Fig 1.
Configuration of the flat-plate photobioreactor systems.
Photobioreactors used a 14 mm light path length with illumination by warm-white LED lights. Photobioreactors were set up, monitored and data-logged using a custom program running on a Linux single board computer.
Fig 2.
Cultivation data for Nannochloropsis in flat-plate photobioreactors.
(a) Growth trajectory and irradiance pattern of 16-day cultivations in high-NP and low–NP nutrient treatments. Fitted lines are from the logistic model and shaded areas indicate the standard error of the fitted values. (b) Absorbance ratio (A680/A540) of the cell suspension. (c) Broth pH and temperature. (d) Concentration of extracellular nitrate (mM∙L-1). (e) Transmitted photon flux is the photon flux exiting the rear face of the reactor.
Table 1.
Biomass properties of Nannochloropsis sp. cultivated in flat plate photobioreactors.
Fig 3.
Growth performance of Nannochloropsis.
(a) The productivity (P) was computed from the growth curves (CX, Fig 2A) with a 1 hour timestep. (b) The specific growth rate (k) was then calculated from the biomass concentration (CX) and productivity (P) over time. Lines are the treatment means.
Table 2.
Summary statistics of Nannochloropsis growth in low-NP and high-NP medium.
Table 3.
Changes in total fatty acids (mg∙g-1 dry weight) during different growth stages of Nannochloropsis cultivated at two NP concentrations.
Fig 4.
Fatty acids in the neutral lipids (TAG) of Nannochloropsis.
(a) Individual fatty acids (b) Total fatty acids. Data are mg∙g-1 dry cell weight after 8, 12 and 16 days of cultivation in low-NP medium. Data is the mean of three replicate cultivations and error bars indicate the standard deviation.
Table 4.
Percentage fatty acid composition (% total fatty acids) of Nannochloropsis neutral lipids (TAG) at three different growth phases in low-NP medium.
Fig 5.
Cell protein content vs EPA, calorific value and total fatty acids.
(a) The relationship between the percentage of protein and the percentage EPA in dry cell mass after 8, 12 and 16 days of cultivation in low-NP and high-NP treatments is described by a linear fit. (b) The relationship between the percentage of protein and the calorific value after 8, 12 and 16 days of cultivation in low-NP and high-NP treatments is described by a linear fit. (c) The relationship between the percentage protein and total fatty acids across all treatments is described by a quadratic fit (for visual guidance) where y = 0.024∙x2–2.52∙x + 75.9. Each data point is derived from a single cultivation (n = 18).