Genetic modification in Bacillus subtilis for production of C30 carotenoids

C30 carotenoids, which have shorter backbones than C40 carotenoids, are known to be produced in the pathogenic bacterium Staphylococcus aureus that causes opportunistic infection. The first committed enzyme in the C30 carotenoid synthetic pathway is dehydrosqualene synthase CrtM. CrtM converts farnesyl pyrophosphate to dehydrosqualene. Dehydrosqualene desaturase CrtN then converts dehydrosqualene to the yellow C30 carotenoid, 4,4'-diaponeurosporene. This chapter describes a method to synthesize C30 carotenoids in Bacillus subtilis, which is generally recognized as a safe (GRAS) organism. Introduction of S. aureus crtM and crtN genes into B. subtilis results in yellow pigmentation. The B. subtilis transformant accumulates two C30 carotenoids, 4,4'-diapolycopene and 4,4'-diaponeurosporene. Furthermore, together with crtMN, introduction of S. aureus crtP and crtQ genes, which encode mixed function oxidase and glycosyltransferase, respectively, donates the ability to produce glycosylated C30 carotenoic acid. Thus, carotenoid biosynthesis genes of S. aureus is applicable to genetically modify B. subtilis in order to construct a safe organism producing C30 carotenoids.