Organic Acid Production by Basidiomycetes

TAKAO, SHOICHI (Hokkaido University, Sapporo, Japan). Organic acid production by Basidiomycetes. I. Screening of acid-producing strains. Appl. Microbiol. 13:732737. 1965.-Sixty-seven strains belonging to 47 species of Basidiomycetes were examined for their acid-producing abilities in glucose media, in both the presence and absence of CaCO3, in stationary and shake cultures. Some strains were found to produce large quantities of oxalic acid. The oxalic acid-producing strains could be 8eparated into two groups. Strains of one group (mostly brown-rot fungi) were able to produce oxalic acid, regardless of whether CaCO3 was present in the medium. Strains of the other group (mostly white-rot fungi) were characterized by their ability to produce oxalic acid only when CaCO, was added to the medium. With the latter group, shake-culturing was generally more effective than stationary culturing in respect to acid production. In the CaCO3-containing media, Schizophyltum commune, Merulius tremellosus, and Porodisculus pendulus were found to produce substantial amounts of L-malic acid as a main metabolic product, along with small quantities of oxalic and other acids in shake cultures. Especially, S. commune and M. tremellosus may be employed as malic acid-producing species. Basidiomycetes comprise a very large number of species within the Eumycetes. Extensive studies concerning the metabolic products of fungi and yeasts have been undertaken. On the other hand, many of the biochemical investigations of Basidiomycetes have been carried out with emphasis on the nutritional, medicinal, or toxic effects of materials present in their fruiting bodies. Moreover, there are relatively few reports on their metabolic products, with the exception of oxalic acid, antibiotics, and certain other compounds. Based on these facts, many kinds of Basidiomycetes were cultured to compare their metabolic features, especially acid-producing abilities, and to detect valuable end products. As a result, it was found that some strains produced large amounts of oxalic acid, and some others had the capacity to produce substantial amounts of L-malic acid as a main product from glucose. De Bary (1886) first found potassium oxalate deposited in Peziza sclerotinia, and later calcium oxalate, or free oxalic acid, was observed in several kinds of Basidiomycetes (Zellner, 1907). On the other hand, after Sakaguchi and Nakao (1931) obtained oxalate in the culture solution of Cortinellus shiitake (present name, Cortinellus edodes), many species of Basidiomycetes were studied for oxalic acid production, including Armillaria mellea (Hamada, 1940), Coniophora cerebella (Birkinshaw, Findlay, and Webb, 1940), Merulius niveus, M. tremellosus, M. confluens, Fomes annosus (Nord and Vitucci, 1947), Poria vaporaria (Fukinbara, 1948; Shimazono, 1951; Kamibayashi and Nakatai, 1960), Merulius lacrymans, Marasmius chordalis (Smith, 1949), Polyporus anceps (Perlman, 1949), Fomitopsis pinicola, Piptoporus betulinus (Shimazono, 1951; Kamibayashi and Nakatai, 1960), Fomitopsis sp., Phaeolus schweinitzii, Stereum frustolosum, Trametes albida, T. dickinsii, Tyromyces sambuceus (Shimazono, 1951), Trametes cinnabarina (De Stevens, De Baun, and Nord, 1951), Corticium centrifugum (Nagata and Hayashi, 1956; Kamibayashi and Nakatai, 1960), Coniophora puteana, Daedalea quercina, Fomitopsis officinalis, Laetiporus sulphureus, Polyporus palustris (Kamibayashi and Nakatai, 1960), Pleurotus ostreatus (Tsao, 1963a), and Agaricus campestris (Tsao,