Response of Bacillus sp. F26 to Different Reactive Oxygen Species Stress Characterized by Antioxidative Enzymes Synthesis

The oxidative response of Bacillus sp F26 to different forms of reactive oxygen species (ROS) stress including H2O2, O2σ υ π σ υ πand OH· was investigated using diverse generating source of ROS, which was characterized by the synthesis of antioxidative enzymes. It was seen that the responses of cells to oxidative stress are largely dependent on species, mode (shock and continual), and intensity of stress. Higher synthesis rate of catalase (CAT) is crucial for Bacillus sp F26 to resist H2O2 stress. The damages of H2O2 to cell is minor if CAT can efficiently decompose H2O2 entering into the cell, and furthermore, the response can stimulate cell growths and sugar consumption. Conversely, cell growth and synthesis of antioxidative enzymes are greatly inhibited when the intensity of H2O2 stress overwhelms the cell capability of clearing H2O2. Owing to the difference in mode and the effect on cells between O2σ υ π σ υ π and H2O2, higher synthesis rates of CAT and superoxide dismutase (SOD) could not guarantee cells to eliminate H2O2 and O2σ υ πσ υ πefficiently. Therefore, the toxicity to cells induced by intracellular O2σ υ π σ υ πis more severe than H2O2 stress. Unlike the responses to H2O2 and O2σ υ π σ υ π, OH· stress significantly inhibited cell growth and synthesis of antioxidative enzymes because OH· is the most active ROS. These results indicated that Bacillus sp F26 will show diverse biological behavior in response to H2O2, O2σ υ π υ π, and OH· of stress owing to the discrepancy in chemical property. To survive in oxidative stress, the cells will timely adjust their metabolism to adapt to new environment including regulating synthesis level of antioxidative enzymes, changing rates of cells growth and substrate consumption.