A polypeptide having the enzymatic activity of converting the 4-methylene group of a β-ionone compound into a keto group; a DNA containing the base sequence coding for the above polypeptide; another DNA which hybridizes with the above DNA and contains the base sequence coding for the above polypeptide; still another DNA which has been inserted into plasmid pHP51 and contains the base sequence coding for the above polypeptide; a recombinant vector containing the above DNA(s); a microbe having the above DNA(s) introduced thereinto; and a process for producing a ketocarotenoid which comprises culturing the above microbe in a medium and separating the formed ketocarotenoid from the product of culture. The introduction of the above DNAs as foreign genes into microbes, such as E. coli, followed by expression thereof makes it possible to impart to the microbes the capability of biosynthesis of astaxanthin, 4-ketozeaxanthin, canthaxanthin, echinenone and other ketocarotenoids. The use of such microbes makes it possible to mass-produce ketocarotenoids at reduced cost and labor.
                            具有将 β-酮化合物的 4-亚甲基转化为酮基的酶活性的
多肽;含有上述
多肽编码碱基序列的 DNA;与上述 DNA 杂交并含有上述
多肽编码碱基序列的另一种 DNA;已插入质粒 pHP51 并含有上述
多肽编码碱基序列的另一种 DNA;含有上述 DNA 的
重组载体;导入上述 DNA 的微
生物;以及生产酮
胡萝卜素的工艺,该工艺包括在
培养基中培养上述微
生物并从培养产物中分离形成的酮
胡萝卜素。将上述 DNA 作为外来
基因导入微
生物(如大肠杆菌),然后进行表达,可使微
生物具有
生物合成
虾青素、4-ketozeaxanthin、canthaxin、棘烯酮和其他类酮的能力。使用这些微
生物可以大量生产类酮
胡萝卜素,降低成本,减少劳动力。