Contribution of Bacillus cereus ERBP in ozone detoxification by Zamioculcas zamiifolia plants: Effect of ascorbate peroxidase, catalase and total flavonoid contents for ozone detoxification.

Eighteen plant species were screened for ozone (O₃) removal in a continuous system. Zamioculcas zamiifolia had the highest O₃ removal efficiency. To enhance O₃ removal by Z. zamiifolia, adding a compatible endophytic bacteria, Bacillus cereus ERBP into Z. zamiifolia was studied. After operating under an O₃ continuous system (150-250 ppb) at a flow rate of 0.3 L min^-1 for 80 h, inoculated plants (74%) exhibited higher O₃ removal efficiency than non-inoculated ones (53%). In addition, after O₃ exposure (80 h), the population of B. cereus ERBP in inoculated plants was significantly increased in both shoots approximately 35 folds and leaves 13 folds compared to inoculated plants without O₃ exposure. The results also showed that B. cereus ERBP had the ability to protect Z. zamiifolia against O₃ stress conditions. The increase in B. cereus ERBP populations was attributed to the significant increase in ascorbate peroxidase (APX) and catalase (CAT) activity. In addition, increasing B. cereus ERBP populations led to raise total flavonoid contents which is one of antioxidant compounds. Increasing APX, CAT activities, and total flavonoid contents can enhance O₃ detoxification in plant tissues. The mechanism of B. cereus ERBP for enhancing O₃ phytoremediation was proposed in this study. The results suggested that B. cereus ERBP was a potential tool for alleviating O₃ stress on Z. zamiifolia and enhancing O₃ phytoremediation efficiency.