Groundwater is the major source of drinking water in
most part of the world. However due to the human
activities this water is highly contaminated with
different kinds of pollutant. For example livestock
farming and application of fertiliser increase the amount of nitrate concentration to a level that is
harmful to living organisms. Since cyanobacteria
require nitrogen for metabolism, the removal of nitrate
by these organisms is usually very effective. Three
different cyanobacterial species were used for the
removal of nitrate from groundwater by Hu et al.
(2000). All the species effectively removed nitrate but
Synechococcus sp. strain PCC7942 showed the highest
removal compared to strain PCC6803 and Synechocystis
minima CCAP148014.