Bioconversion of hemicellulosic sugars into xanthan gum by isolated Xanthomonas campestris strain

BACKGROUND AND OBJECTIVESXanthan gum, a widely utilized food additive known for its thickening, stabilizing, and emulsifying properties, is traditionally produced through fermentation using Xanthomonas campestris bacteria on glucose or sucrose-based media. However, there is increasing interest in investigating alternative feedstocks to enhance sustainability and reduce costs. This study examines the potential of isolated Xanthomonas campestris strains to convert hemicellulosic sugars from biomass into xanthan gum.MATERIALS AND METHODSXanthomonas sp. was isolated from walnut green shell samples in Marand City. Phenotypic tests were conducted on the isolates, including gram staining, biochemical reactions, and physiological assessments. Molecular identification involved DNA extraction using the phenol/chloroform method and confirmation through PCR amplification of the ۱۶S rRNA gene. The resulting PCR products were sequenced and analyzed using the BLAST program in the NCBI database for specie identification. To prepare hydrolysate containing hemicellulosic sugars, sorghum stem (۱۰% w/v) was stirred in acetone/water solution (۵۰%) with ۰.۱% sulfuric acid. The mixture was pretreated at temperatures ۱۲۰, ۱۵۰, and ۱۸۰ °C for ۳۰ or ۶۰ minutes. The liquid phase was used to produce hemicellulose xanthan gum.RESULTS AND DISCUSSIONThis study investigated the production of hemicellulosic xanthan gum from sorghum stalk hydrolysate using organosolv pretreatment. The impact of temperature and duration on xanthan gum yield was examined, revealing a negative relationship between pretreatment intensity and yield. However, a maximum yield of approximately ۱۲.۷۸ g/L was achieved. Characterization studies indicated that the hemicellulosic xanthan gum had lower viscosity than standard xanthan gum. This approach enables the direct production of xanthan gum with reduced viscosity suitable for edible applications.CONCLUSIONTo the best of our knowledge, this is the first report on the bioconversion of hemicellulose sugars into xanthan gum, offering valuable insights for future research and industrial applications.

کلیدواژه ها:

Xanthan gum ، Hemicellulose ، Xanthomonas campestris ، Sorghum ، Organosolv treatment.