Preparation of feather digests as fertilizer with Bacillus pumilis KHS-1

The present study was untaken to assess the capacity of Bacillus pumilis KHS-1 to grow on chicken flour and to prepare feather digest as fertilizer. To increase keratinolytic activity, the addition of cysteine (5.0 mM) showed the highest keratinolytic activity (245 unit) among the reducing agents tested. The production of soluble protein (feather digests) paralleled the tendency to the production of keratinolytic protease. In the growth curve of B. pumilis KHS-1 at 30°C in the feather medium with 5 mM cysteine, the maximum keratinolytic activity of B. pumilis was about 161 units/ml after 84 h of incubation. The maximum enzyme activities were observed at the late logarithmic growth phase, and remained thereafter with little changes. Using 27-day plant growth assays on carrot and Chinese cabbage, feather digests and reference fertilizer were compared. In terms of the length and the weight of the above-ground vegetations, feather digests showed the same effect as that of the fertilizer. Therefore, our investigation shows that the feather digests can be used in agriculture.