Identification and Functional Analysis of Carotenoid Biosynthetic Genes in the Extremely Radioresistant Bacterium Deinococcus radiodurans Genomes

To investigate the biosynthetic genes and the biological functions of carotenoids in the radioresistant mechanisms of the extremely radioresistant bacterium, Deinococcus radiodurans, two colorless mutants knocking out of the phytoene synthase (crtB) and phytoene desaturase (crtl) genes were constructed by PCR and in vivo homologous recombination. The carotenoids of this bacterium were extracted and analyzed by HPLC-MS technique. Comparative analysis of the sensitivities among the two colorless mutants and wild Rl showed that the two colorless mutants were more sensitive to ionizing radiation (IR) and hydrogen peroxide, indicating that the deletion of crtB and crtl genes made the mutants unable to biosynthesize the crucial intermediate lycopene and series of downstreaming carotenoids. This study has provided a new and direct evidence to explore the biosynthesis genes of carotenoids and their biological functions for the radioresistant mechanisms in the extremely radioresistant bacterium D. radiodurans.