Responses of the phosphatase activity of the lichen Cladina rangiferina to various environmental factors including metals

Abstract

The characteristics of phosphatase activity of Cladina rangiferina (L.) Harm, have been studied. Calculations of enzyme activities were based on the liberation of p-nitrophenol from p-nitrophenyl phosphate. The phosphatase activity was found to be linear both with increasing sample size (enzyme concentration) and increasing time, showed highest activity at acidic pH, and had a Michaelis–Menten constant of 8.9 × 10−3 M. The enzyme activity was maximal in the range 61 ± 10 °C, was independent of light, and was completely eliminated by boiling the thalli. Various cations and anions were tested for their effect; uranyl and vanadyl ions inhibited activity by 60% whereas copper, nickel, and silver enhanced activity by 10%. The anions biselenite, cyanide, fluoride, molybdate, phosphate, and vanadate all greatly reduced activity (≥ 50%). Phosphatase activity was demonstrated in other lichen species.