| Abstract [eng] |
One of the world's most sustainable solutions is to switch from polymers made from fossil fuels to biopolymers. One of these is xanthan. This biopolymer can be applied in many industries, medicine, pharmaceuticals, food and other fields due to its unique rheological properties, non-toxicity and excellent compatibility with the human body. By optimizing the industrial production of xanthan, the replacement of polymers obtained by chemical synthesis with xanthan can be achieved in the future. The aim of this study was to evaluate the influence of various fermentation factors on xanthan synthesis, product yield and properties. The effect of ten carbon nutrient sources and three nitrogen nutrient sources on bacterial growth, xanthan concentracion and properties was determined by study with Xanthomonas campestris bacteria. The influence of the initial carbon source concentration on the synthesis process was evaluated and also the optimal fermentation time was determined. The properties of synthesized xanthan samples were investigated as solubility in different solvents, the evaluation of structure by the FTIR method, evaluation of antioxidant properties by Fe (III) reduction, FRAP and DPPH methods. The results obtained in the study showed that the best alternative source of carbon for glucose was stevia, and the alternative source of nitrogen for peptone is potassium nitrate. Using these nutrient sources for xanthan synthesis, a concentration of 182.88 g/l xanthan was obtained after 24 hours of fermentation. Taking into account the different fermentation times, it was decided that the optimal duration was 24 hours, as longer fermentation does not give significantly better results. The optimal initial concentration of carbon in the nutrient medium was found to be 20 g/l. During the determination of antioxidant properties, it was observed that the application of different tests for the determination of reducing properties gives different results due to the method of determination of these properties in the test and different operating media. Vibration absorption bands for xanthan - specific groups can be seen from resulting FTIR structure determination: O-H, C-H, C=O, C-O-C and others groups. Based on the obtained results, a recommended industrial scheme for xanthan synthesis was developed. |
