Physiological and biochemical characteristics of two antioxidant bacteria in desert soil

Abstract:

[Background] Microorganisms are frequently subjected to multiple stresses in deserts, including drought, high temperatures and UV radiation. These natural stressors make it easy for desert soil microorganisms to accumulate numerous superoxide ions and peroxides inside and outside their bodies, inhibiting their growth or directly causing death. [Objective] Desert soil bacteria exhibit antioxidant properties in order to adapt to the desert environment. As an important part of the desert ecosystem, the research on its antioxidant properties provides the scientific and technical bases for the development of antioxidant resources in desert areas, as well as the antioxidant mechanism of desert microbes. [Methods] We used desert soil bacteria as the research object to obtain two bacteria with strong antioxidant activity by hydrogen peroxide: Planomicrobium okeanokoites AX6 and Kocuria marina KD4. The antioxidant physiological and biochemical characteristics of bacteria in desert soil was explored by its growth curve under hydrogen peroxide, cell damage, antioxidant enzyme activities and free radical scavenging ability. [Results] The content of malondialdehyde in the cells of the two strains of bacteria in low concentration of hydrogen peroxide was significantly lower than that in negative control Escherichia coli. The glutathione peroxidase activity of strain AX6 was higher at 108.33 U/mL in 1.5 mmol/L hydrogen peroxide, meanwhile the scavenging ability of DPPH and superoxide anion radical was higher; while the catalase activity of strain KD4 increased to 1.16 U/mL in 3 mmol/L hydrogen peroxide was significantly higher than the positive control Deinococcus radiodurans, as well as the ability to scavenge hydroxyl radicals was higher. [Conclusion] There are large differences in the active antioxidant enzyme and free radical scavenging ability of bacteria in different desert soils, indicating the diversity of microbial antioxidant processes in desert soils.