Viable cells (log CFU/ml) were
enumerated on tryptic soy agar (Difco) or MRS agar
(for lactic acid bacteria) by pour plating 1 ml of serial
dilutions of MBH or MRS broth followed by incubation
at 37 C for 48 h. In studies on effect of chitosan
solvents (acetic, lactic, formic, propionic, and ascorbic
acids) and pH (4.5, 5.0, 5.5, and 5.9; adjusted with 1
N HCl and 1 N NaOH), chitosan solution (1% in 1%
organic acids and 1% acetic acid, respectively) was
added to MHB or MRS broth to give a final chitosan
concentration of 0.03% (w/v).