2.3. Keratinase production under solid state fermentation (SSF)
2.3.1. Production under flask condition
The bacterial strain hsTKB2 was screened for extracellular keratinolytic
protease activity in SSF media. SSF was carried out by
taking 5 g of dry chicken feathers in a 250-mL Erlenmeyer flask to
which 5 mL mineral salt solution containing (%, w/v): KH2PO4 0.5,
MgSO4 0.2, NaCl 5, CaCO3 0.03 in distilled water was added to
adjust the 1:1 moisture level. The contents of the flasks were mixed
and autoclaved at 121 C for 20 min. The flasks were inoculated
using 1 mL of culture broth and incubated at 45 C for 120 h. To
extract the enzymes produced, 50 mL of distilled water was added
following incubation at room temperature with continuous shaking
at 200 rpm for 60 min. The feathers were removed by filtration and
the supernatant obtained after centrifugation of the filtrate
(8000 rpm; 10 min) was followed by dia-filtered using a 10 kDa
ultrafiltration membrane. The filtrate was used as a crude enzyme
for subsequent study.
Fig. 1. Conventional cleaning steps of the CIP process in dairy industries.