A Novel Sphingan Containing Enriched Guluronic Acid Residues and Its Hydrogel Properties

Area of Science:

• Microbiology
• Biochemistry
• Polymer Science

Background:

• Sphingans are microbial polysaccharides with diverse industrial applications.
• Conventional sphingans often have limitations in specific functional properties.
• Novel biopolymers are sought for advanced hydrogel applications.

Purpose of the Study:

• To characterize a novel sphingan, HL gum, produced by Sphingomonas sp. HL-1.
• To investigate the chemical composition and physical properties of HL gum.
• To evaluate the potential of HL gum in hydrogel formation.

Main Methods:

• Fermentation of Sphingomonas sp. HL-1 using mixed sugars.
• Characterization of HL gum's molecular weight, chemical composition (HPLC, NMR).
• Rheological analysis and gelation studies at varying temperatures and salinities.
• Scanning Electron Microscopy (SEM) for morphological analysis.

Main Results:

• High yield (28.7 g/L) of HL gum with high molecular weight (2.03 × 10^6 Da).
• Unique composition: enriched in guluronic and galacturonic acids, low rhamnose.
• Demonstrated shear-thinning behavior, heat-activated gelation (1% w/v at 90°C), and high gel strength (2950 ± 130 g/cm^2).
• Stable gel formation under high salinity (50 g/L).
• SEM revealed temperature-dependent morphological transitions consistent with sol-gel behavior.

Conclusions:

• HL gum is a novel sphingan with a unique chemical structure and superior gelation properties.
• Its ability to utilize mixed sugars efficiently and form robust hydrogels makes it a promising candidate for food, biomedical, and industrial applications.
• HL gum offers advantages over conventional sphingans due to its specific composition and functional characteristics.