Abstract

This study describes the effects of lactic acid bacteria (LAB) on photosynthetic performance and antioxidant metabolism in Solanum lycopersicum L. (tomato) plants. Two strains of previously isolated and characterized LAB, Enterococcus sp. BB3 and Lactobacillus sp. BB6, were used alone or in combination as inoculants of tomato plants under controlled conditions in a 30-day assay. At the end of the assay, the physiological parameters of the plants were studied, including chlorophyll fluorescence, net photosynthesis, lipid peroxidation, antioxidant activity, and the content of photosynthetic pigments, total phenols, and flavonoids. The results show that, both individually and combined, these strains improve all physiological parameters in S. lycopersicum plants, where BB3 and BB6 alone increase photochemical features such as Fv '/Fm '; Phi PSII, and ETR. P-n, g(s), and E were higher in all three treatments with LAB. Meanwhile, oxidative damage, measured as lipid peroxidation, significantly decreased (P < 0.05) in all bacterial treatments, especially in the combined assay (BB3+BB6) in comparison with the control assays. Finally, a significant increase (P < 0.05) in antioxidant activity was observed but not in total phenol and flavonoid content in tomato plants treated with bacteria. Conclusion. Our data suggest positive effects on physiological features in S. lycopersicum L. mainly related to the BB3 and BB6 strains of LAB and a reduction of oxidative damage and antioxidant metabolism, generally associated with combined treatments.