In order to improve the production of bacterial keratinase utilizing the poultry
feathers as an environmental waste, some nutritional and environmental factors were
considered in a low cost medium. These factors are substrate concentration (chicken
feather), '. pH of the cultural medium, growth temperature, inoculum size and agitation
effect as well. These experiments were carried out !-Ising two bacterial strains namely
Bacillus licheniforrnis CF-26 and Bacillus licheniforrnis PWD-28, Obtained results
showed that both tested strains produced the maximum keratlnase with 2% feather
as carbon and nitrogen sources after the 9th' day of fermentation. The maximum
production of keratinase was found at pH value . of 8.0 for B. licheniforrnis CF-26,
while pH 9.0 was the best for B. 1i9heniforrnis PWD-28. For the growth temperature at
pH 7.0 of the strains No .. CF-26; the keratinase activity was 3-5 fold higher at 40°C
than that obtained at 55·C. At pH 9.0., opposite results were obtained by 1.9 fold. In
case of the strain No. PWD-28, the production of keratinase at 40·C was lower at pH
7.5 than its-value. obtained at pH 9.0 by 1.2 fold after the 3'd day of fermentation. The
inoculum size of'10% was the optimal for the two tested bacterial strains. In addition,
the static cultivation gave higher value of keratinase activity than that of shake
culture. The growth· of bacterial strains on chicken feather was also followed by'
. -measuring the activity of proteinase, the total soluble proteins and the obtained free .
amino acids as well. .