Fermentation study on Saccharina latissima for bioethanol production considering variable pre-treatments

Climate change, fuel security and economics are creating a requirement for alternative, renewable fuels. Bioethanol is currently produced from land-based crops but in future marine biomass could be used as an alternative biomass source for bioethanol production. Macroalgae such as Laminaria spp. grow in abundance around the United Kingdom, reaching >4 m in length and containing up to 55% dry weight of the carbohydrates laminarin and mannitol. Using enzymes, these can be hydrolysed and converted to glucose and fructose, which in turn can be utilised by yeasts to produce ethanol. In previous studies on ethanol production from macroalgae, pre-treatment was at 65°C, pH 2 for 1 h prior to fermentation. This paper shows that these pre-treatments are not required for the fermentations conducted, with higher ethanol yields being achieved in untreated fermentations than in those with altered pH or temperature pre-treatments. This result was seen in fresh and defrosted macroalgae samples using Saccharomyces cerevisiae and 1 U kg−1 laminarinase.