Spheroplast fusions of Phaffia rhodozyma cells

A biologically pure culture of a stable fusion strain of Phaffia rhodozyma which produces in the range of from about 1430 .mu.g/g to about 1160 .mu.g/g of astaxanthin, and from about 2350 .mu.g/g to about 2950 .mu.g/g of total carotenoids and provides a yield of at least 24 percent on a dry cell weight basis when cultivated under suitable growth conditions in a shake flask with a productivity of in the range of from about 4500 .mu.g/l to about 8600 .mu.g/l based on a 5 day shake flask assay wherein the strain is cultivated under suitable conditions to facilitate near optimum growth of said strain.