Regulation of Carotenogenesis by Inorganic Phosphate in Blakeslea trispora

Increasing the inorganic phosphate concentration of the medium from 0.01% to 1% (w/v) resulted in 4.5-fold higher production of carotene in Blakeslea trispora. The pattern of β-carotene synthesis in B. trispora remained essentially the same in both high (1%) and low (0.01%) phosphate grown cultures. Higher concentrations of intracellular orthophosphate and lower activities of acid and alkaline phosphatase were found in the high phosphate grown cells as compared to the low phosphate grown cultures. The intracellular acid and alkaline phosphatase activities of B. trispora were competitively inhibited by inorganic phosphate. One or more forms of the acid and the alkaline phosphatases were apparently repressed during active carotenogenesis in the high phosphate grown B. trispora as compared to low phosphate grown cells. An inverse relationship was found between carotenogenesis and the intracellular phosphatase activities and it is suggested that inorganic phosphate concentration affects β-carotene synthesis in B. trispora by regulating the intracellular phosphatase levels in the culture.