PhD Position in Chemistry and Biotechnology (# of pos: 2)

Updated: about 1 year ago
Deadline: 21 Jun 2019

We offer 4-year PhD position in Characterization of Soil Bacterial Enzymes for the use in the Process of Lignin Valorization and Biomass Conversion.
Supervisor: Dr. Tiit Lukk

Lignin is the second most abundant biopolymer on earth. While lignin provides biomass with structural rigidity, due to its  chemically recalcitrant nature, it also offers plant a layer of protection against a number of natural processes that would lead  to its degradation. The majority of plant biomass consist of cellulose, a polymer of β-1,4-conjugated D-glucose molecules (40-60% dry weight) but lignin content and structure in lignocellulose are highly variable, and differ from  species to species in its composition and in the dry mass range (15 - 30%). Due to the global trend of moving away from fossil fuels and towards renewable energy sources, lignocellulose has gained much attention as a renewable resource for  the production of liquid fuels (bioethanol, biodiesel) but also as a resource from which to derive alternatives to petrochemicals (lignin).
When considering natural degraders of plant biomass, three groups of organisms are typically discussed: white rot fungi, brown rot fungi and certain groups of soil bacteria. Albeit white rot fungi are effective in completely mineralizing lignin to CO2, brown rot fungi and soildwelling actinobacteria do so at slower speed and effectiveness. However, from the standpoint  of industrial biochemistry, actinobacterial enzymes that are involved in lignin deconstruction (listed below)  are of particular interest due to much wider pH activity range and enhanced tolerance to elevated temperatures when  compared to their fungal counterparts.

What we offer
Lignin biochemistry laboratory at TalTech offers two positions for prospective PhD students to study the biochemistry and structural biology of lignin degrading enzymes from several actinobacterial strains, some of which are thermophilic  organisms. The laboratory is involved in two industrial collaborations. One of these is working toward deriving novel chemicals from woody biomass such as wood bark, that would otherwise be burned for thermal energy, thus  increasing the value of this commodity. Literature suggests that lignin, that has been extracted in the various processes in the paper pulping industry can be valorized from a mere 50 €/t with enzymatic processes to greater than 1500 €/t, adding some 30-fold value to the staring material.

The doctoral work will focus on one or multiple of the following classes of enzymes:

  • laccases and laccase like copper oxidases,
  • dye-decolorizing peroxidases (DyP) and
  • aryl alcohol oxidases.

The PhD student will gain extensive experience in molecular cloning, mutagenesis, protein purification, enzyme kinetics, protein crystallography as well as multiple analytical tools required for the analysis of lignin and its degradation products. The lignin biochemistry laboratory at TalTech conducts interdisciplinary research, which sets up the graduate student for a successful career in industry or academia post-graduation.

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