Statistical optimization of co-cultured microalgae via Plackett-Burman Design and Response Surface Methodology for bioethanol production

In microalgal bioprocessing, co-cultivation techniques provide a viable way to get around the drawbacks of monocultures. In order to improve the buildup of carbohydrates and lipids for the enrichment of biochemical content, a co-culture of Chlorella vulgaris and Chlorococcum sp. was statistically optimised, which was later used for bioethanol production. Six culture parameters were initially screened using Plackett Burman Design(PBD), and the important variables were found to be NaNO3 concentration, K2HPO4 concentration, light–dark cycle, and incubation duration. Central Composite Design (CCD) under Response Surface Methodology(RSM) has been used to further optimise these variables. With an increased lipid content of 32.1% and an increased carbohydrate content of 56%, the optimised conditions increased the yields. After 1.2 g L−1 of biomass was produced under ideal circumstances, it was hydrolysed and fermented to produce ethanol. The optimised biomass yielded 0.08 g ethanol g−1 dry biomass following hydrolysis and fermentation, demonstrating the suitability of the co-culture as a renewable substrate for bioethanol production. The results show that statistical optimisation greatly enhances algal co-cultures’ bioenergy potential and emphasise their suitability for producing renewable ethanol.