Keratinolytic and Non-Keratinolytic Fungi in Sewage Sludge
Krzysztof Ulfig1, Grażyna Płaza2, Agata Markowska-Szczupak3, Katarzyna Janda4, Sylwia Kirkowska1
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1Division of Biomaterials and Microbiological Technologies, Polymer Institute,
West Pomeranian University of Technology, Pułaskiego 10, 71-322 Szczecin, Poland
2Institute for Ecology of Industrial Areas, Kossutha 6, 40-844 Katowice, Poland
3Institute of Chemical and Environment Engineering,
West Pomeranian University of Technology, Pułaskiego 10, 71-322 Szczecin, Poland
4Department of Processing and Storage of Plant Raw Material,
West Pomeranian University of Technology, Słowackiego 17, 71-434 Szczecin, Poland
Pol. J. Environ. Stud. 2010;19(3):635–642
Sewage sludge is being used for reclamation of devastated areas and for fertilization of arable soils. However, sludges contain many harmful components, including pathogenic organisms. Many keratinolytic and associated non-keratinolytic fungi are opportunistic pathogens. Our knowledge on fungal occurrence in sludges and sludge-amended soils and on the health risk posed by the fungi is still not sufficient. The present work was part of extensive studies on actidione-resistant fungal pathogens in sludges and sludge-amended soils. Sludges from the Siemianowice-Centrum wastewater treatment plant, Upper Silesia, Poland were examined. Results obtained by means of three methods, i.e. the dilution pour plating method, hair baiting method and most probable number method were compared. The MPN method combines the dilution and hair baiting methods. The dilution pour plating method was found not to be highly informative as to the occurrence of keratinolytic fungi in sludges, while using the method more information was obtained on non-keratinolytic fungi in the sludge environment. Subsequently, the hair baiting method provided the data on fungal growth in the hair spread over the sludge blanket. This qualitative method has often been used for semiquantitative purposes but does not allow for determining fungal quantities. Such quantities were obtained using the MPN method. The method complemented the results obtained using two other methods. The hair baiting and MPN methods use hair and natural media (sterile sludge, sand, and clay) for examination of sludge fungi. The selectiveness of the MPN method was even higher than that of the hair baiting method. Ecological and epidemiological significance of the MPN results was discussed.