Torulaspora delbrueckiiaplicaciones tecnológicas y aislamiento de genes de respuesta a estrés.

Abstract

This work is organized as a compound of five publications. On the first one we confirm that T. delbrueckii strains PYCC5321 and PYCC5323, fulfil the most important requisites of modern baking in sweet and frozen sweet doughs. We also observed that the strain PYCC5321 shows a clear phenotype of osmotolerance and Na+ toxicity resistance in synthetic media. Therefore these strain could be a good model to identify co-ordinately expressed genes under those conditions in bakers yeast. On the second part of this work we used a genomic library of the PYCC5321 strain in order to isolated the TdURA3 gene, encoding a orotidine-5-phosphate decarboxilase, and we used the sequence of these gene to construct a T. delbrueckii Ura- host strain for genetic manipulation, the FRY112 strain. Due to the potential biotechnological application of Torulaspora, we used these strain to confirm its use as a host of heterologous genes. In the last part of this work, we studied in T. delbrueckii two of the most important pathways implied in osmotolerance and ionic resistance in S. cerevisiae, the HOG pathway and the Calcineurin-Crz1p pathway. For this purpose, we have cloned the TdHOG1 gene, encoding a putative 427-amino acids protein which displayed a high degree of identity with the MAPK Hog1p of S. cerevisiae. We also cloned the TdENA1 and TdCRZ1 genes , which a putative Na+/Li+ P-Type ATPase and a zinc finger protein homologous to S. cerevisiae Crz1p. We concluded that in T. delbrueckii exists a HOG and Calcineurin-Crz1p pathways with different functional roles of S. cerevisiae.