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A primary alcohol dehydrogenase has been purified from Methylococcus capsulatus (Texas strain). The purified enzyme catalyzes the oxidation of methanol and formaldehyde to formate; other primary alcohols are oxidized to their corresponding aldehydes. Ammonium ions are required for enzyme activity. The enzyme has a molecular weight of 120,000 daltons and consists of two 62,000 molecular-weight subunits which dissociate at acidic p H. The enzyme is similar to an alcohol dehydrogenase enzyme isolated from Pseudomonas sp. M27.

Conventional serodiagnosis of Pythium insidiosum infections involves the use of the immunodiffusion (ID) test. This test specifically diagnoses human and animal pythiosis. The test, however, has limited sensitivity and does not detect some culturally proven cases of the disease. Because of the increased recognition of pythiosis among humans and animals, we developed and evaluated an enzyme-linked immunosorbent assay (ELISA) using a soluble antigen from broken hyphae of P. insidiosum. Studies were carried out with sera from five humans and eight animals with culturally and/or histologically proven pythiosis. Some of these sera were negative in the ID test for pythiosis. Heterologous case sera from thirteen humans and two horses, plus 5 sera from healthy humans and 17 from healthy animals, were tested. Of the pythiosis case sera tested, the ID test detected only 8 of 13 (61.5%), whereas the ELISA detected all of them (100%). The ID and ELISA tests were entirely specific and gave negative results or low titers respectively, with sera from humans and animals with heterologous fungal infections or with no apparent illness. No correlation was found between the height of the ELISA titers and negative or positive sera in the ID test. Our results indicate that the ELISA is a reliable serodiagnostic test for pythiosis. It is as specific as the ID test but more sensitive.

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A primary alcohol dehydrogenase was purified from cell extracts of two apparently unrelated microorganisms, namely, Pseudomonas sp. M27 and Methylococcus capsulatus. Rabbit antiserum prepared against the purified enzyme from M. capsulatus revealed distinctive antigenic determinants by quantitative and gel precipitin reactions. Rabbit antiserum to M27 enzyme detected both distinctive and shared antigenic determinants. Certain methaneand methanol-oxidizing bacteria were grouped on the basis of serological cross-reacting enzyme specificities. Pseudomonas sp. M27 and Methylococcus capsulatus are representative of two apparently unrelated groups of microorganisms (1, 18). Nevertheless, the two organisms are similar in certain physiological properties, particularly with reference to the oxidation of C-1 compounds. For example, cell suspensions of both organisms oxidize methane, methanol, formaldehyde, and formate to carbon dioxide (18). Recently, a nonspecific primary alcohol dehydrogenase (PAD) was purified from cell extracts of methanol-grown M. capsulatus and Pseudomonas M27 (2, 17). A comparison of the biochemical and physical properties of the PAD from the two organisms showed similarities in substrate specificity, requirement for ammonium ions, molecular weight, and subunit composition. Also, the purified enzymes had identical absorption properties, with optima occurring at 260 and 350 nm. It was suggested, therefore, that the enzymes operate by identical oxidative mechanisms, perhaps involving a heretofore unknown pteridine derivative (17). The purified enzymes, however, differ in their electrophoretic mobilities (17). Disc gel