ZINC TOLERANCE IN PHORMIDIUM-UNCINATUM

Growth response of Phormidium uncinatum, a filamentous cyanobacterium without heterocysts, in the presence of graded concentrations of zinc was studied in pure culture. Growth at higher zinc concentrations was lower than the control. Tolerance to zinc (50 ppm) was induced in this strain by gradually transferring it to higher concentrations of Zn. T he Zn-tolerant strain in turn developed tolerance to other heavy metal s, eg. Cd, Pb, along with resistance to infection by LPP-1 cyanophage, as distinct from the normal Zn sensitive strain.