Yukio Imada

Microbial production of cis, cis-muconic acid from benzoic acid

SummaryThe authors isolated numerous microorganisms with the capacity to assimilate large amounts of benzoate from many soil samples. Several of them were selected and subjected to mutation mainly by ultraviolet irradiation. One mutant lacking active muconate-lactonizing enzyme, the parent strain of which was identified as belonging to the genus Arthrobacter, was isolated and found to be capable of producing cis, cis-muconic acid with a quantitative yield of 44.1 g/l over 48 h in a 30 1 jar fermentor by successive feeding of small amounts of benzoate. This mutant, however, was more sensitive to high concentrations of the substrate than the parent strain. As few intermediates and isomers other than cis, cis-muconic acid were accumulated in the large fermentor, a large amount of pure cis, cis-muconic acid was easily obtained from the broth by salting out and recrystallization at a high recovery rate.

Conversion of methanol to formic acid through the coupling of the enzyme reactions of alcohol oxidase, catalase and formaldehyde dismutase

SummaryA novel process for the production of formic acid from methanol has been developed that involves the coupled reactions of the three enzymes, alcohol oxidase, catalase and formaldehyde dismutase. In this process, methanol is oxidized to formaldehyde by alcohol oxidase and catalase, followed by the formaldehyde dismutase reaction that leads to the formation of methanol and formic acid. Ultimately, the substrate methanol (100 to 200 mM) is completely converted to formic acid, by the recycling of the consecutive enzyme reactions.

Formate production from methanol by formaldehyde dismutase coupled with a methanol oxidation system

SummaryFormaldehyde dismutase was greatly stabilized by immobilization in a urethane prepolymer (PU-6). The immobilized enzyme exhibited stochiometrical dismutation of formaldehyde to methanol and formate in several repeated reactions. Conversion of methanol to formate occurred in a reaction with an immobilized enzyme system consisting of alcohol oxidase, catalase and formaldehyde dismutase, and with an intact cell-mixture of Hansenula polymorpha and Pseudomonas putida. Furthermore, the stability of the cell-mixture during repeated reactions was greatly improved by the immobilization, the 600 mM methanol added periodically being converted to formate in a 75% yield in 12 h. The immobilized cellsystem was also effective for the conversion of several aliphatic alcohols, C1 to C4, to the corresponding acids.