Cellulase activity. The cells were grown in medium
supplemented with 0.5% carboxymethylcellulose [49].
The plates were flooded with 1 mg/ml of Congo red
solution, which was poured off after 15 min. The plates
were then flooded with 1 M NaCl for 15 min. Positive
cellulase activity was defined as a clear halo around the
colony on a red background