A Method of Obtaining Pure Radioactive β-Carotene Using Phycomyces Blakesleeanus

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Abstract
SUMMARY A reliable method for producing and purifying radioactive β-carotene by an isolate of Phycomyces blakesleeanus in still culture is described in detail. Only a trace of carotene was produced during the early phase of rapid mycelial growth. Carotenogenesis became appreciable as the phase of rapid growth declined, and continued for 4 to 5 days after the production of mycelium nearly ceased. Conditions highly favorable for growth or sporulation were unfavorable for the production of β-carotene. The carotene content of the mycelium reached 0.3 to 0.35 percent after 8 to 9 days of incubation. A 4- to 7-day-old culture grown on 25 ml of medium utilized as much as 12.2 mg of potassium acetate daily. Less glucose was utilized by cultures receiving added acetate than was utilized by the controls. When labeled acetate was added on the fifth day, radioactive β-carotene was synthesized. About one C14 atom out of 240 supplied as labeled acetate was recovered in crystalline β-carotene.