The ability of Pichia kudriavzevii to tolerate multiple stresses makes it promising for developing improved bioethanol production processes

Abstract

Thermotolerant ethanol fermenting yeasts have been extensively used in industrial bioethanol production. However, little is known about yeast physiology under stress during bioethanol processing. This study investigated the physiological characteristics of the thermotolerant yeast Pichia kudriavzevii, strains NUNS‐4, NUNS‐5 and NUNS‐6, under the multiple stresses of heat, ethanol and sodium chloride. Results showed that NUNS‐4, NUNS‐5 and NUNS‐6 displayed higher growth rates under each stress condition than the reference strain, Saccharomyces cerevisiae TISTR5606. Maximum specific growth rates under stresses of heat (45°C), 15% v/v ethanol and 1·0 M sodium chloride were 0·23 ± 0·04 (NUNS‐4), 0·11 ± 0·01 (NUNS‐5) and 0·15 ± 0·01 h–1 (NUNS‐5), respectively. Morphological features of all yeast studied changed distinctly with the production of granules and vacuoles when exposed to ethanol, and cells were elongated under increased sodium chloride concentration. This study suggests that the three P. kudriavzevii strains are potential candidates to use in industrial–scale fermentation due to a high specific growth rate under multiple stress conditions. Multiple stress‐tolerant P. kudriavzevii NUNS strains have received much attention not only for improving large‐scale fuel ethanol production, but also for utilizing these strains in other biotechnological industries.

Effects of Pichia kudriavzevii on development, larval mortality and adult fecundity of Zaprionus indianus (Diptera: Drosophilidae) at different temperatures.

“…This may be due to the low association frequency of P. kudriavzevii found with local population of Z. indianus from other geographical locations of Solan and Shimla having T avg equal to 21.3•C and 17.6•C, respectively, as the optimum growth temperature for P. kudriavzevii ranges from 30•C-45•C. Though, microbial pathogens have the ability to thrive under a broad spectrum of temperature, radiation and pH inhabiting diverse range of hosts(Yamagishi et al 2018), studies also supports the thermo-tolerant property of various strains of P. kudriavzevii as it can bear thermal stress as high as 45°C(Chamnipa et al 2018;Choi et al 2017;Pongcharoen 2022). The literature provides evidence of the association of various species of Pichia with the larvae of Queensland fruit y (Q y), Bactrocera tryoni(Majumder et al 2020), Drosophila suzukii(Hamby et al 2012) and from eggs of Mexican Fruit Fly, Anastrepha ludens(Salas et al 2018) with a relative abundance of around 43% (most abundant and ubiquitous), but the temperature-dependent studies of P. kudriavzevii with fruit y species are scarce.…”