Xanthan gum biosynthesis using Xanthomonas isolates from waste bread: Process optimization and fermentation kinetics

• Published in: Food science & technology Vol. 101; pp. 40 - 47
• Main Authors: Demirci, Ahmet Sukru, Palabiyik, Ibrahim, Apaydın, Demet, Mirik, Mustafa, Gumus, Tuncay
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2019
• Subjects: Response surface methodology; Waste bread; Xanthan gum; Xanthomonas isolates; Xanthan gum; Response surface methodology; Xanthomonas isolates; Waste bread
• ISSN: 0023-6438; 1096-1127
• DOI: 10.1016/j.lwt.2018.11.018

Waste bread hydrolysate was used as a biosource for xanthan production by various isolates and standard bacteria (Xanthomonas campestris DSM 19000). Influence of operational conditions used in the process of xanthan production were evaluated through yield of xanthan, rheological properties of aqueous solution and fermentation kinetics. For the highest yield and viscosity, optimum conditions including carbon source concentration, inoculum volume and agitation rate were determined for 4 different strains by using response surface methodology. The highest gum yield as 14.3 g/L was obtained by Xanthomonas axonopodis vesicatoria and the highest conversion rate of waste bread to xanthan gum was found as %14.1 for Xanthomonas hortorum pv. pelargonii. Whereas, the highest aqueous solution viscosity of gum produced from standard bacteria was 11.2 Pa.sn at glucose ratio of 4%, inoculum volume of 5% and mixing rate of 225 rpm. For fermentation kinetics; the values of growth associated parameters revealed that they are mostly affected by the rate of xanthan gum production and substrate consumption. In general, optimum conditions to obtain the highest xanthan gum yield were different from that to achieve the highest viscosity. This study shows the potential of waste bread hydrolyzates as the promising economic carbon source for xanthan gum production. [Display omitted] •Highest xanthan gum yield (14.3 g/L) was obtained by X. axonopodis vesicatoria from waste bread.•14.1 g of xanthan gum can be obtained from 100 g waste bread.•X. campestris DSM 19000 produced gum with the highest viscosity.•Cell growth of microorganisms depended on xanthan gum production and substrate consumption.