The current study has been designed to investigate the possible biodegradation of native keratin by bacteria isolated from chicken feathers collected from chicken farms in and around Sivakasi. Out of 28 bacterial isolates, two species showed different degrees of keratinolytic activity, with Bacillus cereus FJ 377887 and Bacillus thuringiensis FJ 377886 showing the highest keratinase productivity (20.15 U/ml) as well as the highest value of specific activity for keratinase (165.90 U/mg protein) indicating a great degree of purity for the enzyme. Our present study indicates that the highest production of keratinase by Bacillus cereus and Bacillus thuringiensis was recorded at pH 8, 9 and a temperature of 35 °C, during a period of 48 days. In addition to that the optimal value of ionic strength for keratinase production was 100 mM NaCl. Monitoring the influence of constituents deprivation from basal salt medium on production of keratinase enzyme showed that K+, Fe2+, Mg2+, Ca2+ and Zn2+ were necessary for keratinase production. Sulphur deficiency has no significant influence on keratinase production. Keratinase activity of Bacillus cereus and Bacillus thuringiensis showed that, the optimal values of temperature and ionic strength were 35–40 °C and 80 mM NaCl, separately. The optimum pH range was (9–10). These promising findings demonstrate a high potentiality of Bacillus cereus and Bacillus thuringiensis enzyme in keratin proteolysis and lead to act as Plant growth promoting bacteria, feed additives, stain remover, goat dehairing suggesting that keratinase producing isolates of Bacillus cereus and Bacillus thuringiensis may be appropriate as a biodegradation agent.