Bacillus paralicheniformis strain H12 from saline soil for the management of gray mold in cherry tomatoes

Fungal phytopathogens cause severe yield loss, endangering vital crops such as cherry tomatoes. This study was undertaken to investigate and identify Bacillus species that possess broad-spectrum antifungal activity, specifically, to select a biocontrol agent against gray mold disease caused by Botrytis cinerea affecting cherry tomato, and investigating its safety features (antibiotic resistance, hemolysis, and virulence genes). Out of 82 Bacillus strains isolated from different regions in Algeria, 41 strains exhibited antifungal activity, while 28 strains demonstrated broad-spectrum activity. In vitro studies showed that each isolate produced at least one lytic enzyme (chitinase, glucanase, amylase, protease, or lipase). The most promising strains were all classified within the Bacillus subtilis group based on 16 S rRNA sequencing. The biocontrol potential of B. paralicheniformis H12 strain, which exhibited the highest inhibition index against B. cinerea, was tested in vivo. The assays showed that H12 strain significantly decreased the gray mold decay in cherry tomatoes and resulted in less weight loss (weight loss rate 2.76%) compared to the control group (5.04%). The genome of H12 consisted of 4,283,563 bp, with 4,226 coding DNA sequences, and a GC content of 45.87%. Genome mining unveiled diverse biosynthetic gene clusters related to antimicrobial properties. Furthermore, H12 was categorized as non-hemolytic and sensitive to different antibiotic families. These findings highlight the potential of B. subtilis group species as a potential biocontrol agent. Specifically, they provide valuable insight into the genomic features of the B. paralicheniformis strain H12 from saline soil (sabkha) as a prospective candidate for agricultural application.