Freshwater microalgae Desmodesmus brasiliensis, Mychonastes timauensis, and Mychonastes ovahimbae as excellent microalgae candidates for sustainable live feeds with high-value bioactive compounds

Abstract

Exploring high-value natural antioxidants from microalgae as feasible live feeds in aquaculture is receiving worldwide attention. Yet, limited microalgae species have been entirely studied for aquaculture production, especially freshwater microalgae for their antioxidant properties. Three freshwater microalgae, Desmodesmus brasiliensis (PHG C02), Mychonastes timauensis (PHG E02), and Mychonastes ovahimbae (PHG F04) were screened for their phytochemicals (chlorophylls a and b, total carotenoids content, TCC; total flavonoids content, TFC, and total phenolic content, TPC), enzymatic antioxidants (Superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX and guaiacol peroxidase, GPX) as well as non-enzymatic antioxidants (ascorbic acid, AA and α-tocopherol, α-TOC) at the early stationary phase. The results unveiled that the phytochemical and antioxidant activities responded diversely in the selected species. D. brasiliensis achieved the highest Chl a, Chl b, and TCC contents, whereas M. timauensis recorded the highest TFC and TPC contents. Significant differences in AA and α-TOC contents were observed in M. timauensis and D. brasiliensis for non-enzymatic antioxidants, respectively. In contrast, SOD and GPX reached the maximum activities in M. ovahimbae. A significant upsurge of CAT was spotted in D. brasiliensis. However, APX activity was elevated in M. timauensis and M. ovahimbae. D. brasiliensis attained most of the notably highest phytochemical and antioxidant activities, suggesting that D. brasiliensis has the potential for sustainable live feeds with high-value bioactive compounds.