Using ozone for microalgal cell disruption to improve enzymatic saccharification of cellular carbohydrates

In this study, ozone was used as a pretreatment method to improve the yield in enzymatic saccharification of microalgal carbohydrates by increasing the disruption of microalgal cells. Different ozone doses (0.25-2.0 g O-3 g(-1) dry weight biomass (DWB)) were applied to the algal suspensions before the enzymatic hydrolysis process, which was performed at various enzyme concentrations, enzymatic hydrolysis times and biomass concentrations. The highest glucose yield obtained was 80.6% (w/w) of total carbohydrates under the conditions of 2.5 g L-1 biomass concentration and 4 h hydrolysis time for 0.5 g O-3 g(-1) DWB ozone dose and 1.2 mL(-1) g(-1) DWB enzyme concentration. In addition to ozone pretreatment, the same algal culture was subjected to acid, alkaline and ultrasonic pretreatments. It was observed that application of ozone increased the glucose yield much higher than the other three pretreatment methods, indicating its great potential in production of bioethanol from microalgae. (C) 2017 Elsevier Ltd. All rights reserved.