The freeze dried samples were dissolved in ultrapure water and
analysed by gel permeation chromatography (GPC) to determine
the yield of the isolated EPS. The GPC system consisted of a PL
aquagel-OH MIXED-H 8 μm, 300×7.5 mm column, connected with a
PL aquagel-OH 8 μm, 50×7.5 mm guard column. The EPS was
detected using a RI detector, at an internal temperature of 40 °C;
50 μL of sample was injected. The separation was carried out with
HPLC grade water (Fisher Scientific, Loughborough, UK) at a flow
rate of 0.4 mL min−1. The EPS concentration (mg L−1) was determined
using a linear regression equation constructed using dextran
as standard (150 kDa; Sigma-Aldrich, UK).