The biodesulfurization of dibenzothiophene (DBT) by growing and resting cells of Rhodococcus erythropolis PTCC 1767 was studied in this work. The effects of Tween 80 on cell growth and its DBT desulfurization ability were investigated in both aqueous and two-phase systems. The growth-supportive behavior of Tween 80 along with its role in increasing the DBT solubility provided an effective biocatalytic activity in the resting cells assay. The desulfurization capability was also dependent on the hydrocarbon fraction phase and the initial concentration of DBT. Three oil phase fractions of 25, 50, and 75%v/v were tested to evaluate the influence of oil phase presence on DBT desulfurization efficiency. A further decrease in desulfurization ability was occurred at higher oil phase ratios mainly due to a higher mass transfer limitation and lower DBT bioavailability. In the biphasic system, the increment of DBT desulfurization yield was followed by increasing DBT concentration up to 3.5 mM, and thereafter, the cessation of increasing trend occurred. Maximum specific production rate of 2-hydroxybiphenyl (2-HBP) with oil phase fraction of 25%v/v was obtained 0.0055 mmol g⁻¹ h⁻¹ at initial DBT and Tween 80 concentrations of 3.5 and 6 mM, respectively. Finally, kinetics of DBT desulfurization by growing cells in aqueous and biphasic systems were best fitted by the Haldane and Michaelis–Menten equations, respectively. The desulfurization activity of R. erythropolis was not repressed in the biphasic system for DBT concentration up to 7.13 mM, while product inhibition was observed at DBT concentration higher than 0.45 mM in the aqueous system.

中文翻译：

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在水性和双相系统中，红球菌PTCC 1767对DBT脱硫

红球红球菌生长和静止细胞对二苯并噻吩（DBT）的生物脱硫在这项工作中研究了PTCC 1767。在水相和两相系统中都研究了吐温80对细胞生长及其DBT脱硫能力的影响。Tween 80的生长支持行为及其在增加DBT溶解度中的作用在静止细胞测定中提供了有效的生物催化活性。脱硫能力还取决于烃馏分相和DBT的初始浓度。测试了25、50和75％v / v的三个油相馏分，以评估油相的存在对DBT脱硫效率的影响。在较高的油相比下，脱硫能力进一步下降，这主要是由于较高的传质限制和较低的DBT生物利用度。在双相系统中 DBT脱硫产量的增加之后，是将DBT浓度增加到3.5 mM，然后停止增加趋势。获得油相分数为25％v / v的2-羟基联苯（2-HBP）的最大比生产率0.0055 mmol g初始DBT和吐温80浓度分别为3.5和6 mM时为^-1  h ^-1。最后，分别在Haldane和Michaelis-Menten方程中最佳拟合了在水相和双相系统中生长的细胞对DBT脱硫的动力学。的脱硫活性R.红球菌在两相系统不压抑DBT浓度可达7.13毫米，而在DBT浓度下观察到的产物抑制高于0.45毫在含水系统中。