A comparative study on the productivity of selected tropical freshwater microalgae

Abstract

The wide spread use of microalgae in various fields of human activity including fishery generated a need of screening of highly productive microalgae. Therefore, in this study, grow rate and productivity of selected freshwater microalgae species (Nephrocytium sp., Nannochloropsis sp., Selenastrum sp., Sphaerocystis sp., Ankistrodesmus sp., Monoraphidium sp., Pectinodesmus sp. and Scenedesmus sp.) were studied. Selected microalgae were cultured in Bold Basal Medium and cell density was determined to analyze specific growth rate (SGR), cell duplication time and cell doublings per day. In addition, biomass data and lipid data were recorded to calculate volumetric, areal and lipid productivity. Results showed that Monoraphidium sp. had significantly highest (p<0.05) SGR in lag phase (0.861±0.017/day) and exponential phase (0.437±0.016/day) where Ankistrodesmus sp. showed significantly highest (p<0.05) SGR in stationary phase (0.221±0.009/day) compared to others. Selenastrum sp. and Scenedesmus sp. showed significantly (p<0.05) highest and lowest cell duplication time and cell doublings per day was highest in Monoraphidium sp. Volumetric (47.738±0.576 mg/L/Day) and areal (4.774±0.058 mg/cm2/day) productivity were significantly (p<0.05) highest in Scenedesmus sp. but lipid productivity was in Monoraphidium sp. (8.513±0.258 mg/L/Day). This study concluded that Monoraphidium sp. performed best and accumulated much higher lipid in a day in BBM which will contribute to produce biomass that can be utilized for different commercial application. Keywords: Freshwater microalgae, SGR, Cell duplication time, Cell doublings per day