Long Xiufeng, Wang Denggang, Zou Yuqi, Tian Jiewei, Tian Yongqiang, Liao Xuepin
Department of Biomass and Leather Engineering, Sichuan University Chengdu 610065 PR China
Guangdong Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology Guangzhou 510006 PR China.
RSC Adv. 2019 Sep 17;9(50):29205-29216. doi: 10.1039/c9ra05163e. eCollection 2019 Sep 13.
The halophilic bacterial strain PT-20, isolated from saline alkali soil samples and identified as a member of the genus , exhibited a robust ability to degrade phenol under high salt conditions. It was determined that strain PT-20 was capable of degrading 1000 mg L phenol completely in the presence of 10% NaCl within 120 h. Under the optimal degradation conditions, pH 8.0, 3% NaCl and 30 °C, 1000 mg L phenol could be completely degraded in 48 h. Interestingly, the biodegradation rate of phenol was dramatically improved in the presence of glycine betaine. When glycine betaine was added, the time required to degrade 1000 mg L phenol completely was significantly reduced from 120 h to 72 h, and the corresponding average degradation rate increased from 8.43 to 14.28 mg L h with 10% NaCl. Furthermore, transcriptome analysis was performed to investigate the effects of phenol and glycine betaine on the transcriptional levels of strain PT-20. The results indicated that the addition of glycine betaine enhanced the resistance of cells to phenol, increased the growth rate of strain PT-20 and upregulated the expression of related enzyme genes. In addition, the results of enzyme activity assays indicated that strain PT-20 degraded phenol mainly through a meta-fission pathway.
从盐碱土样品中分离得到的嗜盐细菌菌株PT-20，经鉴定为某属的成员，在高盐条件下表现出强大的苯酚降解能力。经测定，菌株PT-20在10% NaCl存在的情况下，能够在120小时内完全降解1000 mg/L的苯酚。在最佳降解条件（pH 8.0、3% NaCl和30°C）下，1000 mg/L的苯酚可在48小时内完全降解。有趣的是，在甘氨酸甜菜碱存在的情况下，苯酚的生物降解速率显著提高。添加甘氨酸甜菜碱后，完全降解1000 mg/L苯酚所需的时间从120小时显著缩短至72小时，在10% NaCl条件下相应的平均降解速率从8.43 mg/(L·h)提高到14.28 mg/(L·h)。此外，进行了转录组分析以研究苯酚和甘氨酸甜菜碱对菌株PT-20转录水平的影响。结果表明，添加甘氨酸甜菜碱增强了细胞对苯酚的抗性，提高了菌株PT-20的生长速率，并上调了相关酶基因的表达。此外，酶活性测定结果表明菌株PT-20主要通过间位裂解途径降解苯酚。
