Selection of lactic yeast producing glucosylceramide from cheese whey.

From 2150 isolates from raw milk and milk products, yeast strains were surveyed to produce glucosylceramide from cheese whey. Most of the 54 strains that had accumulated a detectable amount of glucosylceramide were identified as Kluyveromyces lactis var. lactis. The cells of K. lactis var. lactis strain M-11 derived from domestic raw milk accumulated glucosylceramide 2.5-fold higher than K. lactis var. lactis NBRC 1267, the reference strain selected from the culture collections. Strain M-16 of K. lactis var. lactis derived from the same origin was found to synthesize a considerable amount of steryl glucoside in addition to glucosylceramide. Sequence analysis of ribosomal DNA intergenic spacer two regions revealed that strains M-11 and M-16 were diverged from a type strain of K. lactis var. lactis in the same species.

Simultaneous production of sphingolipids and ethanol by Kluyveromyces thermotolerans.

Kluyveromyces thermotolerans strain NBRC 1674 was selected for the simultaneous production of sphingolipids and ethanol from beet molasses. The strain gradually synthesized ethanol with fermentation periods and attained a level slightly higher than that of the strain of Saccharomyces cerevisiae usually used for ethanol production. The sphingolipids accumulated in the cells were composed of almost equal amounts of free ceramides and glucosylceramides. The sphingoid bases and fatty acids of the two sphingolipids differed from each other and changed under aerobic and anaerobic growth conditions. Oxygen limitation may cause accumulation of sphinganine by inhibiting sphingolipid desaturases and enhance its proportion in both the sphingolipids.

Determination of glucosylceramide contents in crop tissues and by-products from their processing.

Glucosylceramides were surveyed in crop tissues and by-products from their processing. Apple pulp contained the highest amount (0.94 mg g(-1)) of glucosylceramide and relatively less sterylglucoside, which is the major contaminant of partially purified glucosylceramide. Glucosylceramide from apple pulp was principally composed of 2-hydroxypalmitic acid as the fatty acid, 4-hydroxy-cis-8-sphingenine as the sphingoid base, and glucose as the hexose, similar to those of commercial preparations isolated from rice bran or wheat germ. Apple pulp may be an alternative source for the commercial production of glucosylceramides.