title: Catalase overexpression reduces lactic acid-induced oxidative stress in Saccharomyces cerevisiae.
abstract: Industrial production of lactic acid with the current pyruvate decarboxylase-negative Saccharomyces cerevisiae strains requires aeration to allow for respiratory generation of ATP to facilitate growth and, even under nongrowing conditions, cellular maintenance. In the current study, we observed an inhibition of aerobic growth in the presence of lactic acid. Unexpectedly, the cyb2Delta reference strain, used to avoid aerobic consumption of lactic acid, had a specific growth rate of 0.25 h(-1) in anaerobic batch cultures containing lactic acid but only 0.16 h(-1) in identical aerobic cultures. Measurements of aerobic cultures of S. cerevisiae showed that the addition of lactic acid to the growth medium resulted in elevated levels of reactive oxygen species (ROS). To reduce the accumulation of lactic acid-induced ROS, cytosolic catalase (CTT1) was overexpressed by replacing the native promoter with the strong constitutive TPI1 promoter. Increased activity of catalase was confirmed and later correlated with decreased levels of ROS and increased specific growth rates in the presence of high lactic acid concentrations. The increased fitness of this genetically modified strain demonstrates the successful attenuation of additional stress that is derived from aerobic metabolism and may provide the basis for enhanced (micro)aerobic production of organic acids in S. cerevisiae.
authors.affiliation: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
authors.forename: Derek A
authors.initials: DA
authors.lastname: Abbott
authors.forename: Erwin
authors.initials: E
authors.lastname: Suir
authors.forename: Giang-Huong
authors.initials: GH
authors.lastname: Duong
authors.forename: Erik
authors.initials: E
authors.lastname: de Hulster
authors.forename: Jack T
authors.initials: JT
authors.lastname: Pronk
authors.forename: Antonius J A
authors.initials: AJ
authors.lastname: van Maris
mesh_terms: D000332:Aerobiosis; D002374:Catalase / Q000096:biosynthesis* / Q000235:genetics; D019344:Lactic Acid / Q000378:metabolism*; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000633:toxicity; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000201:enzymology* / Q000254:growth & development / Q000502:physiology*
chemical_list: D017382:Reactive Oxygen Species; D019344:Lactic Acid; D002374:Catalase