Optimization of Bioethanol Production from Ceratophyllum demersum for hand sanitizers

Abstract

Hands are the primary way to spread microorganisms, thus hand washing is the primary defence and an essential element of personal hygiene for infection control. Hand sanitizers that contain ethanol as their main constituent are used to kill a broad range of microbes. Bioethanol production has relied heavily on the use of first-generation feedstock. Therefore, the development and utilization of alternative feedstocks such as weed (Ceratophyllum demersum) and other non-food crops have gained more attention in recent times. This study explores the bioethanol production using C. demersum, a weedy species, for its potential use in hand sanitizer production. The substrate, C. demersum was subjected to mechanical pre-treatment and then pre-treated with varying concentrations of sulfuric acid, which was subsequently followed by enzymatic pre-treatment and allowed for fermentation using Saccharomyces cerevisiae. The results showed that a sulfuric acid concentration of 1 M resulted in a significantly higher amount of reducing sugar and alcohol yield compared to other concentrations, and this was selected for further studies. After optimization of fermentation parameters, a significantly higher alcohol yield of 2.6% was achieved using a S. cerevisiae inoculum concentration of 100 g/l and agitation at 150 rpm at 40°C for 36 hours. Subsequent optimization of fermentation media components further increased the alcohol yield to 3.7%, with the use of 6 g/l yeast extract, 6 g/l (NH4)2SO4, 5 g/l MgSO4, and 8 g/l KH2PO4. The resulting alcohol mixture was analyzed and found to contain 84.9% bioethanol. An agar well diffusion assay was conducted against bacteria and fungi. The results showed that all the bacterial and fungal strains were sensitive to the bioethanol extract as evidenced by the presence of an inhibition zone.