Direct utilization of waste water algal biomass for ethanol production by cellulolytic Clostridium phytofermentans DSM1183

•Ethanol production from non-pretreated and pretreated algal biomass using Clostridium phytofermentans DSM1183.•The ethanol production achieved was 4.6 g L−1 with acid pretreated algal biomass (2%, w/v) with solvent yield of 0.26 g/g.•Fermentation of 2% (w/v) non-pretreated algal biomass produced 0.52 g L−1 of ethanol with solvent yield of 0.19 g/g.

Direct bioconversion of waste water algal biomass into ethanol using Clostridium phytofermentans DSM1183 was demonstrated in this study. Fermentation of 2% (w/v) autoclaved algal biomass produced ethanol concentration of 0.52 g L−1 (solvent yield of 0.19 g/g) where as fermentation of acid pretreated algal biomass (2%, w/v) produced ethanol concentration of 4.6 g L−1 in GS2 media (solvent yield of 0.26 g/g). The control experiment with 2% (w/v) glucose in GS2 media produced ethanol concentration of 2.8 g L−1 (solvent yield of 0.25 g/g). The microalgal strains from waste water algal biomass were identified as Chlamydomonas dorsoventralis, Graesiella emersonii, Coelastrum proboscideum, Scenedesmus obliquus, Micractinium sp., Desmodesmus sp., and Chlorella sp., based on ITS-2 molecular marker. The presence of glucose, galactose, xylose and rhamnose were detected by high performance liquid chromatography in the algal biomass. Scanning Electron Microscopy observations of fermentation samples showed characteristic morphological changes in algal cells and bioaccessibility of C. phytofermentans.