A pilot study assessing a nano-based commercial culture medium for microalgal mono- and polyculture

Microalgae are cell factories rich in biochemicals that can be used as a feedstock for applications such as medicines, nutraceuticals, food, feed and bioenergy. Developing economical and efficient cultivation media is a major challenge in microalgal biomass production, as efficient upstream cultivation processes are crucial for continuous biomass resource supply. Nano-based fertilisers are being developed and currently used in agricultural cultivation for greater efficacy compared to conventional chemical fertilisers. Use of nanotechnology in microalgal biotechnology is in its infancy, and use of nano-based media for microalgal cultivation is yet to be explored. In this study, a novel nano-based cultivation medium named nano-JAPH medium was formulated and standardized. The efficacy of nano-JAPH medium was tested at different nutrient concentrations and validated through laboratory-scale trials with the microalgae, Chlorella vulgaris, Chlorococcum humicola, Oocystis crassa, Scenedesmus quadricauda and Synechococcus aeruginosus. The pilot-scale outdoor trials using nano-JAPH medium were carried out subsequently with Chlorella vulgaris in a suspended cultivation system and with a polyculture microalgal consortium in an immobilized cultivation system against modified NMR commercial medium as control. The results showed that nano-JAPH medium resulted in significantly higher areal biomass productivity (10.545 g m‒2 d‒1 in suspended and 2.9 g m‒2 d‒1 in attached systems) compared to those in control with 42.3% and 13.2% increase, respectively. This study shows that the novel nano-JAPH medium can be effectively used to increase microalgae biomass productivity and facilitate commercial microalgae mass culture through sustained supply of nutrients.