During ten months, batch culture of Desmodesmus asymmetricus microalgae was carried out under greenhouse conditions. The inoculation ratio was 1:1 (inoculum:treated water). The cultures were maintained for 5 days with natural light and constant aeration mixed with carbon dioxide. The biomass was concentrated by centrifugation and dried by lyophilization; subsequently, total proteins and amino acid concentration were quantified. A relationship between biomass production and seasonal variation was observed, the lowest dry biomass production was recorded in June (38.8 ± 1.0 mg L-1 day-1) and July (43.3 ± 0.1 mg L-1 day-1); while the highest values were greater than 70 mg L-1 day-1 in March. There was a high positive correlation between wet and dry biomass (r = 0.97, p < 0.001) with a mean conversion of 26%. The mean percentage of protein was 26.1 ± 2.6%, the highest percentage was registered in March (31.03 ± 1.48%) as well as the concentration of amino acids. Regarding amino acids, arginine obtained the highest concentration (4.08 ± 0.43 g 100 g-1), followed by aspartic acid (3.36 ± 0.23 g 100 g-1), while the lowest values were for methionine (0.55 ± 0.21 g 100 g-1), histidine (0.77 ± 0.07 g 100 g-1) and tyrosine (1.01 ± 0.17 g 100 g-1). Finally, according to the essential amino acid index (in fish ≥ 0.90, in crustaceans > 0.80), the biomass of D. asymmetricus has potential as a food supplement for the production of feed in aquaculture.
Keywords: Biomass; Bioreactor; Desmodesmus asymmetricus; Essential amino acids index; Total protein.
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