STUDIES ON THE MICROORGANISM PRODUCING ISOPROPANOL FROM ACETONE

PART 2. ENZYME INVESTIGATION ON THE OXIDATION-REDUCTION OF LACTOBACILLUS BREVIS VAR. HOFUENSIS

Abstract

(1) The composition of medium for the enzymatical experiments of Lactobacillus brevis var. hofuensis was investigated and two media were determined as inoculum and accumulation media.
(2) Acetone was reduced by intact cell, cell-free extract and residue of extract and it was found that glucose played a role for the reduction of acetone by these preparations.
(3) Oxidation-reduction potentials of the dehydrogenation systems by alcohols and polyols were measured and the potential of isopropanol dehydrogenation was proved at -0.3 volt.
(4) Oxygen-uptake by isopropanol and ethanol was examined under various conditions and it was demonstrated than isopropanol exceeded ethanol.
(5) Cofactors about dehydrogenation of isopropanol and ethanol are DPN and TPN. DPN-specificity is less than 1/10 of TPN.
(6) The incorporation between glycolysis and reduction of substrate was elucidated. Oxidation of glucose-6-phosphate or 6-phosphogluconate and reduction of acetone, acetaldehyde or other substances were coupled by way of oxidation-reduction of TPN.
(7) Inhibitors experiments clarified the reductions of acetone and acetaldehyde as the different reactions.
(8) Comparing the oxidation-reduction of isopropanol/acetone with ethanol /acetaldehyde it was suggested that the former reaction is oxidative.
(9) This microorganism has the flavoprotein analogous to cytochrome c reductase and the specific terminal oxidase.
(10) The flavoprotein exhibits the peaks of different spectrum at 380 mμ and 445mμ and links to the dehydrogenase of isopropanol and results in its oxidative activity.
(11) The name of isopropanol dehydrogenase was designated to the enzyme concerning oxidation-reduction between isopropanol and acetone.
(12) This enzyme relates to the dehydrogenation of secondary butanol and 1.2 propylene glycol.