To overcome the problems of chemical treatments,
different microorganisms7–9 and proteolytic enzymes10,11
were used to remove the proteins and mineral content.
During fermentation with microbes, deprotenisation
takes place by the activity of proteases in the microorganisms
and demineralization by the acid produced
by the microorganisms during fermentation.12
Commercial bacterial proteases are derived from
Bacillus broth.13 B. subtilis, the commercial starting
material, contains a neutral protease, that is, characterized
by its pH activity and neutral stability.14 Zinc is
essential for catalytic activity and calcium is required
to maintain the structural rigidity of the enzyme. Many
reports have demonstrated the application of proteases
for the degradation of proteinaceous waste to useful biomass.
15–17 B. subtilis and B. firmus are the most common
exploited species. Many authors14,18 reported the application
of B. subtilis for deprotenisation of crustacean
waste to produce chitin.