The Decomposition of Formates by B. coli communis. 



461 



DESCRIPTION OF PLATES. 



1. Three days' growth in fresh homogenous plasma. 



2. Three days' growth in homogenous plasma three days old. 



3. Three days' growth in homogenous plasma ten days old. 



4. Three days' growth in fresh autogenous plasma. 



5. Five days' growth in fresh autogenous plasma. 



6. Five days' growth in fresh homogenous plasma. 



The Decomposition of Formates by Bacillus coli communis. 

 By Egerton Charles Grey, 1851 Exhibition Scholar. 



(Communicated by Dr. A. Harden, F.E.S. Received February 19, — Read 



March 26, 1914.) 



(From the Biochemical Department of the Lister Institute.) 



Many observations have been made on the variability of gas production by 

 intestinal bacteria under natural conditions (see Penfold (1911) and Arkwright 

 (1913), -where literature is quoted). 



Penfold has found that by artificial selection of Bacillus coli communis in 

 the presence of sodium chloroacetate, strains may be isolated which produce 

 no gas from glucose and gas in lessened amount from mannitol, although in 

 both cases acid is produced as with the normal organism. The writer has 

 also shown that by artificial selection of B. coli communis by the chloro- 

 acetate method of Penfold, various stages between the original gas-producing 

 and the selected non-gas-producing strain may be obtained, and the changes 

 have been found to be associated in part with the disappearance of the enzyme 

 which decomposes formic acid (1914). It was found that two kinds of 

 artificially selected strains could be produced from the original strain of 

 B. coli communis ; one unable to decompose formic acid, and the other still 

 able to bring about this decomposition provided glucose were present. 

 The artificially selected organism, which could not decompose formates 

 even in the presence of glucose, was likewise unable to produce gas 

 from mannitol, whereas the organism which still retained the power of 

 decomposing formates was also able to produce gas from mannitol, although 

 it produced this gas in an amount approximately equal to one-half of that 

 produced under the same conditions by the original B. coli communis from 

 which it was derived. It seemed, therefore, likely that by a closer study of 



