Bioremoval of humic acid from water by white rot fungi: exploring the removal mechanisms

M. Zahmatkesh, H. Spanjers, M. J. Toran, P. Blánquez, J. B. van Lier

Research output: Contribution to journalArticleResearchpeer-review

16 Citations (Scopus)

Abstract

© 2016, The Author(s). Twelve white rot fungi (WRF) strains were screened on agar plates for their ability to bleach humic acid (HA). Four fungal strains were selected and tested in liquid media for removal of HA. Bioremediation was investigated by HA color removal and changes in the concentration and molecular size distribution of HA by size exclusion chromatography. Trametes versicolor and Phanerochaete chrysosporium showed the highest HA removal efficiency, reaching about 80%. Laccase and manganese peroxidase were measured as extracellular enzymes and their relation to the HA removal by WRF was investigated. Results indicated that nitrogen limitation could enhance the WRF extracellular enzyme activity, but did not necessarily increase the HA removal by WRF. The mechanism of bioremediation by WRF was shown to involve biosorption of HA by fungal biomass and degradation of HA to smaller molecules. Also, contradicting previous reports, it was shown that the decolorization of HA by WRF could not necessarily be interpreted as degradation of HA. Biosorption experiments revealed that HA removal by fungal biomass is dependent not only on the amount of biomass as the sorbent, but also on the fungal species. The involvement of cytochrome P450 (CYP) enzymes was confirmed by comparing the HA removal capability of fungi with and without the presence of a CYP inhibitor. The ability of purified laccase from WRF to solely degrade HA was proven and the importance of mediators was also demonstrated.
Original languageEnglish
Article number118
JournalAMB Express
Volume6
Issue number1
DOIs
Publication statusPublished - 1 Dec 2016

Keywords

  • Biodegradation
  • Biosorption
  • Cytochrome P450
  • Humic acid
  • Laccase
  • Manganese peroxidase
  • White rot fungi

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