Mechanism of photo-induced and antimycin A-induced carotenoid synthesis in mycobacterium marinum. Requirements for carotenogenesis and further evidence for protein synthesis following induction

Abstract

In dark-grown Mycobacterium marinum, carotenoid synthesis can be induced either with light or with antimycin A. In this study, optimal requirements for caroenoid production have been investigated. The optimal conditions are: 7–30 mM glycerol, depending upon type of induction; 3 mM (NH 4) 2SO 4 (or 1.5 mg/ml casein hydrolysate); 50 mM phosphate; and pH in the range of 8–10. In addition, O 2 is required for carcinogenesis. Para-chloromercuribenzoate and para-hydroxymercuribenzoate, known to mimic light for carotenoid production in Fusarium aquaeductuum, inhibit rather than stimulate carotenogenesis in M. marinum. Three types of evidence suggest that both light and antimycin A induce carotenoid production by inducing the de novo synthesis of proteins (carotenogenic enzymes). (a) Chloramphenicol and puromycin block carotenogenesis. (b) A 4-h lag period preceding actual carotenogenesis is indicative of other synthetic events. (c) A source of nitrogen is needed for carotenoid formation. Kinetics of protein synthesis show that induced protein synthesis continues for more than 20 h if bacteria are given continuous light (or given antimycin A). This is in contrast to only 4 h of protein synthesis in bacteria which are given an initial saturating dose of light and then are dark incubated. Because of this decreased protein synthesis, the latter group of bacteria synthesizes substantially lower amounts of carotenoids.