Caracterização fisiológica e metabólica de diferentes cepas de cianobacterias

• Autor(a) principal: Ferreira, Alberto Abrantes Esteves
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://www.locus.ufv.br/handle/123456789/9929
• topic: CianoBactérias - Fisiologia; CianoBactérias - Metabolismo; Fisiologia Vegetal

This is the first work to explore in details how natural variation in terms of morphology may be related to changes in growth, physiology and metabolism in cyanobacterial strains. Cyanobacterias are photosynthetic microorganisms that occupy diverse ecological niches and exhibit enormous diversity in terms of their habitats, physiology, morphology and metabolic capabilities. Accordingly, there is a growing interest for exploring these microorganisms for biotechnological applications. However, our knowledge concerning natural variation within different cyanobacteria strains in regard to metabolism is little and in general fragmented. In the present work, 18 cyanobacteria strains were used. These strains were separated in three groups based on morphological characters namely unicellular cyanobacteria, non-heterocystous cyanobacterial filaments and heterocystous cyanobacterial filaments. Higher growth in some strains was closely associated with: (i) an increased light absorption efficiency and use, reflecting directly on increments in net assimilation (A); (ii) a lower energetic requirement alongside dark respiration (R d ) and nitrogen fixation; and (iii) an adequate balance between A, R d and nitrogen fixation impacting the relative growth rate (RGR), daily biomass productivity and reserve accumulation (e.g. proteins, carbohydrates and lipids). In summary, it was observed a large potential of unicellular cyanobacterial strains for biomass, total soluble carbohydrates and lipids production, whereas non- heterocystous cyanobacterial strains were identified as promising protein producers. Although heterocystous cyanobacterial strains did not presented higher productivity of any evaluated reserves, these strains have an intrinsic potential for hydrogen production. Moreover, multivariate analysis revealed that physiological, metabolic and growth comparisons are consistent with previous morphological comparison. It is reasonable to assume that the morphological changes presented by the cyanobacterial strains used culminated in physiological, metabolic, and growth related changes. Furthermore, the results obtained demonstrate the importance of an extensive physiological and metabolic characterization within this phylum for a better understanding of metabolic relationships and selection of strains with higher potential for biotechnological applications.