Enzyme cocktail containing NADH regeneration system for efficient bioremediation of oil sludge contamination

• Published in: Chemosphere (Oxford) 2019-10, Vol.233, p.132-139
• Main Authors: Ji, Lei, Fu, Xiaowen, Wang, Mutian, Xu, Chang, Chen, Guanhong, Song, Fanyong, Guo, Shuhai, Zhang, Qiang
• Format: Article
• Language: English
• Subjects: Bioremediation; Enzyme cocktail; NADH regeneration system; Oil sludge
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2019.05.253

Oil sludge is one kind of toxic and persistent contamination to ecology system from petroleum industry. In order to recycle contaminated sands and reduce environmental impacts at a lower operating cost, enzyme cocktail 21/CbFDH including NADH regeneration system for oily sludge bioremediation was constructed for the first time. The intracellular enzymes of oil-degrading strain Acinetobacter calcoaceticus 21 were prepared and the formate dehydrogenase gene Cbfdh from Candida boidinii was cloned and functionally expressed in E.coli BL21 induced by lactose. The activity and stability of CbFDH was enhanced through self-induction medium optimization using Box-Behnken design. The CbFDH activity was 12.2 times increased and was only decreased 3.9% upon storage at 30 °C for 5 d. The CbFDH increased the degradation rate of oil in high concentration. For the sludge with 10% oil (w/w), the degradation rate achieved 35.6% after 12 h using enzyme 21/CbFDH with the protein ratio of 1:4. The results will provide novel perspectives for creation and operation of petroleum-degrading enzymes involving formate dehydrogenase with higher efficiency and lower cost comparing to current microbial strains or consortium. [Display omitted] •Expression of the formate dehydrogenase gene from C. boidinii induced by lactose.•Enhancement of enzyme CbFDH activity and stability through Box-Behnken optimization.•Preparation of the intracellular enzymes of oil-degrading strain A. calcoaceticus 21.•Construction of enzyme cocktail 21/CbFDH including NADH regeneration system.•Efficient bioremediation for oily sludge with enzyme 21/CbFDH at low cost.