Influence of pH on the Dissimilation of Glucose by Aerobacter indologenes.

Osburn, Brown and Werkman (1937) observed a critical pH level in the dissimilation of glucose by Clostridium butylicum near 6.3. Above this level butyl alcohol and isopropyl alcohol were not formed. The significance of this critical pH was attributed to the fact that in mixtures of acetic (or butyric) acid and its sodium salt below 6.3 there will be "free" acid, i.e., acid which can be distilled from solution and can be converted into alcohols by C. butylicum. This concept of critical pH is applied to the dissimilation of glucose by Aerobacter indologenes in the present investigation, particularly with reference to the findings of Reynolds and Werkman (1937), that when sufficient acetic acid is present in a glucose dissimilation by A. indologenes, no gaseous hydrogen is evolved and the acetic acid disappearing in the medium is accounted for as 2, 3-butylene glycol + acetylnethylcarbinol. Their conclusions were to the effect that acetic acid occurring in the fermentation was transformed into 2, 3-butylene glycol + acetylmethylcarbinol. The principle of critical pH probably has a general application to cellular metabolism. Although pH 6.3 was found to be the critical level in the case of C. butylicum in converting butyric and acetic acids into corresponding alcohols, it is likely that each organism will show several such levels which will be determined by the dissociation of the substance subject to change. Furthermore, as pointed out by Osburn and Werkman (1937), the change