NUTRITION OF PARAMECIUM AURELIA, STOCK 299

SYNOPSIS. Paramecium aurelia, stock 299 (symbiote‐free) was cultivated in a synthetic medium consisting of amino acids, vitamins, purine and pyrimidine derivatives, fatty acids, stigmasterol, sodium acetate and salts. The medium supported the continued growth of this stock in serial subculture. Populations up to 17,000 organisms/ml were obtained in 9 or 10 days in the medium supplemented with a phospholipid. Synthetic 1‐oleoyl‐2‐stearoyl‐dl‐phosphatidyl serine, phosphatidyl ethanolamine, phosphatidyl inositol, phosphatidyl serine and cephalin were comparable in growth‐promoting activity. The nutritional need for each of the components of the medium was examined. The following were determined to be essential nutrilites for P. aurelia: arginine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, threonine, tryptophan, tyrosine, valine, folic acid, nicotinamide, calcium pantothenate, pyridoxal, riboflavin, thiamine, DL‐6‐thioctic acid, guanosine, uridine (or cytidine), oleic acid, stigmasterol, calcium and magnesium. Serine replaced glycine for growth in the presence of thymidine. In the absence of thymidine, comparatively high levels of folic acid were required for optimal growth. Sodium acetate did not replace DL‐6‐thioctic acid. Populations were reduced in the absence of the non‐essential amino acids, alanine, asparagine, aspartic acid and glutamic acid. These were restored to optimal levels by the addition of sodium acetate to the medium. Pyruvate was about as effective as acetate in this respect; glucose and certain other carbohydrates were not. Copyright © 1969, Wiley Blackwell. All rights reserved