Effect of combined nitrogen sources on heterotrophic growth of a blue-green alga Westiellopsis prolifica.

The autotrophic and photoheterotrophic growth of light pre-treated and dark pre-treated strains of Westiellopsis prolifica was decreased in the presence of NH4+, NO3-- and urea in the culture medium. On dark incubation, after pre-treatment with light as well as in the dark, the alga showed better growth response to all the combined nitrogen sources. However, only the light pre-treated strain of the organism utilized the exogenous nitrogen sources appreciably for its dark heterotrophic growth.