Isolation of native flue gas tolerant microalga from a mixed culture grown under stress condition

Microalgae have enormous application in the field of pollution reduction, carbon sequestration, biofuel etc. Tropical countries have rich diversity of microalgae which are not yet studied for its potential in different applications. In this regard, the present work aims to isolate and culture native flue gas tolerant microalgal species from mixed culture by growing them in photobioreactor under experimental stress condition. The flue gas produced from a two stroke gasoline burning engine and a diesel engine which was directly supplied to the mixed microalgae culture and its growth was compared with microalgae growing under pure carbon dioxide supplied from cylinder, air from aerator and normal air diffusion. The microalgal culture medium was subjected to the above conditions for 4hr/day, until most of the species in the mixed culture perish. The medium was analyzed for pH, optical density (OD), dissolved carbon dioxide, nitrate, phosphate and selected heavy metals. Results showed that the pH and biomass values were decreased from 7.99 to 6.82 and 0.025mg/l to 0.006mg/L cells respectively for petrol engine exhaust gas fed photobioreactors. The biomass has shown decline in diesel engine exhaust gas fed photobioreactors from 0.096mg/L to 0.06mg/L after 120hrs. Most of the species present in the initial culture was present in the medium after the experiment, but with reduced size and biomass. The tolerant species that could be fruitfully isolated and cultured under normal condition was Chlorella sp.