一株对羟基苯甲酸降解菌的降解条件优化及缓解黄瓜根际对羟基苯甲酸胁迫效应

Optimization of degradation conditions and mitigation the stress effect of p-hydroxybenzoic acid in cucumber rhizosphere by a strain of p-hydroxybenzoic acid degrading bacteria

摘要:

植物根系分泌的自毒物质如对羟基苯甲酸(p-hydroxybenzoic acid, PHBA)等酚酸类物质是造成植物连作障碍的主要因子。【目的】获得对羟基苯甲酸降解菌并提高该降解菌的降解效率。【方法】采用筛选培养基和无机盐培养基，分离到1株PHBA降解菌株，经鉴定为橙色微杆菌(Microbacterium aurantiacum)。利用单因素试验及响应面方法对PHBA初始含量、培养温度、pH及氮源等影响菌株降解因素进行了优化。【结果】该菌株在PHBA含量为0.4 g/L，温度为30 ℃，pH值为8.0，氮源为硫酸铵时降解率最高，最佳降解条件为温度30.2 ℃，pH值8.3，PHBA浓度0.18 g/L，降解率达到100%。结合盆栽试验及高效液相色谱法得到该菌株能够有效缓解黄瓜根际PHBA胁迫效应。【结论】本研究筛选得到的菌株橙色微杆菌具有较高的PHBA降解能力，具有应用于连作障碍的潜在价值。

Abstract:

Phenolic acids autotoxic substances secreted by plant roots, such as p-hydroxybenzoic acid (PHBA), are the main factors causing continuous cropping obstacles in plants. [Objective] In order to obtain PHBA degrading bacteria and improve its degradation efficiency. [Methods] a PHBA-degrading strain was isolated by screening medium and inorganic salt medium, and it was identified as Microbacterium aurantiacum. The initial content of PHBA, culture temperature, pH and nitrogen source were optimized by single factor experiment and response surface methodology. [Results] The highest degradation rate was obtained when the PHBA content was 0.4 g/L, the temperature was 30 ℃, the pH was 8.0, and the nitrogen source was ammonium sulfate. The optimal degradation conditions were temperature 30.2 ℃, pH 8.3, and PHBA concentration 0.18 g/L, and the degradation rate reached 100%. Combined with pot experiments and high performance liquid chromatography, the results showed that the strain could effectively mitigate the PHBA stress effect in cucumber rhizosphere. [Conclusion] The strain of Microbacterium aurantiacum screened in this study has a high ability to degrade PHBA, and has the potential value in continuous cropping obstacles.