Formation and action of lignin-modifying enzymes in cultures of Phlebia radiata supplemented with veratric acid
- Univ. of Helsinki (Finland)
- Univ. of Maria Curie-Sklodowska, Lublin (Poland)
Transformation of veratric (3,4-dimethoxybenzoic) acid by the white rot fungus Phlebia radiata was studied to elucidate the role of ligninolytic, reductive, and demeth(ox)ylating enzymes. Under both air and a 100% O{sub 2} atmosphere, with nitrogen limitation and glucose as a carbon source, reducing activity resulted in the accumulation of veratryl alcohol in the medium. When the fungus was cultivated under air, veratric acid caused a rapid increase in laccase (benzenediol:oxygen oxidoreductase; EC 1.10.3.2) production, which indicated that veratic acid was first demethylated, thus providing phenolic compounds for laccase. After a rapid decline in laccase activity, elevated lignin peroxidase (ligninase) activity and manganese-dependent peroxidase production were detected simultaneously with extracellular release of methanol. This indicated apparent demethoxylation. When the fungus was cultivated under a continuous 100% O{sub 2} flow and in the presence of veratric acid, laccase production was markedly repressed, whereas production of lignin peroxidase and degradation of veratryl compounds were clearly enhanced. In all cultures, the increases in lignin peroxidase titers were directly related to veratryl alcohol accumulation. Evolution of {sup 14}CO{sub 2} from 3-O{sup 14}CH{sub 3}-and 4-O{sup 14}CH{sub 3}-labeled veratric acids showed that the position of the methoxyl substituent in the aromatic ring only slightly affected demeth(ox)ylation activity. In both cases, more than 60% of the total {sup 14}C was converted to {sup 14}CO{sub 2} under air in 4 weeks, and oxygen flux increased the degradation rate of the {sup 14}C-labeled veratric acids just as it did with unlabeled cultures.
- OSTI ID:
- 6143172
- Journal Information:
- Applied and Environmental Microbiology; (USA), Vol. 56:9; ISSN 0099-2240
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
FUNGI
ENZYME ACTIVITY
LIGNIN
BIODEGRADATION
OXIDOREDUCTASES
BIOCHEMICAL REACTION KINETICS
CARBON 14 COMPOUNDS
TRACER TECHNIQUES
CARBOHYDRATES
CHEMICAL REACTIONS
DECOMPOSITION
ENZYMES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
ORGANIC COMPOUNDS
PLANTS
POLYSACCHARIDES
REACTION KINETICS
SACCHARIDES
550201* - Biochemistry- Tracer Techniques