Isolation and characterization of an exopolymer produced by Bacillus licheniformis: In vitro antiviral activity against enveloped viruses

[Display omitted] •B. licheniformis produced an EPSp composed of polyglutamic acid and teichoic acid.•The negative charge content of the EPSp increased its electrostatic properties.•The EPSp was efficient at inhibiting viral entry against enveloped viruses.•The EPSp could have potential applications as a prophylactic therapeutic biomolecule. The exopolymer (EPSp) produced by the strain B. licheniformis IDN-EC was isolated and characterized using different techniques (MALDI-TOF, NMR, ATR-FTIR, TGA, DSC, SEM). The results showed that the low molecular weight EPSp contained a long polyglutamic acid and an extracellular teichoic acid polysaccharide. The latter was composed of poly(glycerol phosphate) and was substituted at the 2-position of the glycerol residues with a αGal and αGlcNH2. The αGal O-6 position was also found to be substituted by a phosphate group. The antiviral capability of this EPSp was also tested on both enveloped (herpesviruses HSV, PRV and vesicular stomatitis VSV) and non-enveloped (MVM) viruses. The EPSp was efficient at inhibiting viral entry for the herpesviruses and VSV but was not effective against non-enveloped viruses. The in vivo assay of the EPSp in mice showed no signs of toxicity which could allow for its application in the healthcare sector.