HotSolute

HOT Solute

ERA-CoBiotech Project

Thermophilic bacterial and archaeal chassis for extremolyte production

This ERA-CoBiotech project is developing thermophilic in vitro enzyme cascades as well as two new chassis, the thermophilic bacterium Thermus thermophilus (Tth, 65-75°C, pH 7.0) and the thermoacidophilic archaeon Sulfolobus acidocaldarius (Saci, 75-80°C, pH 2-4), as new thermophilic, bacterial and archaeal platforms for the in vivo production of novel high added-value products. These include ‘extremolytes’ that are small molecular compatible solutes found naturally in the cells of thermophilic species that accumulate in the cell in response to multiple environmental stresses and stabilize cellular components (including proteins, membranes). These Extermolytes possess great potential for application in the food, health care consumer care and cosmetics market. However, extremolytes cannot be produced in current mesophilic production hosts and therefore two thermophilic host Thermus thermophilus and Sulfolobus acidocaldarius of bacterial and archaeal origin, respectively, will be established as novel platform organisms.

The development of the newly designed ‘cell factories’ will be used for the production of three extremolytes, cyclic 2,3 di-phosphoglycerate (cDPG), di-myo-1,1’-inositol-phosphate (DIP) and mannosylglycerate (MG). These extremolyte biosynthetic pathways have been identified and many of the enzymes involved have been characterized. Within the project in addition to these enzymes, new candidates will be provided by (meta)genome searches and newly isolated strains from (hyper)thermophilic habitats.

Symbolic representation of the project workflow for the extremolyte production

Compatible Solutes and Extremolytes

Compatible solutes are ubiquitous and are found in all three domains of life. They accumulate to high concentrations in cells in response to diverse environmental stresses (e.g.heat, cold, osmotic stress, and desiccation) without interfering with cellular metabolism and allow their hosts to survive harsh environmental conditions by stabilizing and protecting biomolecular structures and the cellular conformation. Compatible solutes can be either taken up from the environment by the cell or are formed via de-novo synthesis. Many different compatible solutes are known that can be subdivided into different chemical categories such as (i) amino acids (e.g. α-glutamate, β-glutamate) and amino acid derivatives (e.g. glycine-betaine, ectoine, hydroxyectoine) as well as (ii) sugars (e.g. trehalose, MG), polyols (e.g. glycerol) and derivatives (51). Because of their protective effect on biological structures such as enzymes, DNA, membranes and whole cells, the compatible solutes have found commercial applications in different industrial fields such as food, health and consumer care and cosmetics.

Extremolytes are compatible solutes that are exclusively found in extremophiles and especially (hyper)thermophiles but not in mesophilic organisms. Such extremolytes include cyclic 2,3-di-phosphoglycerate (cDPG), di-myo-1,1’-inositol-phosphate (DIP) and mannosylglycerate (MG). However, their potential for industrial/biotechnological applications remains largely unexploited, mainly because efficient synthesis pathways to make their production economically viable are missing..

cyclic 2,3-di-phosphoglycerate

di-myo-1,1’-inositol-phosphate

mannosylglycerate