MICROBIAL METABOLISM AND ITS INDUSTRIAL IMPLICATIONS 



certain conditions may proceed less far, thus quite unexpectedly giving 

 rise to the formation of the new C-C bond as present in acetic acid 

 (Table VIII). The American investigator Barker has since shown 

 that this type of carbon dioxide hydrogenation is encountered in 

 several other dissimilation processes. Amongst others, he found that 

 this holds in the acetic acid fermentation of glucose discovered by 

 Fontaine and co-workers in which in principle a glucose molecule is 

 converted into three molecules of acetic acid. This yield will incur the 

 jealousy of the vinegar manufacturers, who, passing the intermediary 

 step of alcoholic fermentation, can never get more than two molecules 

 out of one molecule of glucose. 



Finally, I should like to draw your attention to the curious fermenta- 

 tion in which carbon monoxide acts as a substrate. In my laboratory, 

 Schnellen brought definite proof that certain methane-producing 

 bacteria could bring about the following startling reactions : 

 4CO +4H 2 -> 4C0 2 +4H 2 

 C0 2 +4H 2 -> CH 4 + 2 H 2 



4 CO+2H 2 0-> CH 4 +3C0 2 



In view of the highly poisonous character of carbon monoxide for so 

 many forms of life, it is certainly a remarkable biochemical 'stunt' that 

 Methanosarcina barkeri in an aqueous medium in contact with a gas 

 phase containing 100 per cent carbon monoxide will convert this gas 

 into a mixture of carbon dioxide and methane! 



In illuminating-gas plants, partly depending on production of 

 water gas, this conversion may well occur when gas holders of the wet 

 type are used. 



The examples given should have sufficed to establish the conviction 

 that microbial life in its protean variety is constantly lying in wait for 

 chances to exploit potential sources of chemical energy of the most 

 diverse type. x\dding to this the surprising ubiquity of a great number 

 of germs which apparently are widely transported through the air 

 from a soil teeming with life, it is easily understood that the most 

 divergent industries are liable to microbial invasions which may lead 

 to definitely troublesome effects. 



It is, therefore, not surprising that this continuous struggle of man 

 against microbial life has given rise to industries in which the defence 

 against this menace has become the main purpose. I have already 



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