Evaluation of Microalgae: Isolation and Characterization and the Physicochemical Properties of the Osun Fish Pond

Abstract

Africa represents a relatively underexplored region concerning microalgal diversity and
biotechnological applications. Therefore, isolation and characterization of algae from this region
serve as initial steps towards prospecting high-value products. The present study aimed to isolate
and characterize microalgae associated with a fish pond in Osun state, Nigeria. Water samples were
aseptically collected from the Osun fish pond and cultured with Beneck’s medium supplemented
with growth factors using the pour plate technique. The cultures were incubated for 7 to 14 days at
room temperature (28±2 0C) under natural illumination. Pure colonies were obtained using the streak
technique. The microalgae were morphologically identified microscopically. To understand the
adaptation of microalgae to their environment, physicochemical parameters of the water samples
were analyzed using standard methods. Algae identified include Spirulina sp., Microcystis
aeruginosa, Phacus sp., Chlorella vulgaris, Scenedesmus dimorphus, Pediastrum sp., Scenedesmus
quadricauda, Euglena sp., Pinnularia sp., Closterium sp., Oscillatoria sp., Navicula sp. and
Spirogyra sp. The presence of Microcystis aeruginosa, as well as low dissolved oxygen (3.40 ppm),
indicates eutrophication of the pond, which may eventually affect fish yield. In addition, the water
quality parameters such as nitrate (0.610 mg/l) and phosphate (40.2 mg/l) are favorable for the
growth of microalgae. The microalgae isolated has a long history of biotechnological applications,
which means the next phase of prospecting will establish its potential to produce high-value
products and possibly remediation of nutrient-rich effluents.