The wise use of abundant renewable lignocellulose (LC) as a carbon source for the bioproduction of chemicals will reduce our dependency on fossil fuels. However, even after decades of research the recalcitrance and complexity of LC residues, composed of polymeric cellulose, hemicellulose, and lignin, still pose a bottleneck for their economic utilisation. This problem can be possibly solved by the engineering of a robust microorganism that will degrade the LC polymers and directly co-valorise the spectrum of resulting sugars, aromatics, and organic acids. Such organism is not available.

Here, I propose a novel strategy that comprises of engineering inputs on the interior (metabolism), exterior (cell surface), and population levels of promising robust bacterial cell factory Pseudomonas putida KT2440 with a special potential to co-metabolise substrates derived from all three major LC components. This strategy will lead to the effective degradation of LC polymers and parallel co-conversion of obtained oligomers and monomers into acetyl-CoA and a final valuable product - recyclable and fully degradable polyhydroxyalkanoates (PHA) - by a single microbial host.

My team will re-shape P. putida’s carbohydrate metabolism for fast co-utilisation of (hemi)cellulosic sugars with lignin-born aromatics and their co-streaming into PHA. In parallel, we will enrich the surface of P. putida PHA producer with high numbers of designer lignocellulosomes – artificial enzymatic nanomachines for extracellular degradation of LC polymers. The required de-polymerising enzymes will be overproduced in developed autolytic P. putida strains with a unique synthetic genetic circuit securing continuous enzyme release. Autolytic strains will be combined with lignocellulosome-bearing PHA production strain in a synthetic bacterial consortium which will perform the challenging task sketched above and, once proven functional, enable sustainable production of biochemicals by P. putida.

Sustainable Development Goals

Masaryk University is committed to the UN Sustainable Development Goals, which aim to improve the conditions and quality of life on our planet by 2030.

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