Metal–salt co-tolerance and metal removal by indigenous cyanobacterial strains

Abstract

Chromium and salt tolerance in five indigenous cyanobacterial strains isolated from contaminated sites was investigated along with their metal bioaccumulative potential. All the five species showed significantly better growth when the medium was spiked with salt or chromium. As compared to single metal or salt treatment, the binary metal–salt (MS) treatments had more favorable effect on cyanobacterial growth as indicated by significantly higher concentration of the primary photosynthetic pigment chlorophyll at M 20S 2000 (9.9–25.3 μg/mL) as compared to that at M 0S 0 (4.0–12.3 μg/mL). Similarly biomass was much higher at M 20S 1000 and M 20S 2000 (41.8–86.2 mg/10 mL) as compared to that at control, M 0S 0 (21.5–36.3 mg/10 mL). Accessory pigments like carotenoids and phycobilinproteins too tended to increase significantly in response to both metal and salts in the two species of Lyngbya ( L. putealis and L. ceylanica var. constricta) and Gloeocapsa. These species also showed greater potential of chromium bioaccumulation, which increased further as both salt and metal concentration increased. In the two species of Nostoc however, bioaccumulative potential improve at higher metal concentration, but not affected significantly by salt concentration.