Figure 4. Effect of growth substrate concentration on protease production by Chryseobacterium sp. kr6 at 30ºC and initial pH 7.0 in media containing different amounts of raw feathers (circles), feather meal (squares) or soy meal (triangles) after 24 h (black symbols) and 48 h (white symbols) cultivation. Points are the means ± s.e.m. of three independent experiments.