Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Key Laboratory of Industrial Microbiology, National Engineering Laboratory for Industrial Enzymes, The College of Biotechnology, Tianjin University of Science and Technology, Tianjin, People's Republic of China.
J Ind Microbiol Biotechnol. 2014 Apr;41(4):701-9. doi: 10.1007/s10295-014-1409-4. Epub 2014 Feb 8.
Cadaverine (1,5-pentanediamine, diaminopentane), the desired raw material of bio-polyamides, is an important industrial chemical with a wide range of applications. Biosynthesis of cadaverine in Corynebacterium glutamicum has been a competitive way in place of petroleum-based chemical synthesis method. To date, the cadaverine exporter has not been found in C. glutamicum. In order to improve cadaverine secretion, the cadaverine-lysine antiporter CadB from Escherichia coli was studied in C. glutamicum. Fusion expression of cadB and green fluorescent protein (GFP) gene confirmed that CadB could express in the cell membrane of C. glutamicum. Co-expression of cadB and ldc from Hafnia alvei in C. glutamicum showed that the cadaverine secretion rate increased by 22 % and the yield of total cadaverine and extracellular cadaverine increased by 30 and 73 %, respectively. Moreover, the recombinant strain cultured at acid and neutral pH separately hardly had any difference in cadaverine concentrations. These results suggested that CadB could be expressed in the cell membrane of C. glutamicum and that recombinant CadB could improve cadaverine secretion and the yield of cadaverine. Moreover, the pH value did not affect the function of recombinant CadB. These results may be a promising metabolic engineering strategy for improving the yield of the desired product by enhancing its export out of the cell.
腐胺（1,5-戊二胺，二氨基戊烷）是生物聚酰胺的理想原料，是一种具有广泛应用的重要工业化学品。在谷氨酸棒杆菌中生物合成腐胺已经取代了基于石油的化学合成方法。迄今为止，尚未在谷氨酸棒杆菌中发现腐胺外排体。为了提高腐胺的分泌量，研究了来自大肠杆菌的腐胺-赖氨酸反向转运蛋白 CadB 在谷氨酸棒杆菌中的作用。CadB 与绿色荧光蛋白（GFP）基因的融合表达证实 CadB 可以在谷氨酸棒杆菌的细胞膜上表达。在谷氨酸棒杆菌中共表达 CadB 和来自产氨短杆菌的 ldc 基因后，发现腐胺的分泌速率提高了 22%，总腐胺和细胞外腐胺的产率分别提高了 30%和 73%。此外，在分别在酸性和中性 pH 下培养的重组菌中，腐胺浓度几乎没有差异。这些结果表明 CadB 可以在谷氨酸棒杆菌的细胞膜上表达，并且重组 CadB 可以提高腐胺的分泌量和产率。此外，pH 值不影响重组 CadB 的功能。这些结果可能为通过增强目标产物的外排来提高其产量的代谢工程策略提供了新的思路。
