Fig. 4
The genetic stability of the P. putida mutants transformed with the recombinant plasmid pSEVA434-Z02 containing the intact zeaxanthin biosynthetic pathway. a The physical map of the recombinant plasmid pSEVA434-Z02. b Detection of the zeaxanthin biosynthetic genes by PCR in the continuous passage cultures of the P. putida mutants. Top: detection of the fragment containing the idi-ispA-dxs gene. Bottom: detection of the fragment containing the crtE-crtI-crtB-crtY-crtZ gene. Symbols: M, DNA marker; 1st, the first generation subculture; 3rd, the third generation subculture; 10th, the tenth generation subculture; NC, the use of ddH2O as the template; PC, the use of pSEVA434-Z02 as the template. c Test for the capacity of the continuous passage cultures of the P. putida mutants to synthesize the yellow product zeaxanthin. The P. putida mutants transformed with the empty vector pSEVA434 were used as the negative controls. d HPLC analysis for zeaxanthin production by the mutant KTU-U13-Z02