogas production digestate as the potential cultivation media components for producing Bacillus-based biocontrol and PGP agents for a more sustainable agricultural practice.