Pigment system of cyanobacteria in the presence of heavy metals

Abstract

In the conditions of a model laboratory experiment the influence of silver, cadmium, lead, copper salts and different lead salts (an acetate and nitrate) on pigment system of filamentous cyanobacteria was studied. It was revealed that silver ions have the maximum toxic effect (cyanobacteria development was observed at a concentration of 0.002 mg/l), and lead ions have the least toxic effect (cyanobacteria development was observed at concentrations of 0.002 - 20 mg/l). It was noted that the studied heavy metals in low concentrations (0.002-0.02 mg/l) stimulate the formation of chlorophyll a up to 216%, carotenoids up to 133% and phycobilin pigments up to 50 times. It was found that lead acetate has a stimulating effect on the synthesis of photosynthetic pigments. The content of chlorophyll a grew by 30.6%, carotenoids by 24.0% at one Maximum Permissible Concentration (MPC). Lead nitrate had the expressed inhibiting effect on synthesis of photosynthetic pigments. Depression of concentration of chlorophyll a and carotenoids by 38.8% and 79.4% respectively was observed already at one maximum allowable concentration. The stimulating effect of lead acetate is noted on synthesis of phycocyanin (by 94.0%) and allophycocyanin (by 120.0%) in concentration up to 5 times of the MPC; the stimulating effect of lead nitrate was observed on synthesis of phycocyanin (by 64.7%) in concentration up to 5 times of the MPC and on synthesis of allophycocyanin (up to 140.0%) and on phycoerythrin (up to 228.0%) at concentration up to 10 times of the MPC. Comparison of influence of various lead salts on filamentous cyanobacteria revealed a more expressed inhibiting effect of the nitrate form of lead in comparison with acetate.