Biotechnological Valorization of Crude Glycerol from Biodiesel Industry: Xanthan Production in Lab-scale Bioreactor by Xanthomonas euvesicatoria

Abstract

In this study, xanthan production by local wild-type Xanthomonas euvesicatoria PL4 strain in a 3 L stirred tank bioreactor from a medium containing crude glycerol generated in biodiesel industry was examined, and properties of separated biopolymer were determined. Xanthan was biosynthesized by submerged batch cultivation of producing microorganism in a medium with glycerol content of 20 g/L. The bioprocess was monitored by analysis of cultivation medium at predetermined time intervals, and its success was estimated based on the xanthan concentration in the medium, degree of initial glycerol conversion into xanthan, degree of metabolized glycerol conversion into xanthan, degree of glycerol conversion, degree of total nitrogen conversion, and degree of total phosphorus conversion. Xanthan in concentration of 13.31 g/L was biosynthesized under the applied experimental conditions, and total glycerol, nitrogen, and phosphorous conversions of 76.23%, 64.70%, and 40.63% were achieved, respectively. The results obtained in this study suggest that the applied strain has the ability to produce xanthan with excellent properties on a crude glycerol-based medium. The findings of this study can contribute to future investigations which will aim to improve the production of xanthan on crude glycerol-based medium and find new possibilities for its application.