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PONTIFICIA UNIVERSIDAD CATÓLICA DE CHILE (2013)

GLOEOCAPSOPSIS AAB1, A CYANOBACTERIUM HIGHL Y TOLERANT TO DESICCATION ISOLATED FROM THE ATACAMA DESERT

AZUA BUSTOS, ARMANDO JAVIER

Titre : GLOEOCAPSOPSIS AAB1, A CYANOBACTERIUM HIGHL Y TOLERANT TO DESICCATION ISOLATED FROM THE ATACAMA DESERT

Auteur : AZUA BUSTOS, ARMANDO JAVIER

Université de soutenance : PONTIFICIA UNIVERSIDAD CATÓLICA DE CHILE

Grade : DOCTOR EN CIENCIAS BIOLOGICAS MENCION GENETICA MOLECULAR Y MICROBIOLOGIA 2013

Résumé
The comprehensive study of microorganisms that evolved in the Atacama Desert, the driest and oldest on Earth, may be of help to understand the key role of water for life in general. In order to approach this aim, we first characterized the microenvironment that allows the colonization of the underside of quartzes of the Coastal range of this desert by hypolithic microorganisms. We then described the microbial diversity composition of these biofilms, later isolating a cyanobacterial isolate from them. Based on morphologic and phylogenetic analyses, this isolate (AAB1) was classified as a new member of the genus Gloeocapsopsis. Physiological, morphological and molecular changes of isolate AAB 1 cells under desiccation showed that this isolate is highly tolerant to this stressful condition. Our results indicate that isolate AAB 1 synthesizes sucrose and trehalose in response to desiccation. We identified the two candidate genes involved in sucrose synthesis (sucrose-6-phosphate synthase and sucrose-6-phosphate phosphatase). However, we could not identify the genes involved in trehalose synthesis. We then mesured the mRNA levels of the candidate genes involved in sucrose synthesis under conditions of desiccation. However, due to the variations observed, further experiments are required to really interprete the results. Finally, the results obtained suggest that isolate AAB 1 cells may be metabolically active under conditions of extreme desiccation. This possibility was preliminary confirmed by the quantification of the pools of A TP in desiccated cells, which we found varied in response to various environmental stimuli

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Page publiée le 23 février 2015, mise à jour le 10 janvier 2019