Expression of Synechocystis sp. PCC6803 cyanophycin synthetase in Lactococcus lactis nisin-controlled gene expression system (NICE) and cyanophycin production

• Published in: Biochemical engineering journal 2013-09, Vol.78, p.114-119
• Main Authors: Tseng, Wen-Chi, Fang, Tsuei-Yun, Chang, Kai-Chun, Pan, Chorng-Liang
• Format: Article
• Language: English
• Subjects: arginine; aspartic acid; Biological and medical sciences; Biopolymer; Biotechnology; Culture condition; Cyanophycin; Fundamental and applied biological sciences. Psychology; gene expression; genes; GRAS substances; Lactic acid bacteria; Lactococcus lactis; Lactococcus lactis subsp. cremoris; nisin; Recombinant DNA; Synechocystis; Synechocystis sp. PCC 6803
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2013.02.009

► We established cyanophycin production by Lactococcus lactis. ► An addition of one glycine codon onto the cphA gene can enhance the specific yield. ► A high specific yield of 20% dry cell weight can be obtained. ► The cyanophycin existed mostly in the insoluble form with a low content of lysine. Cyanophycin is a natural source of polypetide consisting of aspartic acid as a backbone and arginine as its side chain. After the removal of arginine, the remaining poly-aspartate can be served in numerous industrial and biomedical applications. The synthesis of cyanophycin is catalyzed by cyanophycin synthetase. In this study, we used lactic acid bacteria to produce cyanophycin by nisin-controlled gene expression system (NICE). The cyanophycin synthetase gene cphA of Synechocystis sp. strain PCC6803 was cloned to the vector pNZ8149 followed by transformation into Lactococcus lactis subsp. cremoris NZ3900. The effects of nisin concentrations and the amounts of supplemented aspartic acid and arginine were examined for the production of cyanophycin. Alterations of the terminus of cphA gene were also conducted in an attempt to increase the yield of cyanophycin. An optimal cyanophycin production was noted under a culture condition of log phase induced at 250ng/mL nisin in M17L medium supplemented with 20mM arginine and 10mM aspartic acid. An insertion of glycine residue at the C terminus of cyanophycin synthetase resulted in a yield of 20% of dry cell weight, a 10-fold increase when compared with the wild type. The results showed that recombinant lactic acid bacteria, a GRAS system, could provide an alternative approach of producing cyanophycin suitable for agricultural and biomedical applications.