Date

Monday 07 Apr 2025

Time

15:15 - 15:45

Location

BW020

Supervisor

Stephan Hacker

External supervisor

Lennart Schada von Borzyskowski

Jury

Remus Dame

Various environmental problems are caused by the accumulation of pollutants in nature. The accumulation of pollutants can be combated through bioremediation, the utilization of microbes to degrade pollutants. Recently, progress has been made in the degradation of the pollutant polyethylene terephthalate, one of the main polymers in plastic. The enzyme FAST-PETase shows great promise for plastic bioremediation since it converts PET into ethylene glycol (EG) and terephtalic acid (TPA) under moderate conditions. To ensure a good expression of FAST-PETase, it should be metabolically linked to endogenous metabolic pathways of microbes. The PET monomer, ethylene glycol is connected to cell growth through the β-hydroxyaspartate cycle (BHAC). Thus, host organisms should ideally contain the BHAC pathway. Examples of potential candidates for FAST-PETase expression are Ruegeria pomeroyi (R. pomeroyi) and Dinoroseobacter shibae (D. shibae). These members of the Roseobacter clade display versatile trophic strategies, high adaptability to diverse environments and a predisposition to horizontal gene transfer and homologous recombination. These characteristics make them ideal microbes for bioremediation. However, to utilize the Roseobacter bacteria new genetic tools are needed. In this study it was attempted to validate a new genetic tool through the complementation of the bhcC in a knockout strain of D. shibae. The vector was constructed succesfully but no modified D. shibae could be selected. Moreover, in this study the degradation of bis(2-hydroxyethyl) terephthalate (BHET) by R. pomeroyi was observed. R. pomeroyi was equiped with vectors containing the gene for FAST-PETase. During the experiment it was discovered that R. pomeroyi has endogenous MHETase activity. Moreover, when the expression was mediated by the promoter cinR from Rhizobium leguminosarum (R. leguminosarum) faster degradation was observed than when the vector contained the tuf1 promoter from Phaeobacter inhibens (P. inhibens).