A gene for carotene cleavage required for pheromone biosynthesis and carotene regulation in the fungus Phycomyces blakesleeanus

Mating and sexual development in fungi are controlled by molecular mechanisms that are specific for each fungal group. Mating in Phycomyces blakesleeanus and other Mucorales requires pheromones derived from β-carotene. Phycomyces mutants in gene carS accumulate large amounts of β-carotene but do not enter the sexual process. We show that carS encodes a β-carotene-cleaving oxygenase that catalyzes the first step in the biosynthesis of a variety of apocarotenoids, including those that act as pheromones. Therefore carS mutants cannot stimulate their sexual partners, although they respond to them. CarS catalyzes the biosynthesis of a β-ring-containing apocarotenoid that inhibits the activity of the carotenogenic enzyme complex in vegetative cells and provides a feedback regulation for the β-carotene pathway. The carS gene product is a keystone in carotenogenesis and in sexual reproduction.     

产胡萝卜素酵母的筛选

从被油污染的土样和植物的落花中分离筛选出几株产胡萝卜素的酵母菌,其中从椰子油污染的土样中分离获得的菌株ＣＯＳ－５的胡萝卜素产量最高。ＣＯＳ－５菌株经鉴定为红酵母（Ｒｈｏｄｏｔｏｒｕｌａ ｓｐ．）ＣＯＳ－５。该菌株以蔗糖为碳源,添加桔子皮和盐酸硫胺素的培养基２８℃振荡培养９６ｈ,细胞生物量为２７．５ｍｇ干重／ｍｌ发酵液,胡萝卜素产量为１３．５５μｇ／ｍｌ发酵液。菌体胡萝卜素含量达４９２．７μｇ／ｇ干