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Prof. Vujcic's Laboratory for experimental biochemistry, enzymology and biotechnology focuses mainly on two groups of enzymes - hydrolases and oxidoreductases and their biotechnological applications. Main sources of these enzymes are fungi and bacteria (known producers as well as soil isolates) that secrete them naturally or they are genetically modified to produce recombinant enzymes. Since the enzymes from those two classes are mainly involved in the raw biomass utilization, for obtaining complete and sustainable biomass conversion processes we are orientated in enzyme production, purification, characterization and improvement. Innovative enzyme solutions can potentially improve efficient biomass utilization, and hence significantly contribute to the transition to a bio-based economy by offering environmentally friendly technologies for the production of biofuels, added value chemicals, and materials from biomass resources. The discovery and characterization of new enzymes and processes provides a foundation for the development of enzyme technology for the improved use of renewable biomass resources in the bioethanol, food and agricultural industries.
Breakthrough in our research on amylases is discovery of raw starch digesting amylase from Bacillus licheniformis (Bozic et al, 2011, Biochem Eng J), enzyme with remarkable stability and highly active on raw starch enabling new development in starch based bioethanol plants. Complexity of isoenzymes mixture produced by microbes requires sophisticated methods to be devoleped to identify enzyme form with highest contribution for desired process and hence development of zymographic techniques is another important aspect of our work (Dojnov and Vujcic, 2012, Anal. Biochem.; Bozic and Vujcic, 2005, Electrophoresis). Process development sometimes demands enzymes to operate under harsh conditions and stabilization is conventionally achieved via immobilization on inert support and/or chemical modification. We use array of commercially available carriers as well as newly synthesized carriers for enzyme immobilization (Milovanovic et al, 2007, Food Chem; Vujcic et al, 2010, J Agr Food Chem; Loncar and Vujcic, 2011, J Haz Mat). Interactions of small molecules (natural products or reactive aglycones released from glycosides upon reaction with glycosidase) with DNA is important aspect of investigating their biological activity and our group use spectrofluorimetric and electrophoretic methods to gain insight into this process.
Oxidoreducates comprise of large group of enzymes with vast array of reactions they catalyze. Our focus is on laccase and peroxidase catalyzed oxidation of phenols and dyes for wastewater treatment and their potential use for lignin degradation. Current research efforts are put into bacterial enzymes as promising replacement for fungal counterparts due to their thermostability and ease of genetic manipulation (Loncar et al, 2013, Biores Tech; Loncar et al, 2014, Int Biodet Biodegr). Protein engineering techniques are used for enzyme stabilization and tailoring for specific synthetic reactions.
Our research is funded by Ministry of Education and Science of Republic of Serbia, International Centre of Genetic Engineering and Biotechnology and via participation in COST actions. Laboratory is equipped with standard equipment for biochemistry (FPLC, protein electrophoresis and isoelectric focusing, spectrophotometer), molecular biology (PCR, electroporator, imager and DNA electrophoresis), fermentation technology (incubators, laboratory shakers, laboratory fermenter 2L) and with HPLC with diode array detector for analysis of reaction products. We have active collaborations with Prof. Dr Josep López Santin from Autonomous University of Barcelona (Barcelona, Spain), Prof. Dr Marco W. Fraaije, University of Groningen (Groningen, Netherlands).