Tadeusz Skowroński

Cellular mechanisms of Cu-tolerance in the epilithic lichen Lecanora polytropa growing at a copper mine

Cellular responses to copper stress were investigated for the first time in a saxicolous lichen species, Lecanora polytropa (Hoffm.) Rabenh. Bright blue-green apothecia accumulated up to 1·3% Cu on a dry weight basis (205 μ mol Cu g −1 ), c . 50% in an exchangeable form. A bright turquoise-blue layer extended beneath the hymenium into the medulla, above and between a dentate photobiont layer. Oxalic (1·88 μ mol g −1 ), citric (0·83 μ mol g −1 ) and lower concentrations of malic (0·45 μ mol g −1 ) acids were determined by GC/MS analysis. Short-term exposure to high Cu 2+ concentrations (40 and 400 μ mol g −1 ) under non-complexing conditions caused a dose-dependent decrease in chlorophyll a content; chlorophyll b and total carotenoid contents remained constant. The phaeophytinization quotient remained unchanged during Cu 2+ exposure. Analysis of thiol peptides confirmed glutathione was reduced (GSH) in native L. polytropa (0·538 μ mol g −1 ), and phytochelatins (PC 2 and PC 3 ) oxidised. Short-term exposure to 40 μ mol g −1 Cu 2+ oxidised c . 28% of the glutathione pool; oxidised phytochelatin concentrations remained unchanged. This is the first report of phytochelatin production and thiol peptide status in a crustose lichen. These represent two possible detoxification mechanisms in this Cu-tolerant species. Copper complexation by low molecular mass organic acids and non-protein thiols do not entirely account for its tolerance.

Uptake of cadmium ions in white-rot fungus Trametes versicolor: effect of cd (II) ions on the activity of laccase.

The effects of cadmium Cd (II) ions on the physiology and biological activity of Trametes versicolor, a strain belonging to white‐rotting Basidiomycetes, were examined. Cd (II) ions were added to 10‐day‐old cultures grown on a liquid medium, or at the time of inoculation. Our experiments showed that T. versicolor is a good cadmium biosorbent from aqueous solution, this strain removing almost all the Cd (ll) ions over the first 2h of incubation by what appears to be a rapid, energy‐independent surface binding phenomenon, at the rate of ∼2mg Cd per g mycelial dry weight. An additional slower and energy‐dependent transport mechanism was also present, taking in ∼0.3mg Cd (II) perg dry weight. It is also shown that these Cd (II) ions significantly stimulate the activity of extracellular laccase when added to 10‐day‐old cultures.

The influence of pH on cadmium toxicity to the green alga Stichococcus bacillaris and on the cadmium forms present in the culture medium.

Cadmium toxicity to the green alga Stichococcus bacillaris was investigated in media of pH 3-9. A significant decrease of cadmium toxicity occurred in both the acidic and alkaline ranges of pH. In media of pH 3 and 9, cadmium did not affect the dry mass content substantially. Maximum toxicity of cadmium was noticed at pH 6-7. Voltametric investigations showed a significant effect of pH on electrochemically measured cadmium content in the culture media. Hydrolysis of the medium components and formation of cadmium complexes with OH(-) ions caused a considerable decrease in amounts of electrochemically measured cadmium in the alkaline range of pH.

The impact of inorganic tin on the planktonic cyanobacterium Synechocystis aquatilis: the effect of pH and humic acid.

The influence of inorganic tin compounds on the unicellular cyanobacterium Synechocystis aquatilis was studied, and its dependence on changing pH of the surrounding medium and the presence of humic acid. Both Sn(II) and Sn(IV), used as chlorides (at the concentrations 1-10 mg litre(-1)), inhibit the growth and chlorophyll a content of the cyanobacterium cultures, but only under alkaline conditions. Generally, the observed tin toxicity increased with increase of metal concentration, time of exposure and pH value of the medium (in the range 7-9.8). Sn(II) seems to be more toxic than Sn(IV). At the lowest studied metal concentration (1 mg litre(-1)), Sn(II) caused a 36 and 40% decrease in growth and chl a content, respectively, after 96 h exposure at pH 9.8, while Sn(IV) caused even a slight increase of both physiological parameters (hormetic effect). Similar increases in growth and chl a content were also observed at a high Sn (II) and Sn(IV) concentration (10 mg litre(-1)), but only in cultures exposed to metal at pH 7. At high pH (9.8), 10 mg litre(-1) of Sn(II) and Sn(IV) significantly suppressed both the growth of the cyanobacterium (by 54.2 and 26.1%, respectively) and the chl a content in cultures (by 58.2 and 24%, respectively). Humic acid reduced the toxicity of tin towards the cyanobacterium. The observed effects of pH and complexing ligand on the inorganic tin toxicity are discussed in the context of changing, chemical metal speciation and bioavailability.

Adsorption of cadmium on green microalga Stichococcus bacillaris

Time course of cadmium adsorption on the cells of the green microalga Stichococcus bacillaris as well as the influence of temperature, the bivalent ions (Co2+, Mg2+, Mn2+, Zn2+) and pH on it have been investigated. Adsorption isotherms (Langmuir ones) have been determined at different pH values. The maximal amount of cadmium which can be adsorbed on the cells of S. bacillaris is 11.7 × 10−3 g/g dry weight at pH 7, 6.2 × 10−3 g/g dry wt at pH 6 and 1.4 × 10−3 g/g dry wt at pH 4.

Influence of some physico-chemical factors on cadmium uptake by the green alga Stichococcus bacillaris

SummaryIt has been shown that cadmium transport into Stichococcus bacillaris cells depends on temperature and pH and is inhibited by Mn2+ ions.

Energy-dependent transport of cadmium by Stichococcus bacillaris

Abstract The investigations showed that Stichococcus bacillaris took up cadmium by means of adsorption and energy-dependent transport. Cadmium transport into alga cells was inhibited in the dark as well as under the influence of the uncouplers: 2,4-dinitrophenol (DNP), carbonyl cyanide m-chlorophenylhydrazone (CCCP), and ATPase inhibitor - N, N′ - dicyclohexylcarbodiimide (DCCD). It has also been stated that CCCP caused ATP level decrease in cells.

Cation-exchange capacity of algae and cyanobacteria: A parameter of their metal sorption abilities

SummaryThe potential metal sorption abilities of algae and cyanobacteria were estimated as cation-exchange capacities, using a potentiometric titration method. Unicellular cyanobacteriaAnacystis nidulans, Synechocystis aquatilis, and the green microalgaStichococcus bacillaris revealed a higher maximal capacity (205–825 μeq g−1 dry wt) than filamentous macroalgaVaucheria sp. (Xanthophyceae, 41 μeq g−1 dry wt). The cation-exchange capacity decreased when external pH decreased. Different ion-exchange properties of cell surfaces of cyanobacteria and algae were observed.

Uptake of cadmium by Stichococcus bacillaris

Abstract The uptake of cadmium by the green alga Stichococcus bacillaris was studied. It was found that about 80% of the uptake was due to adsorption, and about 20% to energy-dependent transport. Investigations on the relationship between the sorption of cadmium and the equilibrium concentration (Ce) revealed that the alga cells are saturated at Ce20mg Cd/1.

Cadmium removal by green alga Stichococcus bacillaris

Abstract Cadmium removal by S . bacillaris cells was investigated. At constant biomass density 1 g of dry weight/1 - 60 %–80% of cadmium was removed by algae from the solutions containing to 4 mg Cd/1. The extent of cadmium removal was alga suspension density dependent. Quadruple usage of new algae (of density 1 g dry weight/1) in the solutions containing 0.5 and 4.0 mg of Cd/1 caused cadmium removal in 96%.