title: Modification of humic acids by the compost-dwelling deuteromycete Paecilomyces inflatus.
abstract: The soil mold Paecilomyces inflatus is capable of modifying and partially mineralizing synthetic and natural humic acids (HAs) in compost environments. HA degradation studies using a synthetic HA (14C-HA) in autoclaved compost microcosms showed that, after 12 weeks of cultivation, P. inflatus mineralized approximately 5% of the 14C-labeled HA to 14CO2, while 6% of the 14C-HA was converted into 14C-labeled water-soluble fragments (fulvic-acid-like fraction). About 40% was still present as NaOH-soluble HA representing unmodified or only slightly modified humic material (compared with 60% in the controls). Modification of natural HAs extracted from compost was followed by their partial decolorization (30%) in liquid cultures of P. inflatus. Bleaching of the medium was accompanied by moderate changes in the molecular mass distribution of both the HA and fulvic-acid fractions, which were analyzed with high-performance size exclusion chromatography. HA modification was most pronounced during the primary growth phase of the fungus and was associated with increased laccase activity.
authors.affiliation: Department of Applied Chemistry and Microbiology, Viikki Biocenter 1, University of Helsinki, Viikinkaari 9, P.O. Box 56, 00014, Helsinki, Finland.
authors.forename: Beata
authors.initials: B
authors.lastname: Kluczek-Turpeinen
authors.forename: Kari T
authors.initials: KT
authors.lastname: Steffen
authors.forename: Marja
authors.initials: M
authors.lastname: Tuomela
authors.forename: Annele
authors.initials: A
authors.lastname: Hatakka
authors.forename: Martin
authors.initials: M
authors.lastname: Hofrichter
mesh_terms: D002250:Carbon Radioisotopes; D003116:Color; D006812:Humic Substances / Q000032:analysis*; D008970:Molecular Weight; D010143:Paecilomyces / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D012988:Soil Microbiology
chemical_list: D002250:Carbon Radioisotopes; D006812:Humic Substances