The use of natural polysaccharides as biomaterials is gaining importance in tissue engineering due to their inherent biocompatibility. In this direction, the present study aims to explore the structure and biocompatibility of the EPS produced by Virgibacillus dokdonensis VITP14. This marine bacterium produces 17.3 g/L of EPS at 96 h of fermentation. The EPS was purified using ion exchange and gel permeation chromatographic methods. The porous web-like structure and elemental composition (C, O, Na, Mg, P, S) of the EPS were inferred from SEM and EDX analysis. AFM analysis revealed spike-like lumps with a surface roughness of 84.85 nm. The zeta potential value of -10 mV indicates the anionic nature of the EPS. Initial molecular characterization showed that the EPS is a heteropolysaccharide composed of glucose (25.8%), ribose (18.6%), fructose (31.5%), and xylose (24%), which are the monosaccharide units in the HPLC analysis. The FTIR spectrum indicates the presence of functional groups/bonds typical of EPSs (O-H, C-H, C-O-H, C-O, S=O, and P=O). The polymer has an average molecular weight of 555 kDa. Further, NMR analysis revealed the monomer composition, the existence of two α- and six β-glycosidic linkages, and the branched repeating unit as →1)[α-D-Xylp-(1→2)-α-D-Glcp-(1→6)-β-D-Glcp-(1→5)]-β-D-Frup-(2→2)[β-D-Xylp-(1→4)]-β-D-Xylp-(1→6)-β-D-Fruf-(2→4)-β-D-Ribp-(1→. The EPS is thermally stable till 251.4 °C. X-ray diffraction analysis confirmed the semicrystalline (54.2%) nature of the EPS. Further, the EPS exhibits significant water solubility (76.5%), water-holding capacity (266.8%), emulsifying index (66.8%), hemocompatibility (erythrocyte protection > 87%), and cytocompatibility (cell viability > 80% on RAW264.7 and keratinocyte HaCaT cells) at higher concentrations and prolongs coagulation time in APTT and PT tests. Our research unveils the significant biocompatibility of VITP14 EPS for synthesizing a variety of biomaterials.

exopolysaccharides, fermentation, Marine bacteria, anticoagulant activity, Structural characterization, halophiles, biomaterial, cytocompatibility, hemocompatibility

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
4,6,2,5,6,2	aDXylp
4,6,2,5,6	aDGlcp
4,6,2,5	bDGlcp
4,6,2	bDFrup	61.02	98.04	68.52	69.20	75.15	61.50
4,6,4	bDXylp
4,6	bDXylp
4	bDFruf	62.40	101.61	70.59	69.45	81.03	63.05
	bDRibp


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
4,6,2,5,6,2	aDXylp
4,6,2,5,6	aDGlcp
4,6,2,5	bDGlcp
4,6,2	bDFrup	3.48-3.61	-	3.79	3.85	3.88	3.51-3.58
4,6,4	bDXylp
4,6	bDXylp
4	bDFruf	3.59-3.71	-	3.97	3.86	3.76	3.64-3.77
	bDRibp


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
4,6,2,5,6,2	aDXylp
4,6,2,5,6	aDGlcp
4,6,2,5	bDGlcp
4,6,2	bDFrup	61.02/3.48-3.61		68.52/3.79	69.20/3.85	75.15/3.88	61.50/3.51-3.58
4,6,4	bDXylp
4,6	bDXylp
4	bDFruf	62.40/3.59-3.71		70.59/3.97	69.45/3.86	81.03/3.76	63.05/3.64-3.77
	bDRibp

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

[*]OC[C@@]1(O[C@H]2[C@H](OC[C@H]3O[C@@](CO)(O[C@@H]4CO[C@@H]([*])[C@H](O)[C@@H]4O)[C@@H](O)[C@@H]3O)OC[C@@H](O[C@@H]3OC[C@@H](O)[C@H](O)[C@H]3O)[C@@H]2O)OC[C@@H](O[C@@H]2O[C@H](CO[C@H]3O[C@H](CO)[C@@H](O)[C@H](O)[C@H]3O[C@H]3OC[C@@H](O)[C@H](O)[C@H]3O)[C@@H](O)[C@H](O)[C@H]2O)[C@@H](O)[C@@H]1O

1177.024 g/mol (C₄₄H₇₂R₂O₃₆, R = next and previous repeats, not counted in mol weight)