Effects of fungi on the distribution of metals in soil systems
1993 (English)Doctoral thesis, comprehensive summary (Other academic)
Fungal biomass has previously been shown to be an effective adsorbent for recovery of metals from heavily polluted wastes and waters. Most studies of metal accumulation properties by fungi have therefore been performed at high metal concentrations and using preconditioned fungal biomass. Since fungi constitute, the 'largest group of microbial organisms in soil, on a weight basis, and, as indicated possess a high metal-accumulating capacity, they should indeed be considered to be important metal adsorbents. The aim of the present study was to improve the understanding of the impact of fungi on the mobility of trace metals in natural soil systems. Experimental work was therefore conducted under chemical and biological conditions relevant in uncontaminated soils.
Three different soil fungi (Mortierella isabellina, Penicillium spinulosum and Trichoderma harzianum) were selected. They all showed a considerable ability to accumulate IIb metals (Zn, Cd and Hg). The accumulation by starved mycelia had a limited pH dependence at low metal concentrations, while non-starved mycelia showed an increased accumulation at low pH. This increase appeared to be related to a production of hydrophilic organic compounds. The high ability to accumulate metals at low pH can be explained by the existence of metal-specific sites in the fungal cell walls.
Calculations of the hypothetical distribution of a divalent cationic element in a model soil system indicated the potential importance of fungal metal accumulation in soils. Due to the specific accumulation of metals by the fungi at low pH the fraction associated to the fungal biomass could be considerable and in some cases predominant. A multi compartment system was constructed to corroborate these calculations. This design wasfound to be of great value for simultaneous de terminations of metal partitioning between different soil constituents present in relevant proportions. The results from this system closly resembled the hypothetical calculations.
The accumulation of metals by fungi leading to higher metal concentrations in association with the fungal biomass had an impact on the degradability of the mycelia. A considerable inhibition of this degradation was observed under certain conditions.
The general conclusion of this thesis is that fungi constitute an important soil component for the partitioning of trace metals between stationary and mobile forms. In particular, acidification of soils must be considered in perspective of the qualitative features of the accumulation processes.
Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 1993. , 56 p.
Linköping Studies in Arts and Science, ISSN 0282-9800 ; 96
Metaller, förorenande ämnen, Markföroreningar
Social Sciences Interdisciplinary
IdentifiersURN: urn:nbn:se:liu:diva-35082Local ID: 24819ISBN: 91-7871-164-9OAI: oai:DiVA.org:liu-35082DiVA: diva2:255930
1993-10-29, Sal Elysion, Hus-T, Universitetsområdet Valla, Linköping, 10:10 (Swedish)
Papers, included in the Ph.D. thesis, are not registered and included in the posts from 1999 and backwards.2009-10-102009-10-102012-09-04Bibliographically approved