Streptomyces canus GLY-P2 degrades ferulic and p-hydroxybenzoic acids in soil and affects cucumber antioxidant enzyme activity and rhizosphere bacterial community

The present study was conducted to investigate the effectiveness of Streptomyces (GLY-P2) in degradation of ferulic acid (FA) and p-hydroxybenzonic acid (PHBA) in the rhizosphere of cucumbers by assaying the alteration of antioxidant enzymes activities and rhizospheric microbial community. GLY-P2 was isolated, identified as Streptomyces canus, and applied to cucumber-planted soil containing FA and PHBA. Optimal conditions for FA and PHBA degradation by GLY-P2 were 40 °C, pH 7, and 0.2 g l−1 mixture of FA and PHBA. During the degradation, vanillin, vanillic acid, and protocatechoic acid were metabolites; and activities of superoxide dismutase (SOD), catalase, ascorbate peroxidase (APX), and dehydroascorbate reductase in GLY-P2 were induced. When inoculated into cucumber-planted soil containing 220 μg g−1 mixture of FA and PHBA, GLY-P2 degraded FA and PHBA in soil, improved plant growth, and decreased malonaldehyde, superoxide radical, and hydrogen peroxide levels in leaves. GLY-P2 also enhanced activities of SOD, catalase, glutathione peroxidase, APX, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase, increased contents of ascorbate and glutathione, and elevated transcript levels of copper/zinc SOD, manganese SOD, catalase, and APX in leaves. Moreover, GLY-P2 changed soil bacterial richness, diversity, and community composition, and increased phosphatase, catalase, urease, and sucrase activities in rhizospheric soil. GLY-P2 mitigates FA and PHBA stress in cucumber by activating leaf antioxidant enzymes and affecting soil bacterial community.