Screening of Local Wild Xanthomonas Species for Xanthan Production on Crude Glycerol-based Medium

In this study, the effect of cultivation time on xanthan biosynthesis by different Xanthomonas campestris and Xanthomonas euvesicatoria strains, isolated from crucifers and pepper leaves, respectively, was examined. Xanthan was produced by submerged cultivation on crude glycerol-based medium at a laboratory level under aerobic conditions at 30 °C and 150 rpm for 168 h and 240 h. Bioprocess efficacy was estimated based on the xanthan concentration in media at the end of bioprocess and its average molecular weight. According to the obtained results, Xanthomonas strains have statistically significant effect on xanthan concentration in cultivation media when biosynthesis is performed by X. euvesicatoria strains, and cultivation time has significant effect on this parameter only when bioprocess is performed by X.campestris strains. The combination of Xanthomonas strains and cultivation time has a statistically significant effect on xanthan concentration in medium for both groups of isolates. The obtained results show that all applied Xanthomonas strains and cultivation time as well as their combination have statistically significant effect on average molecular weight of xanthan produced in applied experimental conditions. It is found that X. euvesicatoria strains produce higher amount of xanthan in a shorter period of time (168 h) when compared to the X.campestris strains. Xanthan of higher average molecular weight was produced when cultivation of both groups of isolates was performed for 240 h in applied experimental conditions. Results obtained in this research suggest that X. euvesicatoria strains have the greatest potential for application in biotechnological production of xanthan on crude glycerol-based medium.