Carotenoid-biosynthesis genes as a genetic marker for the purpose of gene cloning.

A cloning vector pSL775 (7.0 kb) was constructed using the carotenoid-biosynthesis genes of Erwinia herbicola Eho13 (ATCC 53489). This vector contained a ColE1 origin, an ampicillin resistant gene, and a total of 11 single cloning sites: Asp718, AvaI, BamHI, BanII, EcoRV, HindIII, KpnI, MluI, NcoI, NotI, and SmaI. Transforming the vector into an Escherichia coli strain could result in pink clones. On the other hand, insertion of a DNA fragment into one of these cloning sites resulted in nonpigmented clones. The color differential between the two types of colonies could be detected visually on agar medium after culturing the cells at 37 degrees C for 18 hours.