Bench scale production of xanthan from date extract by Xanthomonas campestris in submerged fermentation using central composite design

Abstract

In this research, xanthan production from date extract was done by using bacterium Xanthomonas campestris PTCC1473 in submerged fermentation (SmF). The impact of different initial concentrations of carbon (date extract) and nitrogen (NH₄NO₃) sources on cell growth and xanthan production was evaluated. Inoculum (72 h) from the YMB medium was added to the substrate with defined chemical components (nitrogen, sugar, moisture, ash and pH) and incubated. Central composite design (CCD) was used to evaluate the effects of carbon and nitrogen sources on production yield. The results indicate a decrease of cell growth in carbon source concentration up to 50 g/l. The highest cell growth and xanthan production were achieved at 40 g/l concentration of carbon source. The nitrogen source concentration did not cause a significant effect on cell growth; but the highest concentration of xanthan was produced in 0.2 g/l of nitrogen source. The ratio of carbon to nitrogen content had a significant impact on xanthan production. In the optimum condition, maximum concentration of produced xanthan yield and productivity was seen at 11.2 g/l and 8.19 g/kg.day, respectively.

Key words: Xanthan, submerged fermentation, date extract, Xanthomonas campestris, central composite design.