一株C_X-DBT脱硫菌的筛选及发酵条件优化

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

【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、MgCl_2、温度及p H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、NH_4Cl_2.0 g/L、MgCl_2 0.1 g/L、微量元素1.0 m L/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。

[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 16 S 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 NH_4Cl, 0.1 g/L of MgCl_2, 1 m L of metal solution, at p H 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.