Abstract: The present invention relates, in general, to a biotechnological method for production of (3S,3'S) astaxanthin. In particular, the present invention relates to a peptide having a .beta.-C-4-oxygenase activity; a DNA segment coding for this peptide; a RNA segments coding for this peptide; a recombinant DNA molecule comprising a vector and the DNA segment; a host cell or organism containing the above described recombinant DNA molecule or DNA segment; and to a method of biotechnologically producing (3S,3'S) astaxanthin or a food additive containing (3S,3'S) astaxanthin, using the host.