Production of welan gum from cane molasses by Sphingomonas sp. FM01

Abstract

As an extracellular exopolysaccharide, welan gum could serve as a suspending agent, stabilizer, emulsifier and thickener with characteristics that include bio-adhesion, non-toxicity, biocompatibility and biodegradability. In this study, Sphingomonas sp. FM01 was applied to effectively produce welan gum using cane molasses as the carbon source. After pretreatment with phosphoric acid and polyacrylamide, 60 g/L cane molasses combined with 6.0 g/L beef extract, 3 g/L KH₂PO₄, 0.5 g/L MgSO₄, 15 mmol/L H₂O₂ and 4 mg/L niacin significantly improved the fermentation performance of Sphingomonas sp. FM01, increasing the production of welan gum to 37.65 g/L. Investigation of the rheological behavior of the welan gum obtained from the molasses-welan gum mixture showed it had an acceptable molecular weight and similar rheological properties and better viscosity stability compared to that obtained from sucrose, indicating that cane molasses could be explored as a suitable and inexpensive substrate for cost-effective welan gum production.

Keywords: Cane molasses; Pretreatment; Rheological behavior; Sphingomonas; Welan gum.