Cell disruption of Chlorella sp. and Ecklonia maxima biomass for bioethanol production using Saccharomyces cerevisiae

The demand for bioethanol has increased over the years due to the high costs of fossil fuels, which have been associated with environmental deterioration, leading to the need for cheaper and cleaner biofuel sources. To address this issue, this study investigated micro (Chlorella sp.) and macroalgal (Ecklonia maxima) biomass cell disruption for subsequent bioethanol production using Saccharomyces cerevisiae. Different biomass concentrations of 1.25, 2.5, 3.75 and 5%w/v were prepared, and cell disrupted using ultrasonication and steam extraction for 10, 20, 30 and 40 mins. The samples were analysed for reducing sugar concentrations where the steam-extracted samples produced the highest reducing sugars of 8980 mg/L and 1800 mg/L for Chlorella sp. and E. maxima biomasses respectively. The extracts from ultrasonication and steam extraction were fermented for a period of 96 h where the steam-extracted extracts produced the highest ethanol concentrations from Chlorella sp. and E. maxima biomasses, at the maximum ethanol concentrations of 7 300 mg/L and 689.2 mg/L respectively. The findings of this paper showed that steam extraction is a preferred biomass pretreatment method since its extracts yielded higher ethanol concentrations while the ultrasonicated extracts produced lower ethanol concentrations.