Figure 1.

The effect of chitin/protein ratio. The chitin including two forms of α-chitin and β-chitin were mixed with free protein (casein) with six ratios of 1/7, 2/6, 4/4, 5/3, 6/2, and 7/1 (w/w) and used as the sole carbon and nitrogen source with the concentration of 1.5% (w/v). The fermentation was performed at the conditions at 30 °C in 1 d, and then at 25 °C in next 2 d, shaking speed of 150 rpm, and a ratio volume of medium: flask of 1:2.5 (v/v).