Influence of carbon and nitrogen sources on Flavobacteriumgrowth and zeaxanthin biosynthesis.

Growth and production of zeaxanthin by Flavobacterium sp were studied using different carbon and nitrogen sources in a chemically defined medium. The best growth was supported by sucrose, but glucose yielded similar carotenoid concentrations. Both asparagine and glutamine stimulated growth and pigment formation. Carotenoid production and glucose consumption increased as a function of asparagine concentration. In the presence of asparagine, high glucose concentrations decreased pigment production without affecting biomass formation. In the absence of glucose, asparagine could not support growth and zeaxanthin production. When compared to the effect of 55 mM glucose, 10 mM oxaloacetate increased growth and carotenoid production. Pyruvate and other intermediates of the citric acid cycle showed a similar stimulatory effect. The intermediates of glycolysis: glucose 6-phosphate and fructose 1,6-diphosphate did not support growth. These results suggest that Flavobacterium sp utilizes asparagine primarily as a nitrogen source for growth and production of zeaxanthin.