Arecanut husk waste is most abundant renewable energy source that may be considered as potential feedstock for ethanol production by microbial fermentation. The arecanut husk waste was initially subjected to microbiological pretreatment for obtaining reducing sugars. Such treated substrates with and without obtaining the filtrate were further subjected to fermentation. Among these, filtrate fermentation showed maximum production of ethanol and Zymomonas mobilis was efficient in conversion to ethanol from the substrate. The maximum ethanol yield was observed in Aspergillus niger and Phanerochaete chrysosporium pretreated raw material. After pretreatment, the filterate was collected and treated with different yeast strains and Zymomonas mobilis. The minimum ethanol yield was observed in Candida shehatae (1.3 ± 0.10 mg/g) and the maximum ethanol yield was observed in Saccharomyces uvarum (4.8 ± 0.05 mg/g) treatment. The medium ethanol yield was observed in Phanerochaete chrysosporium pretreated raw material. The minimum ethanol yield was observed in Saccharomyces cerevisiae (2.0 ± 0.10 mg/g) and the maximum ethanol yield was observed in Pichia stipitis (5.3 ± 0.05 mg/g) treatment. The minimum ethanol yield was observed in Aspergillus niger pretreated raw material. The minimum ethanol yield was observed in Schizosaccharomyces pombe and Zymomonas mobilis (1.4 ± 0.10 mg/g) and the maximum ethanol yield was observed in Saccharomyces uvarum (2.9 ± 0.05 mg/g) treatment. When both fermentation methods were compared, maximum ethanol was produced in filtrate fermentation method (without solids). It is essential to identify better combination of pretreatment methods and efficient yeast strains for exploiting the arecanut husk waste for ethanol production.
