506.    ---------------.  [CHEMICAL AND ENGINEERING NEWS.]  New Sources of Fats Sought in Germany.  Vol. 23, 1945, p. 1884.

                 The rapidly developing synthesis of hydrocarbons with fatty acids in the last 10 yr. (directly from CO₂ and H₂, or from hydrocarbons) suggested that the synthesis of fats (through esterifying fatty acids with glycerol) could soon be attempted on a large scale.  In practice, however, it became apparent that the road from the fatty acid to an edible fat is extremely complicated and expensive.  This is the reason why direct synthesis has not been taken up on a large technical scale.  Synthetic fat is used in U-boats, however, because it never gets rancid.  Actually Imhausen synthesis furnished a high-quality edible fat.  Because of the above-mentioned unsatisfactory aspects of a total fat synthesis from CO₂ and H₂ by ester formation, recourse was made to biochemical methods.  In this field fundamental progress was made.  Some researchers succeeded in growing fat-producing fungi (yeasts, fusaria), on entirely synthetic mediums.  The source of C for this synthesis is sugar (also pentose).  With this method it is easy to obtain fats from timber by way of sugar.  After approximately 48 hr. these fungi contain 15% of the original sugar supply in form of fat, which is suitable for human consumption.  In addition, approximately 15% protein is formed.  The necessary N₂ is derived from ammonium salts, nitrates, urea, amides, or easily synthesized amino acids.