Optimisation of thermostable exopolysaccharide production from Enterococcus mundtii A2 isolated from camel milk and its structural characterisation

Abstract

Exopolysaccharide (EPS) production from Enterococcus mundtii A2 isolated from camel milk was investigated using a customised MRS medium and response surface methodology (RSM). Screening of variables including carbon and nitrogen sources, pH, and time showed that EPS production was not directly related to growth rate. Using central composite design, the optimised conditions affecting EPS production were maltose, yeast extract, and an initial pH of 5, resulting in a maximum yield of 382.27 mg L−1 after a 16-h fermentation period. The purified EPS was characterised using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray, and thermal-gravimetric analysis. The EPS exhibited specific morphology and thermal stability up to 200 °C. Moreover, extracted EPS showed the ability to reduce adhesion rates of pathogens to stainless steel.