The ability of six protease-producing Bacillus species (Bacillus pumilus A1, Bacillus mojavencis A21, Bacillus
licheniformis RP1, Bacillus cereus SV1, Bacillus amyloliquefaciens An6 and Bacillus subtilis A26) to ferment
media containing only shrimp shell waste, for chitin extraction, was investigated. More than 80%
deproteinization was attained by all the strains tested. However, demineralization rates not exceeding
67% were registered. Cultures conducted in media containing shrimp shell waste supplemented
with 5% (w/v) glucose were found to remarkably promote demineralization efficiency, without affecting
deproteinization rates. The antioxidant activities of hydrolysates, at different concentrations, produced
during fermentation in medium supplemented with glucose, were determined using different tests:
1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging method, reducing power assay and chelating
activity. All hydrolysates showed varying degrees of antioxidant activity. Hydrolysate produced by B.
pumilus A1 exhibited the highest DPPH radical scavenging activity, with an IC50 value of 0.3 mg/ml. Highest
reducing power (DO 700 nm = 1.55 at 1.5 mg/ml) and metal chelating activity (98% at 5 mg/ml) were
obtained with B. pumilus A1 and B. licheniformis RP1 hydrolysates, respectively.