Effect of elevated level of CO2 on Kirchneriella sp., a microalga, under salinity and nitrogen stress.

Kamala, Shiny. S (2013) Effect of elevated level of CO2 on Kirchneriella sp., a microalga, under salinity and nitrogen stress. [Student Project Report] (Submitted)

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Abstract

The present study is focused on the effect of stress conditions in microalga Kirchneriella sp which was grown under ambient (0.03%) and elevated level of CO2 (20%) . The stress condition selected was nitrogen at 0.008 M, 0.004 M and 0.0017M of NaNO3 and salinity at 0.04M, 0.085M, 0.127M and 0.17M NaCl. The cellular metabolites were studied in the culture under these conditions. Biomass yield clearly indicate the growth promoting and salinity stress alleviating effect of 20% CO2 up to 0.13M level of NaCl in medium. The cultures under all the tested levels of nitrogen stress showed no significant increase in the biomass yields with ambient level of CO2. The total chlorophyll content under salinity stress shows that under ambient level control culture and cultures under 0.04 M and 0.13 M NaCl was in the range of 22-30 μgm/ml and under elevated level the cultures under 0.08 M and 0.13 M NaCl show comparatively lower chlorophyll content. The total chlorophyll content in nitrogen stress under supplementation with 20% CO2 was about 22-24 μgm/ml which is almost two fold increase than the chlorophyll content achieved under ambient level of CO2. There was also increase in carotenoid content. Total lipid content of the microalga was also estimated as a function CO2 . Under elevated levels of CO2, the lipid content of all the cultures at all the tested levels of NaCl showed an enhancement of lipid content. Total lipid content with nitrogen stress suggested that reduced nitrogen level lead to an increase of lipid content by about 12% over control cultures under ambient level of CO2 and on supplementation with elevated levels of CO2, there was a 34% increase in lipid content in control culture. Fatty acid profile of the cultures indicated that ambient level was favourable for accumulation of unsaturated fatty acids. The enzyme Carbonic anhydrase (CA) is an important component of carbon concentrating mechanism. Its activity was measured in cultures under nitrogen stress (supplied with nitrogen at 0.004M NaNO3) under ambient and elevated levels of CO2. Supply of CO2 led to decrease in culture pH, availability of free CO2 and decreased levels of bicarbonate in culture medium. The activity of carbonic anhydrase in elevated CO2 supplied cultures is higher than the cultures supplied with ambient level of CO2.

Item Type:	Student Project Report
Uncontrolled Keywords:	Kirchneriella sp, salinity stress, nitrogen stress, biomass yield, lipid, carotenoid
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:	12 May 2014 05:17
Last Modified:	12 May 2014 05:17
URI:	http://ir.cftri.res.in/id/eprint/11566

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