The fermentation at high temperatures using thermotolerant/thermophilic microorganisms also has additional advantage on air/gas stripping. Chen et al. (2014) claimed that the gas stripping removed the ethanol inhibition with enhanced mass and heat transfer in solid-state fermentation. However, the con- tinuous ethanol fermentation with gas stripping puts on the additional costs of gas compression and recycling (Todri et al., 2014).