Simple method for the estimation of 2-keto-3-deoxy aldonic acids formed by fungi

A simplified colorimetric procedure has been developed for 2-keto- 3-deoxy aldonic acids on the base of previously reported methods using periodate oxidation. The periodate oxidation product is coupled with thiobarbituric acid to form a chromogen whose absorption maximum is at 545 to 550 nm. Cell-free extracts of six Penicillia were analyzed for their ability to degrade D-gluconate and L-arabonate. The formed 2-keto-3-deoxy-D-gluconate [KDG] and 2-keto-3-deoxy-L-arabonate [KDA] were estimated by this method. High yield of KDG was observed in case of Penicillium citrinum, P. Funiculosum and P. Chrysogenum, but a considerable amount of KDA was detected. KDG and KDA were also estimated as a product of C3 + C3 and C3 + C2 reverse reactions of aldolases, respectively. This method is unique in that it can be applied to a large number of microorganisms as a metabolic marker for taxonomic purposes