Physiology of the fuel ethanol strain Saccharomyces cerevisiae PE‐2 at low pH indicates a context‐dependent performance relevant for industrial applications

This study investigates the physiology of S. cerevisiae strain PE‐2, widely used in the Brazilian fuel ethanol industry, in comparison with CEN.PK113‐7D, a reference laboratory strain, focusing on tolerance to low pH and acetic acid stress. Both strains were grown in anaerobic bioreactors, operated as batch, chemostat or dynamic continuous cultures. Despite their different backgrounds, biomass and product formation by the two strains were similar under a range of conditions (pH 5 or pH < 3, with or without 105 mM acetic acid added). PE‐2 only displayed a remarkably higher fitness than CEN.PK113‐7D during batch cultivation on complex YPD medium at low pH (2.7). Kinetics of viability loss of non‐growing cells, incubated at pH 1.5, indicated a superior survival of glucose‐depleted PE‐2 cells, when compared to either CEN.PK113‐7D or a commercial bakers’ strain. These results indicate that the sulfuric acid washing step, used in the fuel ethanol industry to decrease bacterial contamination due to non‐aseptic operation, might have exerted an important selective pressure over the microbial populations present in such environments. This article is protected by copyright. All rights reserved.
Source: FEMS Yeast Research - Category: Research Authors: Tags: Research Paper Source Type: research