Simultaneous saccharification and fermentation of ethanol from potato waste by co-cultures of Aspergillus niger and Saccharomyces cerevisiae in biofilm reactors

- Ethanol was produced in biofilm reactors by A. niger and S. cerevisiae.
- Plastic composite supports were employed for promoting biofilm formation of co-culture.
- Optimum conditions for maximum ethanol production in biofilm reactor were pH 5.8, 35 °C, and no aeration.
- Max ethanol production of 37.93 g/L was achieved with 0.41 g etoh /g starch yield.

Novel approaches for bioethanol production from industrial wastes have gained attention due to not only maximize the ethanol production productivity, but also reduce the production cost. Part of the production cost includes cost of the enzymes needed for saccharification step during the starch hydrolyzation, which can be significant cost depending on the enzymes' performances. Therefore, in this study, simultaneous saccharification and fermentation (SSF) of ethanol by co-cultures of Aspergillus niger and Saccharomyces cerevisiae was assessed in a potato waste based medium by using biofilm reactors. The plastic composite supports (PCS) were studied for biofilm formation. Effects of temperature, pH, and aeration rates in biofilm reactors were evaluated by response surface methodology and the optimal conditions were found to be 35 °C, pH 5.8, and no aeration. The maximum ethanol concentration of 37.93 g/L was achieved at the end of 72 h fermentation, with a 0.41 g ethanol/g starch yield. Finally, biofilm formation of co-culture on PCS was also evaluated by scanning electron microscope. In conclusion, the results demonstrated that PCS can be utilized for SSF processes for ethanol production in biofilm reactors with co-cultures by using starchy industrial wastes.

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