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

Table 4 C. vulgaris lipid characteristics for cultures grown under various inorganic carbon regimes

Treatment	C16:0^a	C16:1^a	C18:0^a	C18:1^a	C18:2^a	C18:3^a	Other^b	Total biodiesel potential (%)^c	Potential biodiesel productivity (g L⁻¹ day⁻¹)^c
Optimized Scenario	10.66 ± 0.3	2.76 ± 0.03	5.17 ± 0.09	24.42 ± 0.44	7.17 ± 0.14	10.21 ± 0.33	0.64 ± 0.06	61.04 ± 1.31	0.098 ± 0.002
50 mM NaHCO₃∙Na₂CO₃	9.27 ± 0.34	2.64 ± 0.1	3.97 ± 0.11	19.85 ± 1.2	6.56 ± 0.18	8.45 ± 0.15	0.68 ± 0.09	51.41 ± 2.14^*	0.07 ± 0.005^*
5 % (v/v) CO₂ Continuous	9.45 ± 0.7	1.85 ± 0.14	2.36 ± 0.2	26.59 ± 2.1	4.58 ± 0.4	7.88 ± 0.76	0.63 ± 0.12	53.33 ± 1.35^*	0.091 ± 0.005^*

Experimental conditions: (1) 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 of ACS grade NaHCO₃ just prior to nitrogen depletion to stimulate TAG accumulation. (2) The same culture conditions as scenario 1 listed above, except TAG accumulation was induced by adding 25 mM NaHCO₃∙Na₂CO₃ (sesquicarbonate). (3) Continuous sparge of atmospheric air supplemented with 5 % CO₂ (v/v) during daytime hours (n = 3). Biodiesel productivity is calculated for the stationary growth phase (e.g., from depletion of nitrogen until termination of experiment)
^* p value <0.05 as determined by a two-tailed t test, statistically significantly lower (difference between treatment and optimized scenario)
^aAll values expressed as weight percent (% weight FAME/weight biomass)
^bSum of other compounds detected
^cTotal FAMEs

ISSN: 2731-3654