Browsing by Author "Claudino, Ricardo"
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- Insights into Polyhydroxyalkanoates (PHAs) in Extremophile Microorganisms: Search for PHA-related genes and PHA accumulation in members of the genus RubrobacterPublication . Claudino, Ricardo; Egas, Conceição; Galvão, Helena Maria Leitão DemignéThis thesis investigates the potential of polyhydroxyalkanoates (PHAs) production by extremophile microorganisms. PHA offers advantages over conventional fossil-fuel-based plastics due to their biodegradability and bio-based origin. Among extremophiles capable of producing PHA, species of the genus Rubrobacter are promising contenders and were chosen for this investigation. The research involved a bioinformatic analysis of Rubrobacter genomes, specifically examining the presence of key genes (phaA, phaB, phaC) belonging to the PHA synthesis pathway. Since only some of the species studied possess the class I PHA synthase, suggested potential differences in PHA synthesis capabilities. Further investigation into the phaC lipase box-like motif, pointed to variations in their conserved region which may also impact the capacity of PHA synthesis by different Rubrobacter species. The synthesis of PHA was then tested experimentally. Thermus medium emerged as the most suitable to grow the organisms and to standardize experimental conditions. Potentiation of PHA accumulation was achieved in a minimal medium supplemented with glucose as a carbon source. With the Sudan Black B method, it was possible to identify the Rubrobacter xylanophilus DSM 9941T, Rubrobacter radiotolerans RSPS-4 and Rubrobacter radiotolerans DSM 5868T species as PHA accumulators. Confirmation of PHA accumulation was achieved through transmission electron microscopy and an indirect PHA detection method. Notably, the presence of the class I PHA synthases in the studied species correlated with successful PHA production, emphasizing its significance and concluding an identification of a link between genomic characteristics and phenotypic outcomes in PHA synthesis within the thermophilic Rubrobacter species studied. Future research should include exploring the specific types of PHA produced by different species and assessing economic viability based on production costs and market demand, which is crucial for commercial use.