1Department of Microbiology, Maharshi Dayanand Saraswati University, Ajmer, Rajasthan 305 009
2National Centre for Conservation and Utilisation of Blue Green Algae, Indian Agricultural Research Institute, New Delhi, 110 012
*Corresponding author; E-mail: aridgabga@hotmail.com Tel: 91(145)2644133
Seven cyanobacteria and five green algae were exposed to varied concentrations of fluoride for a period of 15 d. LC50 for these forms varied from 53 to 375 mg F mL−1 suggesting that ambient fluoride concentrations in nature are non toxic to the native microalgae. At higher concentrations cyanobacteria were comparatively more sensitive than green algae. Fluoride toxicity in Anabaena khannae was found to increase at low pH. Chlorococcum humicola appeared to evade the toxic effect probably due to its thick cellulosic cell wall compared to the more primitive murein wall of Anabaena as well as due to internal compartmentalisation by unit membranes.
Algae, cyanobacteria, fluoride, pH
