Production, characterisation, and application of exopolysaccharide extracted from a glacier bacterium Mucilaginibacter sp. ERMR7:07

Abstract

Mucilaginibacter sp. is known as an exopolysaccharide (EPS) producer. In this study, a potentially novel species of genus Mucilaginibacter was used to extract EPS. Statistical optimisation by Response surface methodology produced 26.4 mg/mL EPS at 20℃, pH 7.4 using 47 mg carbon source/mL. The molecular weight of the extracted EPS was 3045.09 Da as determined by MADI-TOF/TOF-MS. Structural characterisation by monosaccharide composition, methylation, Fourier-transform infrared spectroscopy, and Nuclear magnetic resonance analysis revealed that the EPS was a linear polysaccharide with the sugar backbone of α-D-Glciv(1→4)α-D-Glciii(1→3)β-D-Glcii(1→6)α-D-Glci. The extracted EPS provided 97.91 % viability to mesophilic Escherichia coli under freezing conditions (-80℃) for up to 7 days. Additionally, extracted EPS showed metal ion biosorption ability for Cu2+ (8.36 mg/g), Fe2+ (4.47 mg/g), Mn2+ (0.12 mg/g), and Zn2+ (0.103 mg/g). Owing to these properties, the extracted EPS can be explored for its application as a cryoprotective agent and as a medium to remove toxic metal ions. To the best of our knowledge, this is the first report on the extraction and characterisation of EPS from the genus Mucilaginibacter.