Wilkinson D, Ward J M, Woodley J M
Department of Chemical and Biochemical Engineering, University College London, UK.
J Ind Microbiol. 1996 May;16(5):274-9. doi: 10.1007/BF01570034.
The use of whole cell biotransformations for single and multistep enzyme conversions is gaining widespread application. In this study the naphthalene dioxygenase nah A gene was transferred into Pseudomonas aeruginosa PAC 1R, Escherichia coli JM107 and Pseudomonas putida PpG 277. The effect of ethanol on these genetically engineered Gram-negative bacteria was studied by measurement of enzyme activity, stability and cell integrity. Ethanol has been used in biotransformations as a co-substrate carbon source for co-factor recycling and as a co-solvent increasing dissolved substrate and product levels. Ethanol increased the dissolved substrate (naphthalene) concentration slightly and dissolved product ((+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene) by approximately 30% at 4% (w/v) ethanol. Both P. aeruginosa PAC 1R and P. putida PpG 277 showed decreased activity with increasing ethanol concentration whilst E. coli enzyme activity increased with increasing ethanol concentration being comparable to that when glucose was used as a carbon source. This project highlighted the many factors involved in the selection of microbial hosts for whole cell biotransformation processes.
全细胞生物转化用于单步和多步酶促转化的应用正在广泛普及。在本研究中，萘双加氧酶nah A基因被转入铜绿假单胞菌PAC 1R、大肠杆菌JM107和恶臭假单胞菌PpG 277。通过测量酶活性、稳定性和细胞完整性，研究了乙醇对这些基因工程革兰氏阴性菌的影响。乙醇在生物转化中被用作共底物碳源以进行辅因子循环，以及用作共溶剂以提高溶解的底物和产物水平。在4%（w/v）乙醇浓度下，乙醇使溶解的底物（萘）浓度略有增加，使溶解的产物（(+)-顺式-(1R,2S)-二羟基-1,2-二氢萘）增加约30%。随着乙醇浓度增加，铜绿假单胞菌PAC 1R和恶臭假单胞菌PpG 277的活性均降低，而大肠杆菌的酶活性随乙醇浓度增加而升高，与使用葡萄糖作为碳源时相当。该项目突出了全细胞生物转化过程中微生物宿主选择所涉及的诸多因素。
