荒漠土壤中两株抗氧化细菌的抗氧化生理生化特征

Physiological and biochemical characteristics of two antioxidant bacteria in desert soil

摘要:

【背景】微生物在荒漠生态系统中经常面临多重胁迫，包括干旱、高温、UV辐射，这些环境胁迫使得荒漠土壤微生物极易在体内外积累大量的超氧离子或过氧化物，抑制其生长或者直接造成死亡。【目的】荒漠土壤细菌为适应荒漠环境表现出抗氧化特性，作为荒漠生态系统重要组成部分，对其抗氧化特性的研究为荒漠地区抗氧化资源的开发提供科学依据和技术基础，也对荒漠微生物抗氧化机制的挖掘奠定了基础。【方法】利用过氧化氢氧化筛选出两株具有强抗氧化性的荒漠土壤细菌：海床动性微菌AX6 (Planomicrobium okeanokoites AX6)和海洋考克氏菌KD4 (Kocuria marina KD4)，通过测定其在过氧化氢条件下的生长曲线、细胞受损程度、抗氧化酶活性以及自由基清除能力，探究荒漠土壤微生物的抗氧化生理生化特征。【结果】两株细菌在低浓度过氧化氢中细胞丙二醛含量显著低于阴性对照大肠杆菌，在1.5 mmol/L过氧化氢中菌株AX6的谷胱甘肽过氧化物酶活性可达108.33 U/mL，同时DPPH、超氧阴离子自由基的清除能力显著升高；此外，在3 mmol/L过氧化氢中菌株KD4的过氧化氢酶活性升高至1.16 U/mL，显著高于阳性对照耐辐射球菌，羟自由基的清除能力也显著升高。【结论】不同荒漠土壤细菌的活性抗氧化酶种类、自由基清除能力存在较大差异，表明荒漠土壤微生物抗氧化过程的多样性。

关键词:荒漠土壤细菌，抗氧化，抗氧化酶，自由基清除能力

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.

Key words:Bacteria in desert soils, Antioxidant, Antioxidant enzyme, Free radical scavenging ability