Browsing by Author "ESPEJO, E"

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    CATABOLISM OF 1,2-DIARYLETHANE LIGNIN MODEL COMPOUNDS BY 2 BROWN-ROT FUNGI
    (1990) ESPEJO, E; AGOSIN, E; VICUNA, R
    The catabolism of dimethoxybenzil, anisoin and hydroanisoin in nitrogen-limited stationary cultures of the brown-rot fungi Wolfiporia cocos and Gloephyllum trabeum was analyzed. These three 1,2-diarylethane lignin model compounds, which differ in the degree of oxidation of the alkylic chain, gave rise to p-anisaldehyde in both cultures, suggesting that cleavage between the two aliphatic carbons had occurred. In turn, both strains reduced dimethoxybenzil and anisoin to hydroanisoin, whereas only Wolfiporia cocos was able to oxidize hydroanisoin to anisoin. On the other hand, chemically derived hydroxyl radical, but not superoxide radical, produced p-anisaldehyde plus other unidentified compounds from anisoin and hydroanisoin. Neither radical modified dimethoxybenzil significantly.
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    PRODUCTION AND DEGRADATION OF OXALIC-ACID BY BROWN ROT FUNGI
    (AMER SOC MICROBIOLOGY, 1991) ESPEJO, E; AGOSIN, E
    Our results show that all of the brown rot fungi tested produce oxalic acid in liquid as well as in semisolid cultures. Gloeophyllum trabeum, which accumulates the lowest amount of oxalic acid during decay of pine holocellulose, showed the highest polysaccharide-depolymerizing activity. Semisolid cultures inoculated with this fungus rapidly converted C-14-labeled oxalic acid to CO2 during cellulose depolymerization. The other brown rot fungi also oxidized C-14-labeled oxalic acid, although less rapidly. In contrast, semisolid cultures inoculated with the white rot fungus Coriolus versicolor did not significantly catabolize the acid and did not depolymerize the holocellulose during decay. Semisolid cultures of G. trabeum amended with desferrioxamine, a specific iron-chelating agent, were unable to lower the degree of polymerization of cellulose or to oxidize C-14-labeled oxalic acid to the extent or at the rate that control cultures did. These results suggest that both iron and oxalic acid are involved in cellulose depolymerization by brown rot fungi.