Effect of rhizosphere inoculation with Bacillus strains and phytopathogens on the contents of volatiles and human health-related compounds in tomato fruits

This study consisted of determining the effect of Bacillus strains inoculated alone or in combination with phytopathogenic fungi on the production of human health-related compounds and volatile organic compounds (VOCs) in tomato fruits. Seedlings were cultivated under greenhouse conditions and inoculated with B. amyloliquefaciens, B. methylotrophicus and B. subtilis alone or in combination with Alternaria solani, Fusarium oxysporum and Phytophthora infestans. Fully ripe fruits were harvested and evaluated for carotenoid, phenol and VOCs contents. Lycopene was the most abundant carotenoid (46.4-167.62 mu g/g), followed by beta-carotene and lutein. Fruits from plants inoculated with Bacillus had the highest carotenoid content In contrast, phytopathogens decreased the carotenoid contents, especially the lycopene content The content of total phenols ranged from 0.42 to 0.90 mg GAE/g. The content of these compounds increased 1.5-fold in fruits from plants inoculated with Bacillus strains, especially those treated with B. methylotrophicus, but the greatest increase (1.9-fold) was observed in plants inoculated with phytopathogens. Both Bacillus strains and pathogens increased the antioxidant capacity, with a 2.8-fold increase compared to the control. Thirty-two VOCs were identified in the tested tomatoes. The Bacillus strains caused an increase in the concentration of VOCs, which could be associated with an increase in fruit quality.

Automated summary

This study investigated the effect of Bacillus strains on the production of human health-related compounds and volatile organic compounds (VOCs) in tomato fruits. The results showed that Bacillus strains increased the carotenoid and phenol contents in tomatoes, while phytopathogens decreased these contents. Both Bacillus strains and pathogens increased the antioxidant capacity in tomatoes. The concentration of VOCs in tomatoes also increased when inoculated with Bacillus strains.