Interactions between a soil fungus, Trichoderma harzianum, and IIb metals—adsorption to mycelium and production of complexing metabolites

• Fungi are capable of accumulating metals and, in soil, such accumulation may influence metal speciation and transport. The interactions between a common soil fungus, Trichoderma harzianum, and IIb elements were studied in the present investigation. The accumulation of the metals zinc, cadmium and mercury by starved and non-starved mycelium at different pH was determined by a batch technique using radioactive tracers; uptake of the metals was found to be large, with respective distribution coefficients of about 10(3.5), 10(2.5) and 10(4.0) for zinc, cadmium and mercury, respectively. Metal accumulation by a starved system was largely independent of pH in the range 3-9, where in a non-starved system an increased accumulation of zinc (at 10(-8) m) was observed at low pH (3-5). Potentiometric titrations performed on the two systems revealed significant differences in acid capacities, i.e. values close to zero for the starved system and 500-800 meq kg-1 for the non-starved system. The maximum metal uptake was at least 50 mmol kg-1 at pH 6.5 (calculated from adsorption isotherms). The present findings suggests that in the non-starved system a metabolite is produced and then released when the pH is within a certain range.

Subject headings

NATURVETENSKAP  -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)

Keyword

adsorption; complexes; IIb metals; Trichoderma harzianum

Publication and Content Type

ref (subject category)

art (subject category)