Ethanol production from seaweed extract

Extracts from Laminaria hyperborea could possibly be fermented to ethanol c ommercially. In particular, seaweed harvested in the autumn contains high l evels of easily extractable laminaran and mannitol, Four microorganisms wer e tested to carry out this fermentation, one bacterium and three yeasts. On ly Pichia angophorae was able to utilise both laminaran and mannitol for et hanol production, and its substrate preferences were investigated in batch and continuous cultures. Laminaran and mannitol were consumed simultaneousl y, but with different relative rates. In batch fermentations, mannitol was the preferred substrate. Its share of the total laminaran and mannitol cons umption rate increased with oxygen transfer rate (OTR) and pH, In continuou s fermentations, laminaran was the preferred substrate at low OTR, whereas at higher OTR, laminaran and mannitol were consumed at similar rates. Optim isation of ethanol yield required a low OTR, and the best yield of 0.43 g e thanol (g substrate)(-1) was achieved in batch culture at pH 4.5 and 5.8 mm ol O-2 l(-1) h(-1). However, industrial production of ethanol from seaweed would require an optimisation of the extraction process to yield a higher e thanol concentration.