The pellets obtained were washed twice in 15 mL 20 g L−1trisodium citrate (pH 7.5) (Sigma–Aldrich, St. Louis, USA) thenresuspended in 15 mL sterile water and 10-fold diluted. Sub-sequently, 1 mL of each sample was used for viability countsaccording to the manufacturer’s instructions. Samples stained withLIVE/DEAD®were then filtered onto black polycarbonate filters(0.2 m pore size) (Millipore Corp., Billerica, MA, USA), visualisedby an epifluorescence microscope (Nikon 80i, Tokyo, Japan) andcounted as described by Bottari et al. [2]. Three separate countswere performed for each sample. Results were expressed as total,viable and non-viable cells (mL−1or cells g−1).