The three FUTURE project Objectives and the progress achieved during the two-year period are as follows:
[1] Optimisation of glucose metabolism in available P. putida chassis:
During the first part of the FUTURE project, the Experienced Reseracher (ER) focused on solving the problem of non-optimal glucose utilisation by P. putida. The energetics of sugar assimilation was improved and the glycolytic flux streamlined by teaching P. putida how to utilise cellobiose (dimer of glucose, the shortest cellooligosaccharide) instead of glucose. Enzyme from cellulolytic bacterium Thermobifida fusca allowed P. putida to grow rapidly on cellobiose and use it as as a sole carbon source. The outcomes of the first project part were published in a renowned journal (Dvořák et de Lorenzo, Metab Eng. 2018 Jul;48:94-108.) and used in a patent application.
[2] Engineering surface display and excretion of designer cellulosome components in P. putida chassis:
In the second part of the project, so called scaffoldin with protein domains cohesins that can bind corresponding dockerins at cellulolytic enzymes had to be displayed on the cell surface. ER developed rapid screening system, based on dockerin-tagged beta-glucosidase and fluorescent protein, for scaffoldin display monitoring and quantification in P. putida cells. Scaffoldins containing one or two cohesins were prepared by genetic engineering and exposed on P. putida surface with very good efficiency using the display system borrowed from bacterium Escherichia coli. Dockerin-tagged cellulases, selected based on their compatibility with P. putida host, are currently being combined with cohesin displaying cells to allow degradation of cellulosic substrates to glucose. A publication summarizing the aforementioned results is in preparation.
[3] Probing PHA biosynthesis from cellulosic waste in re-factored P. putida:
Synthesis of PHA biopolymer in P. putida was previously demonstrated from fatty acids and unrelated substrates such as glucose, but never from cellooligosaccharides. Within the scope of project FUTURE, ER showed for the first time, that PHA can be produced in engineered P. putida also from biotechnologically relevant cellobiose which forms significant part of cellulosic hydrolysates. The data are included in publication in preparation.
To conclude, metabolism of P. putida was successfully engineered toward more efficient sugar utilisation. Synthetic scaffoldin with two cohesins was successfully displayed on P. putida surface and is being used for attachment of cellulases. The project has already given rise to two highly impacted publications (IF 10 and 8) and one patent application. Two more publications are in preparation. Project concept and results were presented at four renowned international scientific conferences, two student/postdoc scientific meetings, EMBO training course, one seminar for public, two university lectures, and one newspaper interview. Project was also discussed with numerous individuals visiting Receiving Laboratory, including some of the most influential personalities in the fields of synthetic biology and metabolic engineering. News on the project and its outcomes were regularly spread through the social media (Facebook, Twitter). We estimate that the project reached thousands of persons from academia, industry, and general public.
