title: Genetic and transcriptional study of glutathione metabolism in Oenococcus oeni.
abstract: Although Oenococcus oeni is the main species that is responsible for malolactic fermentation (MLF), harsh wine conditions can limit its performance. Although several mechanisms underlying the response to stress have been studied in this species, little is known regarding the cellular systems that protect against oxidative stress in other bacteria, such as glutathione (GSH). O. oeni cannot synthesize GSH but contains several genes related to its utilization. In this study, the relative expression (RE) of the seven genes involved in the GSH redox system found in O. oeni PSU-1 (gshR, gpo, three glutaredoxin-like genes and two subunits of an hypothetical transporter) has been measured. The study was performed using three strains, with each exhibiting a different GSH uptake capacity. The strains were grown in a stress-adaptation medium supplemented with 5mM GSH and under different adaptation stress conditions (pH4 and 6% ethanol). The RE showed that only some of these genes, including one for a possible glutaredoxin (OEOE_RS04215) and cydC for a subunit of a putative GSH transporter (OEOE_RS1995), responded to the addition of GSH. The presence of ethanol had a relevant effect on gene expression. Among the studied genes, the one for a NrdH-redoxin (OEOE_RS00645) showed a common response to ethanol in the strains, being over-expressed when grown with GSH. In most cases, the transcriptional changes were more evident for the strain with a higher capacity of GSH uptake. Malolactic performance of the three strains after pre-adaptation was evaluated in wine-like media (12% ethanol and pH3.4). It was observed that the addition of GSH during pre-adaptation growth had a protective role in the cells exposed to low pH and ethanol, resulting in a quicker MLF.
authors.affiliation: Grup de Biotecnologia Enològica, Departament de Bioquímica i Biotecnologia, Facultat d'Enologia, Universitat Rovira i Virgili, Marcel·lí Domingo, 1, 43007 Tarragona, Catalonia, Spain.
authors.forename: Mar
authors.initials: M
authors.lastname: Margalef-Català
authors.affiliation: Grup de Biotecnologia Enològica, Departament de Bioquímica i Biotecnologia, Facultat d'Enologia, Universitat Rovira i Virgili, Marcel·lí Domingo, 1, 43007 Tarragona, Catalonia, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Araque
authors.affiliation: Grup de Biotecnologia Enològica, Departament de Bioquímica i Biotecnologia, Facultat d'Enologia, Universitat Rovira i Virgili, Marcel·lí Domingo, 1, 43007 Tarragona, Catalonia, Spain.
authors.forename: Albert
authors.initials: A
authors.lastname: Bordons
authors.affiliation: Grup de Biotecnologia Enològica, Departament de Bioquímica i Biotecnologia, Facultat d'Enologia, Universitat Rovira i Virgili, Marcel·lí Domingo, 1, 43007 Tarragona, Catalonia, Spain. Electronic address: cristina.reguant@urv.cat.
authors.forename: Cristina
authors.initials: C
authors.lastname: Reguant
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D005978:Glutathione / Q000378:metabolism*; D056585:Oenococcus / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014920:Wine / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; D000431:Ethanol; D005978:Glutathione
keywords: Glutaredoxin; Glutathione; Malolactic fermentation; NdrH; Oenococcus oeni; qPCR