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Table 3 C. vulgaris culturing characteristics when grown under various inorganic carbon regimes

From: Optimized inorganic carbon regime for enhanced growth and lipid accumulation in Chlorella vulgaris

Treatment Cell concentration (×107 cells mL−1) Specific growth rate (μ max day−1) Biomass productivity (g L−1 day−1; DCW)a Maximum chlorophyll (mg L−1)
Air only 2.31 ± 0.09* 0.61 ± 0.09* 0.04 ± 0.00* 3.52 ± 1.0*
Air + 5 mM NaHCO3 3.53 ± 0.2* 0.82 ± 0.02* 0.06 ± 0.01* 5.72 ± 1.0*
Air + 5 % (v/v) CO2 pH control 14.21 ± 4.67** 0.76 ± 0.05* 0.11 ± 0.02* 8.01 ± 1.23*
5 % (v/v) CO2 continuous 23.92 ± 1.55** 1.02 ± 0.02* 0.11 ± 0.01* 8.13 ± 1.46*
Optimized scenario 5.93 ± 0.61b 1.72 ± 0.06 0.14 ± 0.00 10.7 ± 0.84
  1. Experimental conditions: (1) continuous sparge of atmospheric air, (2) continuous sparge of atmospheric air and supplemented with 5 mM NaHCO3 at inoculation, (3) continuous sparge of atmospheric air supplemented periodically with 5 % CO2 (v/v) to maintain pH between 8.4 and 8.7, (4) continuous sparge of atmospheric air supplemented with 5 % CO2 (v/v) during daytime hours, and (5) the optimized scenario of a continuous sparge of atmospheric air supplemented periodically with 5 % CO2 (v/v) to maintain pH between 8.4 and 8.7 and an initial addition of 5 mM NaHCO3 at inoculation plus an additional 50 mM NaHCO3 just prior to nitrogen depletion to stimulate TAG accumulation (n = 3). All growth yields are calculated for the exponential growth phase (i.e., from inoculation until depletion of nitrogen)
  2. * p value <0.05 as determined by a two-tailed t test, statistically significantly lower (difference between treatment and optimized scenario)
  3. ** p value <0.05 as determined by a two-tailed t test, statistically significantly higher (difference between treatment and optimized scenario)
  4. aDry cell weight (DCW) determined gravimetrically with lyophilized biomass
  5. b50 mM NaHCO3 addition results in cessation of cellular division