Protein potential of Desmodesmus asymmetricus grown in greenhouse as an alternative food source for aquaculture.

Abstract

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 5days 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 ± 1.0mg L-1day-1) and July (43.3 ± 0.1mg L-1day-1); while the highest values ​​were greater than 70mg L-1day-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 ± 0.43g 100g-1), followed by aspartic acid (3.36 ± 0.23g 100g-1), while the lowest values were for methionine (0.55 ± 0.21g 100g-1), histidine (0.77 ± 0.07g 100g-1) and tyrosine (1.01 ± 0.17g 100g-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.