High-temperature ethanol production using thermotolerant yeast newly isolated from Greater Mekong Subregion

Abstract

The application of high-potential thermotolerant yeasts is a key factor for successful ethanol production at high temperatures. Two hundred and thirty-four yeast isolates from Greater Mekong Subregion (GMS) countries, i.e., Thailand, The Lao People's Democratic Republic (Lao PDR) and Vietnam were obtained. Five thermotolerant yeasts, designated Saccharomyces cerevisiae KKU-VN8, KKU-VN20, and KKU-VN27, Pichia kudriavzevii KKU-TH33 and P. kudriavzevii KKU-TH43, demonstrated high temperature and ethanol tolerance levels up to 45 °C and 13% (v/v), respectively. All five strains produced higher ethanol concentrations and exhibited greater productivities and yields than the industrial strain S. cerevisiae TISTR5606 during high-temperature fermentation at 40 °C and 43 °C. S. cerevisiae KKU-VN8 demonstrated the best performance for ethanol production from glucose at 37 °C with an ethanol concentration of 72.69 g/L, a productivity of 1.59 g/L/h and a theoretical ethanol yield of 86.27%. The optimal conditions for ethanol production of S. cerevisiae KKU-VN8 from sweet sorghum juice (SSJ) at 40 °C were achieved using the Box–Behnken experimental design (BBD). The maximal ethanol concentration obtained during fermentation was 89.32 g/L, with a productivity of 2.48 g/L/h and a theoretical ethanol yield of 96.32%. Thus, the newly isolated thermotolerant S. cerevisiae KKU-VN8 exhibits a great potential for commercial-scale ethanol production in the future.

Matrices (re)loaded: Durability, viability, and fermentative capacity of yeast encapsulated in beads of different composition during long‐term fed‐batch culture

“…104,105 Thus, a more thermotolerant yeast could improve the efficiency of this step. 106 To discover whether certain encapsulation matrices offer more protection against thermal stress than others, yeast were subjected to heat shock at 50 C for 180 min. Planktonic cells, in either exponential or stationary phase, as well as cells encapsulated in each of four matrices, were exposed to 50 C for 5, 15, 30, 90, and 180 min ( Figure 6), after which viability was assessed as CFUs following dilution and plating on rich agar.…”

“…,105 Thus, a more thermotolerant yeast could improve the efficiency of this step 106,107. Moreover, since cooling costs for fermentation tanks can be costly in the summer, especially in warmer regions, 108 a more thermotolerant yeast could also help reduce cooling costs, and is thus doubly favored.…”

Preliminary evaluation of sensitivity of <i>Saccharomyces cerevisiae</i> LC 269108 to thermal and ethanol stresses in fermentation of agro-wastes for bioethanol production

“…2) in this study. Such discrepancy in ethanol concentrations might result from genetic variability, differences in inoculum concentration or chemistry of the feedstock (Techaparin, 2017).…”

Potential of Thermotolerant Ethanologenic Yeasts Isolated from ASEAN Countries and Their Application in High- Temperature Fermentation

“…Auesukaree et al [51] reported a strain C3867 that produced 38.8 g/L of ethanol at 41°C. Recently, Nuanpeng et al [52] and Techaparin et al [53] isolated S. cerevisiae DBKKUY-53 and KKU-VN8, respectively, in Thailand. The former strain produced the maximum ethanol concentration and volumetric ethanol productivity of 85.0 g/L and 2.83 g/L h, respectively, at 40°C, and the latter strain produced the maximum ethanol concentration of 89.3 g/L with a productivity of 2.48 g/L h and a theoretical ethanol yield of 96.3% from sweet sorghum juice at 40°C.…”