Abstract: In order to improve the feather keratin degrading efficiency by the strain Bacillus coagulans X3, the keratinase characteristics and feather keratin degrading effect were studied. Results showed that the optimal temperature and pH were 60℃ and 7.0～8.0, and it had good thermal stability from 70～80℃. Ca2+ and Mn2+ could greatly enhance the activity of keratinase，while its activity was strongly inhibited by Cu2+ and Ni2+. The keratinase activity showed no significantly difference with the addition of Na+, Mg2+ and Fe3+. Furthermore, the keratinase activity was inhibited by phenyl methyl sulfonyl fluoride (PMSF) and ethylene diamine tetra acetic acid (EDTA). However, β-mercaptoethanol and dithiothreitol (DTT) increased the relative enzyme activity. The enzyme could remain stable in the presence of sodium dodecyl sulfate (SDS) and dimethyl sulfoxide (DMSO). After the optimization of feather degradation conditions, the total content of free amino acids was as high as 4.322 6 mg/mL, and the main free amino acids were valine, phenylalanine, tyrosine and glutamic acid. The results can be a technological support to the utilization of Bacillus coagulans X3.
Key words: Bacillus coagulans; keratinase; enzyme characteristics; feather keratin; free amino acid
（Acta Laser Biology Sinica, 2022, 31(3): 250-255）