Identification and characterization of four microalgae strains with potential application in the treatment of tail-water for shrimp cultivation

A microalgae-based water treatment system can not only remove pollutants but also produce live bait or feed additives for aquatic animals. To obtain microalgae strains suitable for local conditions, four microalgae were isolated from a shrimp breeding pond in Changjiang, Hainan, China. The microalgae were cultured under different conditions and the results showed that MA001 and MA004 adapted to a wide range of temperature (25 °C, 30 °C and 35 °C), salinities (fresh water, 10 ‰, 20 ‰, 30 ‰ and 100 ‰) and light intensities (~100 μmol m−2 s−1, ~200 μmol m−2 s−1, ~400 μmol m−2 s−1). Cultivation with organic carbon sources revealed that glucose promoted the growth of MA001 and MA004, acetate promoted the growth of MA002 and MA004. MA002 was intolerant to glucose, and MA005 was intolerant to acetate. Furthermore, shrimp culture feed degraded liquid (FL1) significantly promoted the growth of these four microalgae, whereas molasses broth fermented by Bacillus (FL2) significantly promoted the growth of MA001, MA002 and MA004 but not of MA005. However, MA002 cultured with FL1 and MA005 cultured with FL2 significantly increased protein content in cells than those cultured with BG11. All microalgae strains in different culture mediums removed NH4+-N up to 95.49 %–100.00 %. The removal efficiency of PO43−-P by MA005 in FL1 and FL2 were >80 %, which were significantly higher than in BG11. Our results indicated these algal strains had different optimal growth conditions and substrate preferences and had potential application in the construction of an microalgae-based RAS water treatment system in Hainan.