Photosynthesis is the sole biological process to capture atmospheric CO₂. The overall objective of ‘ACCeSS’ is to optimize the CO₂ uptake and fixation of CO₂ by microorganisms, thereby converting the CO₂ into high-value carbon-based products. These products should facilitate the long-term storage of atmospheric CO₂ in an environmentally friendly manner, offering a solution of significant interest and benefit to humanity.   
One of these products are polysaccharides, such as chitin or cellulose. These polysaccharides are renewable, biocompatible, biodegradable, and non-toxic compounds that have biological properties such as: anti-cancer, antioxidant, anti-microbial and anti-coagulant properties. In addition, they are used as biomaterials in a wide range of applications: for biomedical purposes such as for artificial skin, bones, and cartilage regeneration, for food preservation and for pharmaceutical purposes like drug delivery.

The objective within the ACCeSS project 8 (AP8) project is to investigate pathways for synthesis and secretion of a broad spectrum of exopolysaccharides (EPS) of biofilm forming microorganism and to adapt these pathways to facilitate EPS secretion in photosynthetic active microorganisms. Following secretion of the polysaccharides, these can be harvested from the extracellular media.

In the AP8 we will focus on "synthase dependent EPS secretion" pathways. The advantage of these pathways is that they link polymer formation with transport above the membrane, obviating the need for input of metabolic energy in the form of ATP/GTP. Moreover, these pathways are regulated by cytosolic c-di-GMP, which could be employed for the implementation of an UV-switch for light-dependent EPS synthesis. The majority of synthase-dependent pathways are present in a wide range of forms, with varying numbers of proteins required for their functioning. These pathways have been identified in a range of bacterial species, including both gram-positive and gram-negative bacteria, as well as cyanobacteria and thermophiles from the Aquificales order. This allows for the selection of appropriate EPS systems from a range of donor cells with diverse characteristics, including the capacity for transport above one or two membranes, pH and temperature stability, as well as modifications and complexity.       

In the lab the bioengineering of the EPS pathways will be further supported by the ongoing structural and biochemical analysis of the secretion machinery, which will facilitate the tuning and optimization of the interactions.