PRODUCTION OF SOPHOROSE LIPID BY CANDIDA (TORULOPSIS) APICOLA GROWN ON GLUCOSE

The production of extracellular sophorose lipid by Candida apicola IME T 43747 was studied after growth on glucose as sole carbon source. In the presence of citrate and after 120 h of cultivation, the microcryst alline lactonic sophorose lipid started to appear in the medium. The l ipid was shown to accumulate in the cell wall and only a minor part wa s liberated into the medium. By means of NMR studies it was shown that the cell wall-bound and the liberated lactonic sophorose lipid were i dentical and had a hydroxy DELTA8-hexadecenoic acid backbone. Biotrans formation of D-[1-C-13]glucose revealed that in glucose-grown cells gl ucose was degraded to trioses which were rearranged and flow backward via the gluconeogenic pathway into the glycolipid as documented by scr ambling of the C-13 label from the C-1 position into the D-[6-C-13]glu cose of sophorose. A further part of the trioses was used for de novo synthesis of the glycolipid fatty acid moiety via acetyl-CoA. By use o f a mixed substrate, i.e., glucose and hexadecane, part of the glucose added was directly incorporated into the carbohydrate moiety of the l ipid. These results are discussed in terms of the physiological signif icance of the sophorose lipid to act as extracellular carbon storage m aterial.