一株CX-DBT脱硫菌的筛选及发酵条件优化

Isolation of a CX-DBT desulfurizing strain and optimization of its fermentation conditions

摘要:

【目的】从大型工业油田石油污染土样中分离鉴定一株能专一性脱除CX-DBT的脱硫菌株，分析其对CX-DBT的脱硫途径，并确定菌体最优发酵条件。【方法】以二苯并噻吩(DBT)为唯一硫源底物，多次富集并分离可代谢CX-DBT菌株，通过形态学、生理生化实验及16S rRNA基因序列分析对筛选菌株JDZX13进行鉴定。采用GC-MS鉴定菌株对CX-DBT的代谢产物，确定其相应的脱硫途径。通过单因素发酵实验确定最佳碳源、氮源、微量元素、MgCl2、温度及pH的水平范围，并采用正交实验进一步优化。【结果】该菌株鉴定为戈登氏菌属，命名为戈登氏菌JDZX13 (KP993297)，其CX-DBT代谢途径为“4S途径”。最佳发酵条件为：蔗糖15.0 g/L、NH4Cl 2.0 g/L、MgCl2 0.1 g/L、微量元素1.0 mL/L、pH 7.0、温度35 °C。【结论】获得一株通过“4S途径”代谢CX-DBT的脱硫菌株JDZX13，经过进一步优化实验，强化了菌株的生长和脱硫能力，该研究结果对石油生物脱硫技术的开发具有重要参考意义。

Abstract:

[Objective] The objective of this study is to isolate and identify a novel bacterial strain capable of selectively desulfurizing CX-DBT, and then to determine its desulfurizing pathway and optimize the culture condition. [Methods] CX-DBT was used as the sole sulfur resource to enrich the bacterial cultures, and then GC-MS was used to determine CX-DBT desulfurizing pathway by analyzing the metabolic productions. The new culture, strain JDZX13, was identified based on the morphological, physiological and biochemical properties, and 16S rRNA gene sequence profiles. Single factor test and orthogonal design method were performed to determine the optimal biodesulfurizaio conditions. [Results] The new strain JDZX13 belonged to Gordonia sp. and named as Gordonia sp. JDZX13 (KP993297), which could selectively desulfurize CX-DBT by “4S pathway”. The optimum operating conditions were found as 15 g/L of sucrose, 2 g/L of NH4Cl, 0.1 g/L of MgCl2, 1 mL of metal solution, at pH 7.0 and 35 °C. [Conclusion] A bacterial strain JDZX13 was successfully isolated and identified with the utilization of CX-DBT by “4S pathway”. After a serial optimizations, the cell growth and desulfurizing capability were further enhanced. This result would be an important reference for further exploring the petroleum biodesulfurization technology.