The biofilm formation was assessed on 12 well polystyrene (PS)
plates (Greiner Bio-One). Each well was filled with 1.5 ml of BHIMnG inoculated
with L. plantarum as described in the above paragraph and incubated
up to 72 h at 30 °C sealed with parafilm to avoid evaporation.
The biofilm formation was determined both by the CV assay and plate
counting to determine the number of culturable cells in the biofilm.
For this purpose, the medium was removed and the adhering cells in
each well were washed three times with 2ml of PBS and the remaining
biofilm was resuspended by scraping and rigorous pipetting in 2 ml of
PBS (Kubota et al., 2009; van der Veen and Abee, 2011). In addition,
the absence of clumps and cell aggregateswas confirmed by phase contrast
microscopy. Serial dilutions were prepared in PBS and plated on
MRS agar (Oxoid) and incubated at 30 °C for 48 h. Biofilm formation
was followed as a function of time (24, 48 or 72 h at 30 °C) and temperature
(20, 25, 30 and 37 °C for 72 h). All experiments involved three independent
biological replicates and each replicate included three
technical replicates.