Acetic Acid-Tolerant Native Yeast Pichia kudriavzevii ITV-S42 Isolated from Sweet Sorghum Juice for Ethanol Production

The principal desirable characteristics of the yeasts used in order to maintain the yield and the efficiency high during the process of ethanol production are mainly thermotolerance, Killer activity and high resistance to inhibitor compounds like acetic acid. Yeast represents the most important factor to achieve an efficient conversion process of the different raw materials used to produce ethanol like sorghum and sugarcane juice or their lignocellulosic materials. The aim of this work was to isolate and select native yeasts from sweet sorghum juice with thermotolerance and resistance to toxic compounds like acetic acid, furfural and 5-hydroxymethylfurfural, capable of producing high ethanol concentrations. The results obtained showed that native yeast Pichia kudriavzevii ITV-S42 exhibit thermotolerance at 40 °C, positive Killer activity, tolerant to acetic acid up to 24 g/L initial concentration, and tolerant to furfural and 5-hydroxymethylfurfural up to 1 g/L for both compounds. An ethanol productivity and yield of 0.54 g/Lh and 0.376 g ethanol/g glucose, respectively, were obtained. These results show that the desirable characteristics of Pichia kudriavzevii ITV-S42 could be interesting for their implementation in first and second generation ethanol process production.