Aquaculture ponds as reservoirs of freshwater microalgae with biotechnological potential: growth kinetics, biomass productivity, and biochemical profiles
Aquaculture ponds represent nutrient-rich and dynamic systems that function as reservoirs of underexplored native microalgae pre-adapted for cultivation. In this study, freshwater microalgae were isolated from Nile tilapia aquaculture ponds in São Paulo State, Brazil, and evaluated for growth kinetics, biomass productivity, biochemical composition, and FAME profiles. The isolates comprised nine chlorophytes and one cyanobacterium distributed across multiple taxonomic orders. Marked interspecific variability was observed under standardized cultivation conditions. Microcystis wesenbergii and Scenedesmus sp. exhibited the highest specific growth rates and maximum cell yields. M. wesenbergii also achieved the greatest biomass concentration (0.92 g L−1) and productivity (34.98 mg L−1 day−1). Protein was the dominant macromolecular fraction in most strains, particularly in Scenedesmus javanensis and Crucigeniella pulchra, exceeding 34% DW, highlighting their potential for protein-oriented applications. Chlorococcum sp., Kirchneriella sp., and M. wesenbergii showed the greatest carbohydrate accumulation, reaching up to 12% DW, whereas the highest lipid content was recorded for S. javanensis (14.1% DW). FAME analysis of selected strains revealed a predominance of palmitic acid among saturated fatty acids (reaching up 54.11% of total FAMEs in Kirchneriella sp.) and high proportions of polyunsaturated fatty acids, particularly γ-linolenic (reaching up to 42.10% of total FAMEs in Chlorella vulgaris), underscoring the potential of these strains for nutraceutical and functional lipid applications. Overall, freshwater aquaculture ponds harbor taxonomically and functionally diverse microalgal strains with significant biotechnological potential, as demonstrated by the integrated evaluation of their growth performance and biochemical composition, supporting these environments as strategic sources for microalgal bioprospecting.