In contrast the OD was only 0.123 (i.e. 0.369 × 108 cells/mL) for the 0.1% chitosan treated samples, indicating inhibition of cell growth. While with 0.1% chitin treated samples the maximum OD was slightly higher at 0.264 (i.e. 0.792 × 108 cells/mL) and 0.22 (i.e. 0.66 × 108 cells/mL) for B. subtilis and B. cereus, respectively.