: properties of xanthane have made it so much useful in various industries including food medicine and hygienic, oil, ceramics, printing, etc and the annual consumption throughout the world is ever increasing. as a result, it is tried to reduce production costs for the better xanthan gum production rates by means of available cheaper substrates as well as the application of different operation methods. The aim in this work was to examine the possibility of xanthan production from grape extract sugar source for the first time and relevant production volume from other carbon sources such as date extract, and compare its results with that. For this purpose, three influential parameters namely carbon (grape extract and date extract), phosphorus (K 2 HPO 4 ), and nitrogen (NH 4 NO 3 ) were considered within the respective ranges of 30-150, 4-12, and 3-9 g/L. designed of experiments was performed using central composite design method in three levels and twice repetition in an absolute random way under constant temperature (28° C) and 72 hours fermentation. In this project, dry weight method was applied to measure the cellular mass and yielded product. The influence of different parameters on production rate was examined and xanthan gum production and cellular mass model was gained for both carbon sources i.e. grape extract and date extract. Optimum levels and the amount of produced xanthan were determined by the software in these levels. After that, experimental tests were taken in these levels. The largest amounts of theoretical and experimental production of xanthan from grape extract sugar source at 86.97 g/L carbon source, 8.2 g/L phosphorus source, and 3 g/L nitrogen source were respectively equal to 10.30 and 10.16 g/L, and the same for date extract sugar source in levels of 77.3 g/L carbon source, 12 g/L phosphorus source, and 3 g/L nitrogen source were respectively equal to 13.27 and 12.74 g/L. Taking into account the fact that this process is divided into two phases i.e. microbial growth at the first 24 hours of fermentation process fllowed by production in the second phase. Optimum temperature as well as optimum carbon source are different in these two phases, therefore, another experiment was designed in order to evaluate the effect of variation during microbial growth and xanthan product. During the first 24 hours of fermentation, experiments were started at 28° C and 30g/L concentration of carbon source and optimum levels of phosphorus and nitrogen sources, while temperature of production phase was increased to 32° C and 30 g/L carbon source was added to the fermentation Erlenmeyer under sterile conditions. the result of these tests, for both grape and date extracts sugar sources, respectively 16.7 and 15.6% increase were gained in the production rate in comparison with the tests under constant temperature without feeding in optimum levels.
