Studies on the effect of elevated levels of CO2 on the growth and metabolites of indigenous microalgal isolates.

Namratha, S. Hegde (2013) Studies on the effect of elevated levels of CO2 on the growth and metabolites of indigenous microalgal isolates. [Student Project Report] (Submitted)

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Abstract

The present study is focused on the utilization of indigenous microalgae for CO2 sequestration. Five microalgae of genus Oocystis sp. (KA 7 1), Scenedesmus sp. (KA 7 2 and KA 7 RC), Kirchneriella sp. (HT BG 11) and Pyramimonas sp. (KA 5 SC) were screened for their tolerance to CO2 levels (5, 10, 20 and 30%) and effect of CO2 concentration on the cellular metabolites was studied. It was observed that Scenedesmus sp. (KA 7 RC) and Pyramimonas sp. (KA 5 SC) showed high specific growth rate of 0.162 g/l/d and 0.155 g/l/d with biomass yield of 0.81g/l and 0.78g/l respectively under 30% of CO2. The chlorophyll pigment increased from 31.05 to 37.72μgm/ml for KA 7 RC and from 3.76 to 13.27μgm/ml for KA 5 SC. There was also increase in carotenoid content. Total lipid content of the microalgae was also estimated as a function CO2. Lipid content of high CO2 tolerant isolates, KA 7 RC and KA 5 SC, was around 21.2% and 18% respectively at 20% of CO2. Fatty acid profile of the cultures indicated that increase in the CO2 concentration was favourable for accumulation of unsaturated fatty acids. The present results suggest that the indigenous microalgae have potential for CO2 fixation and production of value added products. The enzyme Carbonic Anhydrase (CA) is an important component of Carbon Concentrating Mechanism. Its activity was measured in cultures supplied with different levels of CO2. Supply of CO2 led to decrease in culture pH, availability of free CO2 and increased levels of bicarbonate in culture medium. It was observed that, CA activity remains low in presence of free CO2 and increases with the depletion of free CO2 from the medium. Increased enzyme activity corresponds with the decrease in bicarbonate levels suggesting the utilisation of bicarbonate by microalgae through the activity of CA enzyme.

Item Type:	Student Project Report
Uncontrolled Keywords:	indigenous microalgae, Carbon dioxide concentration, value added products
Subjects:	500 Natural Sciences and Mathematics > 08 Botanical sciences > 01 Botany > 01 Algae
Divisions:	Plant Cell Biotechnology
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	04 Apr 2014 05:08
Last Modified:	04 Apr 2014 05:08
URI:	http://ir.cftri.res.in/id/eprint/11444

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