Growth and biochemical constituents of an indigenous cyanobacterium affected by heavy metal stress

Abstract

A cyanobacterium having high relative abundance in sewage irrigated soil was isolated and identified as Lyngbya contorta. The species was tested for tolerance towards heavy metals, Cu2+, Zn2+, Ni2+and Cd2+ (0.5 to 10 mg/L) in single metal systems under controlled laboratory conditions. Our results show that the studied strain has a distinctive response towards each heavy metal, it was most affected by Ni2+ followed by Cu2+, Zn2+, Cd2+ ions. The studied strain showed better response as indicated by higher concentrations of sugar, proteins and photosynthetic pigments in aqueous Cd2+ solutions as compared to that at control. The incubation of cyanobacterial cells with lower concentrations of heavy metals (Cu2+, Zn2+, Ni2+) enhanced the growth rate, soluble proteins and photosynthetic pigments, while elevated concentrations were observed to be inhibitory. The present study demonstrates the capability of isolated indigenous species to withstand heavy metal stress at low concentrations and can be utilized for bioremediation of contaminated lands.