Studies in Fat Metabolism of Timothy Grass Bacillus. 279- 



acetic acid is added to a glucose medium (fig. 2 — 4 and 5) ; the added acetic 

 acid does not affect the nitrogen synthesised (0 - 018 grm. in both cases), whilst 

 the ratio of lipoids to nitrogen rises from T58 to 234. 



It seemed possible that this result might not be due specifically to the 

 acetic acid, but might be caused by the greater concentration of organic food 

 stuff in the medium. Experiments made on 068 per cent, and T4 per cent, 

 of lactic acid (fig. 2 — 1 and 2), and on 1-0 per cent, and 2 - per cent, of 

 glucose (fig. 2 — 6 and 7), show that this is not so. Increased concentration 

 of food in each case results in an increased production both of synthesised 

 protein and of lipoid material, i.e., increased general growth. The production 

 of protein is favoured rather more than that of fat, as is shown by the ratio 

 of lipoids to nitrogen. 



The inability to use acetic acid in the absence of carbohydrate or lactic 

 acid forms at first sight an analogy to the inability of the higher animals to 

 use fat in the absence of a minimum of carbohydrate. From this analogy, 

 the authors were led to grow the bacillus on the sodium salts of propionic and 

 butyric acids. Growth on both these proceeded readily in a manner com- 

 parable to growth on lactate and on glucose. The problem therefore appears 

 to be one of some complexity. A detailed study of the growth of this 

 organism on various simple straight-chain compounds is in progress, and will 

 form the subject of a later communication. 



Summary. 



The growth of the Timothy grass bacillus on a medium consisting of 

 inorganic salts, including ammonia as the sole source of nitrogen, glucose, and 

 sodium acetate, was followed in detail. The formation of protein nitrogen and 

 fat (a phosphatide and a non-phosphatide fraction) were followed stage by 

 stage, and correlated with the disappearance of glucose and acetate from the 

 medium. Attempts were made to isolate intermediate decomposition products 

 of glucose, but none were found. 



The growth of the organism on possible intermediate products of the break- 

 down of glucose was then studied. The growth on lactic acid (as lactate) was 

 very similar to that on glucose alone. The lactic acid could be completely 

 utilised and the formation of protein and fat resembled that on a glucose 

 medium. Growth on acetic acid (present as sodium acetate) was negligible in 

 amount, and the acetic acid was not attacked by the organism. A modified 

 method of estimating acetic acid is described. Growth on acetic and lactic 

 acid (acetate and lactate) showed that the presence of lactic acid enabled 

 the organism to utilise the acetic acid. Glucose also enabled the organism 

 to utilise the acetic acid. 



