Browsing by Author "Pereira, Ricardo Manuel Ferreira dos Santos"
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- Production of biological compounds with marine bacteriaPublication . Pereira, Ricardo Manuel Ferreira dos Santos; Carvalho, Carla da Conceição Caramujo Rocha de; Serra, Maria Celeste PereiraMarine biodiscovery is a promising field for novel compounds and materials. For the application of blue biotechnology, the development of new strategies is paramount to shorten the pipeline between enzyme and metabolite discovery and application, i.e. to increase of efficiency of the bioprocess to obtain industrial relevant yields. By understanding the mechanisms and stress conditions in the marine environment that favoured the production of a given compound by marine bacteria, high production levels of commercially interesting compounds should be achieved. The goal of this thesis was to develop a bioprocess, at laboratory scale, using marine bacteria for the production of prodiginine compound(s), which have applications in different fields including the pharmaceutical and food industries. The selected strain and product(s) were characterized using, respectively, i) 16S rRNA and lipid profile, and ii) UV-VIS, NMR, FTIR, and GC-MS techniques. Through an intense screening process in shaken flasks, using culturomics and lipidomics approaches, the growth conditions leading to the highest yields were assessed. Several parameters were evaluated, including e.g. nature of the carbon and nitrogen sources, presence of metals ions, light exposure, temperature, pH, agitation, and oxygen concentration. Additionally, the effect of specific stresses such as nutrient depletion and the growth of the cells in biofilms were also evaluated. Once the best medium composition and cultivation conditions were determined, the bioprocess was scaled up to 2 L bioreactors for further improvement of the bioprocess. The maintenance of the oxygen transfer coefficient (kLa) was used as scale-up criterion, and Büch’s, Doran’s, Michels and Miller’s Equations were firstly employed for the determination of kLa. The effect of stirring conditions, medium composition and kLa on biomass and prodiginine production was further assessed at this scale. It was found that supplementation of marine broth (MB) with appropriate nitrogen sources and metal ions increased to 200 mg/(L.h) both biomass and prodiginine productivities.