L.M. (Mariela) Serrano MSc: “Oxidative Stress Response in Lactobacillus plantarum WCFS1: a Functional Genomics Approach”

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18 Apr 2008 11:00
Unit: Wageningen University
Location: Aula, building 362, Gen. Foulkesweg 1, Wageningen
Organisation: Wageningen University
Promotor: prof.dr. W.M. de Vos (Microbiology)
Co Promotor: Dr. E.J. Smid (NIZO Food Research, Ede)

 Control of activity and functionality of microbial starter and probiotic cultures under industrial fermentation conditions is essential in order to provide a tasty, appealing, healthy, and safe product. Oxidative stress is one of the harsh conditions that fermentative microbes have managed to endure during their use in industrial fermentation processes. A widely-used lactic acid bacterium in food fermentations is Lactobacillus plantarum. Hence, understanding oxidative stress response in this micro-organism can be used for engineering robustness towards oxidative stress. There are two systems known to be involved in oxidative stress response and redox homeostasis in bacteria: the thioredoxin and glutaredoxin systems. In this study, we constructed a set of L. plantarum WCFS1 strains with alterations in these systems. Using the constructed strains under different oxidative stress conditions (hydrogen peroxide, diamide (thiol-stress), aerobic growth, and respiratory growth), global transcriptome analysis was performed. Subsequently, the functional role of the thioredoxin- and glutaredoxin system was analyzed and validated using a number of different techniques including comparative genomics, enzyme assays, and q-PCR. The main results obtained in this study include the role of the thioredoxin system in oxidative stress response in L. plantarum as well as in adaptation to aerobic cultivation; characterization and overlap of the thioredoxin and glutaredoxin system in this bacterium; insight into transcriptome regulation of oxidative stress response, and unravelling of stress-response networks present in L. plantarum WCFS1. The comparative genomics and global transcriptome analysis of the oxidative stress response of L. plantarum WCFS1 presented in this thesis can be used for optimization of the performance of lactic acid bacteria in industrial fermentations.
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