Studies in the respiratory and carbohydrate metabolism of plant tissues. II. Interrelationship between the rates of production of carbon dioxide, of lactic acid and of alcohol in potato tubers under anaerobic conditions.

Abstract

Data, presented in part I of this communication, for the changes in air and in nitrogen in the rate of CO2production by potato tubers and in the contents of sugar, lactic acid, alcohol and other constituents, are analyzed and discussed. Certain features of the results indicate that in nitrogen a system producing lactic acid may be competing with systems in which either CO2or CO2and alcohol are formed, for a glycolytic intermediate, possibly pyruvic acid. Stoklasa (1904) observed the formation of lactic acid, together with a considerable amount of alcohol, in potatoes during anaerobiosis. In contrast, Kostytschew (1913) found no alcohol in low-sugar potatoes under anaerobic conditions, but a little alcohol in tubers of high sugar content. In our experiments, also with low-sugar potatoes, lactic acid but no alcohol was formed in the first phase of anaerobiosis; subsequently alcohol was produced in addition to lactic acid. Thus the results of previous workers are to a certain extent reconciled by the present study. When account is taken of the formation, under anaerobic conditions, of lactic acid and alcohol, as well as of CO2, a marked Pasteur effect is shown. The doubts expressed by Choudhury (1939) and Boswell & Whiting (1940), based solely on observations of CO2output, as to the existence of a Pasteur effect in potatoes are thus seen to be unjustified.