Metabolic engineering of Cupriavidus necator for L-arginine production

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Engineered strains of Corynebacterium glutamicum and Escherichia coli are the workhorses of fermentative amino acid production, a growing industry worth billions. Yet these fermentations rely upon carbon from first-generation biomass feedstocks, which fluctuate in cost and supply.The production of palm oil generates over 30 million tons of carbon-rich waste each year. Together with current methods of fertilisation, these are responsible for at least a third of palm oil greenhouse gas emissions; the equivalent of 60 million tonnes of carbon dioxide.This polluting waste has the potential to be used as a novel feedstock for amino acid fermentation; specifically nitrogen-rich arginine, which is growing in use as a tree fertiliser. Doing so would valorise the waste by recycling its carbon back into plantations, whilst reducing the need for inorganic fertilisers. However, no industrial strain exists for this process.To this end, we aim to engineer a microbial cell factory for the conversion of carbon dioxide to L-arginine. Cupriavidus necator can naturally grow on carbon dioxide and hydrogen, making it an ideal host chassis for this purpose. Using metabolic engineering and synthetic biology strategies, an L-arginine overproducer will be developed and optimised. This will be supported by a complementary range of -omic analyses to provide novel insight into how the biosynthetic pathway is regulated. Once economically viable yields and productivities have been reached, this strain will then be demonstrated at pilot-scale gas fermentation using carbon dioxide as the feedstock.