Biomass Production Potential of a Wastewater Alga Chlorella vulgaris ARC 1 under Elevated Levels of CO2 and Temperature

Abstract

The growth response of Chlorella vulgaris was studied under varying concentrations of carbon dioxide (ranging from 0.036 to 20%) and temperature (30, 40 and 50°C). The highest chlorophyll concentration (11 μg mL–1) and biomass (210 μg mL–1), which were 60 and 20 times more than that of C. vulgaris at ambient CO2 (0.036%), were recorded at 6% CO2 level. At 16% CO2 level, the concentrations of chlorophyll and biomass values were comparable to those at ambient CO2 but further increases in the CO2 level decreased both of them. Results showed that the optimum temperature for biomass production was 30°C under elevated CO2 (6%). Although increases in temperature above 30°C resulted in concomitant decrease in growth response, their adverse effects were significantly subdued at elevated CO2. There were also differential responses of the alga, assessed in terms of NaH14CO3 uptake and carbonic anhydrase activity, to increases in temperature at elevated CO2. The results indicated that Chlorella vulgaris grew better at elevated CO2 level at 30°C, albeit with lesser efficiencies at higher temperatures.

Growth and biochemical composition of Chlorella vulgaris in different growth media

“…Similar to our study, Chinnasamy et al (2009) protein content (dry weight) was obtained. Our results for protein content in Chu and WC media are about twice higher than those reported by Illman et al (2000), who showed 29% (dry weight) protein production by C. vulgaris in Watanabe medium.…”

Influence of culture media and carbon sources on biomass productivityand oil content of the algae Sirogonium sticticum, Temnogyra reflexa,Uronema elongatum, and Chroococcus turgidus

“…Previous studies have demonstrated that the biomass and lipid content in some microalgae were affected by various cultivation conditions such as nitrogen supply and its sources (Li et al, 2008;Arumugam et al, 2013), salt concentration (Takagi et al, 2006), level of CO 2 (Chinnasamy et al, 2009), light intensity, and temperature (Renaud et al, 2002;Khotimchenko and Yakovleva, 2005;Juneja et al, 2013). These observations allowed us to hypothesize that there might be a profound effect of media type and carbon sources on the biomass and oil content of the microalgae S. sticticum, T. reflexa, U. elongatum, and C. turgidus.…”

An Overview of Algae Biofuel Production and Potential Environmental Impact

“…However, at CO 2 concentrations greater than 6%, Chlorella vulgaris demonstrated a decrease in growth rate with decreasing pH levels. 118 The increase in biomass was observed for protein and carbohydrate, whereas the lipid concentration decreased by 5.8%. 118 This benchtop research demonstrates a useful methodology needed to find the optimal algae growing conditions.…”

“…118 The increase in biomass was observed for protein and carbohydrate, whereas the lipid concentration decreased by 5.8%. 118 This benchtop research demonstrates a useful methodology needed to find the optimal algae growing conditions. A benchtop study conducted by Francisco et al 119 tested six strains of microalgae in a PBR employing CO 2 sequestration.…”

“…Sparging concentrated CO 2 emissions (such as those found in flue gas) into the algal culture can increase the dissolved CO 2 concentration above ambient (0.036%) and elicit an increase in algae growth. 118 Temperature also regulates cellular metabolic functions that can increase algae production. The beneficial increase in metabolism caused by increasing temperature is limited to the point when protein synthesis is affected.…”