二苯并噻吩(DBT)及其衍生物微生物脱硫的4S途径需要4个酶(DszA,DszB,DszC and DszD)参与催化。其中DBT单加氧酶(DszC or DBT-MO)和DBT-砜单加氧酶(DszA or DBTO2-MO)都是黄素依赖型氧化酶,它们的催化反应需要菌体中还原型的黄素单核苷酸(FMNH2),FMNH2由辅酶黄素还原酶(DszD)再生。因此,共表达DszA,DszB,DszC和DszD可以提高整个脱硫途径的速率。构建了两个不相容性表达载体pBADD和paN2并在大肠杆菌中实现了4个脱硫酶基因的共表达。DszA,DszB,DszC和DszD的可溶性蛋白表达量分别占菌体总蛋白质的7.6%,3.5%,3.1%和18%。共表达时的脱硫活性是单独用paN2表达时的5.4倍,并对工程菌休止细胞脱除模拟柴油中DBT的活性进行了研究。
Rhodococcus sp.DS-3 with the ability to selectively desulfurize dibenzothiophene and grow with the sulfur atom desulfurized was quantitatively characterized in batch cultures.The fermentation process for desulphurization by DS-3 was analyzed.The transformation of dibenzothiophene to 2-hydroxydiphenyl was 86.3% in BioStat C10-3 fermentor with aerating at 48 L·h -1 , constant pH 7.8,fermentation temperature 30℃ and stirring at 300 r·min -1 .The kinetic models of growth,substrate consumption and product generation were established.The optimal parameters were estimated and fitted to model software MATLAB.The results, which showed the actual values in 95% confidence interval, proved that these kinetic models fitted well and fundamentally reflected the regularity of dibenzothiophene desulphurization in the fermentor.
