Abstract
The large-scale biomass production is an essential step in the biotechnological applications of microalgae. Coccomyxa onubensis is an acidophilic microalga isolated from the highly acidic waters of Río Tinto (province of Huelva, Spain) and has been shown to accumulate a high concentration of lutein (9.7 mg g−1dw), a valuable antioxidant, when grown at laboratory-scale. A productivity of 0.14 g L−1 d−1 was obtained by growing the microalga under outdoor conditions in an 800 L tubular photobioreactor. The results show a stable biomass production for at least one month and with a lutein content of 10 mg g−1dw, at pH values in the range 2.5–3.0 and temperature in the range 10–25 °C. Culture density, temperature, and CO2 availability in highly acidic medium are rate-limiting conditions for the microalgal growth. These aspects are discussed in this paper in order to improve the outdoor culture conditions for competitive applications of C. onubensis.
Highlights
The production of microalgal biomass efficiently is a key prerequisite in the production process of valuable compounds from microalgae
In this work we investigated the growth of the microalga in an 800 L vertically stacked tubular photobioreactor, and this creates a step forward in the way for the efficient and economically feasible production of enriched
Coccomyxa onubensis ACCV1 was isolated from the acidic waters of the Tinto river, Huelva (Spain), phylogenetically characterized and deposited in the Experimental Phycology and Culture Collection of Algae at the University of Goettingen in Germany (SAG) with the stock number SAG 2510 [15]
Summary
The production of microalgal biomass efficiently is a key prerequisite in the production process of valuable compounds from microalgae. Large-scale production of biomass requires the processing of high volume of cultures and the use of both indoor and outdoor systems, which may differ in geometry, culture engineering principles, and variable ambient conditions. Open raceway systems, and flat panel systems, have so far been widely recognized as suitable for large-scale microalgal production under outdoor conditions [3,4]. The choice of the culture system is highly influenced by the characteristics of the specific microalgal species, such as its robustness, growth rate, and the value and purity requirements of the target product to be obtained. Tubular and panel photobioreactors systems should be suitable to carry out the massive production of non-robust microalgal species, where the risk of contamination by undesired microorganisms and fluctuation of specific culture parameters, such as oxygen concentration and temperature can be Processes 2020, 8, 324; doi:10.3390/pr8030324 www.mdpi.com/journal/processes
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