Isolation and physico-chemical characterisation of extracellular polymeric substances produced by the marine bacterium <i>Vibrio parahaemolyticus</i>

<div><p>A marine bacterial strain identified as <i>Vibrio parahaemolyticus</i> by 16S rRNA gene (HM355955) sequencing and gas chromatography (GC) coupled with MIDI was selected from a natural biofilm by its capability to produce extracellular polymeric substances (EPS). The EPS had an average molecule size of 15.278 μm and exhibited characteristic diffraction peaks at 5.985°, 9.150° and 22.823°, with <i>d-</i>spacings of 14.76661, 9.29989 and 3.89650 Å, respectively. The Fourier-transform infrared spectroscopy (FTIR) spectrum revealed aliphatic methyl, primary amine, halide groups, uronic acid and saccharides. Gas chromatography mass spectrometry (GCMS) confirmed the presence of arabinose, galactose, glucose and mannose. <sup>1</sup>HNMR (nuclear magnetic resonance) revealed functional groups characteristic of polysaccharides. The EPS were amorphous in nature (<i>CI<sub>xrd</sub></i> 0.092), with a 67.37% emulsifying activity, thermostable up to 250°C and displayed pseudoplastic rheology. MALDI-TOF–TOF analysis revealed a series of masses, exhibiting low-mass peaks (<i>m/z</i>) corresponding to oligosaccharides and higher-mass peaks for polysaccharides consisting of different ratios of pentose and hexose moieties. This is the first report of a detailed characterisation of the EPS produced by <i>V. parahaemolyticus</i>, which could be further explored for biotechnological and industrial use.</p> </div>