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Research Group 4 - RG4 - Zoran Vujčić


Research description:

There is a global interest of enzyme implementation in all sorts of industrial processes such as the processes that are focus of our research; food biotechnology, biofuels and preservation of environment. Our research topics are directed toward study and optimization of the conditions for production and purification of enzymes from plant, animals and microorganisms and their application as pure or in complex enzyme cocktails (CEC), soluble or immobilized, in food biotechnology, pure and cheap bioethanol production and environmental protection.
There is an ongoing world interest in obtaining multienzymes preparations i.e. simultaneous excretion of hydrolytic enzymes such as peptidases, amylases, glucanase, phytases and xylanases when microorganisms are grown on the complexed media composed of diverse substrates. By zymogram techniques and with the use of substrates of interest desired enzymes capable of hydrolysis of raw starch, insoluble proteins, cellulose, glucan, xylose and other substrates can be detected. In this way, complexed enzyme cocktails are obtained as well as procedure for improvement of food quality that can be implemented in areas with the lack of high technologies.
Scaling-up the production of enzymes from laboratory to industry is strategic orientation of great number of countries. Therefore, selection of microorganisms and its genetic manipulations enables obtainment of enzyme source in quantities comparable with plant and animal sources. Wild type and recombinant enzymes are further purified to homogeneity by chromatographic and electrophoretic techniques and characterized in details by biochemical and biophysical methods. According to the results obtained, further improvement of enzyme properties is conducted.
By the conventional processes for food proteins or biofuel production large amount of waste materials, representing environmental pollution treats are obtained. One of the aims of our research is to make a connection between those processes using CEC and in that way to facilitate both, obtaining of food protein as well as remains after fermentation. Using grains and degreased soy and sunflower cultivars as a source of proteins, condition for the proper extraction of proteins, such as type and dose of the enzyme to be added, pH, temperature, ionic strength, and addition of detergents or organic solvents will be examined. All of these parameters in addition to sequential enzyme treatment examination will be studied in order to transform as much as water insoluble components into soluble once as possible. By the implementation of green chemistry, costs of the cold raw starch hydrolysis for bioethanol production will be decreased; extraction of insoluble proteins will be facilitated while quantity of waste materials will be considerably lowered. In this way obtained bioethanol will hence lower expenses of production of more biological valuable food.
Insoluble, nonfermentable materials that remain after sequential extraction in combination with other plant waste materials and mineral materials will be used as growth media for plant and fungi. After harvesting of obtained plant and fungi biomass remained will be used as source material for enzyme extraction or as organic fertilizer thus making the use of grains as a resource for obtaining the food of higher overall value completely exploited. Fungi and waste protein solutions obtained from food industry will be used for purification of enzymes capable for detoxification of contaminated water, alone or in combination with physico-chemical processes. Generally, use of enzyme for removal of xenobiotics from waste waters does not generate the products that are more toxic than starting product as it can be the case when chemicals, ozonization or UV treatment are applied for same purpose. With the use of collection materials those newly obtained polymers will be adsorbed prior to attachment to the enzyme which will prolonged the half-life of enzyme. Significance of research will be pointed out through the examination of toxicity of free radicals and how they are influenced by antioxidants at molecular level i.e. on DNA and proteins.
Special research focuses are to obtain new supports (synthetic, modified natural or composed) and to examine supports, condition and procedures for immobilization of target enzymes. Stabilization of enzymes, as well as other food proteins through the chemical modification and consequently its effect on allergenicity will also be explored.


Research skills and methods applied by the group:
Group members and ongoing projects:

dr Nataša Božić, senior researcher, ICTM
Projects: Production and improvement of microbial and plant enzymes and microorganisms used for food processing, bioethanol production and environmental protection. Amylases from plants and Bacillus sp: cloning, expression, production, purification, characterization, immobilization, application. Peptidases from Morimus funereus: model system for food protein digestion and for nutritive and antinutritive effects of food components.

dr Miroslava Vujčić, part-time senior researcher, ICTM
Projects: Glucosidase from almond: purification, characterization, immobilization, application. DNA modifications and toxicity assay.

Biljana Dojnov, PhD student
Projects: Amylases from Aspergillus niger: production, purification, characterization, immobilization, application. Amylases from Morimus funereus and Cerambyx cerdo: model system for food carbohydrate digestion. Biethanol production with immobilized yeasts.

Aleksandra Milovanović, PhD student
Projects: Invertase from Saccharomyces cerevisiae: purification, characterization, modification, immobilization, application.

dr Uroš Anđelković, research assistant
Project: Purification, biochemical and biophysical characterization, stabilization and potential biotechnological application of new molecular forms of the external invertase from yeast Saccharomyces cerevisiae. Influence of differences in carbohydrate component on to stability and activity of glycoproteins.

Nikola Lončar, PhD student
Projects: Phenol-oxidases, peroxidases, galactosidases: cloning, expression, purification, characterization, immobilization, application. Influence of chemical modifications of food proteins on protein structure, function and allergenicity.

Irena Novaković, part-time PhD student
Projects: Polymer synthesis for enzyme immobilization. In vivo toxity assayes.

Marica Grujić, part-time PhD student
Projects: Cellulases from Aspergillus niger, Trichoderma sp. and Chaetomium globosum: production, purification, characterization, immobilization, application.

Ratko Pavlović, MS student
Projects: Cellulases from Morimus funereus and Cerambyx cerdo: model system for food celullose fiber digestion.


Collaborations
Selected recent publications:
  1. Lončar N, Božić N, Anđelković I, Milovanović A, Dojnov B, Vujčić M, Roglić G & Vujčić Z. Removal of aqueous phenol and phenol derivatives by immobilized potato polyphenol oxidase. Journal of the Serbian Chemical Society, in press.
  2. Lončar N & Vujčić Z, Božić N, Ivanović J & Nenadović V (2010) Purification and properties of trypsin-like enzyme from the midgut of Morimus funereus (Coleoptera, Cerambycidae) larvae. Archives of Insect Biochemistry and Physiology 74(4), 232-246.
  3. Dojnov B, Lončar N, Božić N, Nenadović V, Ivanović J & Vujčić Z (2010) Comparison of a-amylase isoforms from the midgut of Cerambyx cerdo L. (Coleoptera: Cerambycidae) larvae developed in the wild and on an artificial diet. Archives of Biological Sciences 62(3), 575-584.
  4. Vujčić Z, Lončar N, Dojnov B, Milovanović A, Vujčić M & Božić N (2010) Characterisation of leucyl aminopeptidase from Solanum tuberosum tuber. Food Chemistry 121, 418-423.
  5. Andjelković U, Pićurić S & Vujčić Z (2010) Purification and characterisation of Saccharomyces cerevisiae external invertase isoforms. Food Chemistry 120(3), 799-804.
  6. Lončar N, Božić N, Nenadović V, Ivanović J & Vujčić Z (2009) Characterization of trypsin like enzymes from the midgut of Morimus funereus (Coleoptera: Cerambycidae) larvae. Archives of Biological Sciences 61(4), 713-718.
This web page is supported by Faculty of Chemistry, University of Belgrade