| Summary: | In this fast-developing world, there is an increasing demand for biodegradable and renewable materials derived from cheap and wildly available resources. Waste gases from industry (steel manufacturing, oil refining, coal and natural/shale gas) can be used as alternatives to petroleum-based solutions. In this context, the development of technologies allowing us to meet new trends and demands is becoming increasingly essential.
Several microorganisms are known to have the potential to address this challenge. In particular, the model organism Cupriavidus necator H16 is able to produce naturally biodegradable thermoplastics that can be used as renewable source for the plastic industry growing the bacteria on CO2 and H2, as a sole carbon and energy source.
In this study, a dual strategy is used in an attempt to improve CO2 assimilation efficiency in C. necator H16. The first strategy involved the heterologous expression of genes for self-assembled proteinaceous organelles (a-carboxysomes) in C. necator, to observe if their carbon concentrating mechanism (CCM) boosts the carbon fixation efficiency of the organism. I have shown that it is possible to heterologously express the cso operon in C. necator, however, the functionality of the a-carboxysomes could not be confirmed. Further analysis on the mechanism driving RubisCO encapsulation in the a-carboxysomes was carried out using molecular modelling techniques. Where the surface electrostatic potential showed to play a role during the carboxysome self-assembly process. The second strategy aimed to test LysR independent and LysR dependent constitutive transcription of the cbb operons. The singular mutation of CbbR (A167V) proved to be advantageous for enhancing CO2 fixation possibly due to the constitutive expression of both cbb operons and absence of catabolite feedback.
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