Chitin from Penaeus merguiensis via microbial fermentation processing and antioxidant activity

The ability of three proteases producing bacteria such as Pseudomonas aeruginosa, Serratia marcescens, and Bacillus pumilus on the demineralization and deproteinzation efficiency of shrimp waste, for chitin extraction, was investigated. Statistical analysis of data was showed a significant difference between the percentage of demineralization and deproteinization in different bacteria species (p < 0.05). The highest deproteinization (74.76%) and demineralization rate (78.46%) was obtained with P. aeruginosa and the lowest was observed in the treatment of S. marcescens. Then, chitin was converted to chitosan by deacetylation in the presence of NaOH 50%. The antioxidant activity of chitosan solution was determined using different tests. The highest activity (DO 700 nm = 0.74, DO 695 nm = 0.31) was observed for chitosan sample at concentration of 1000 μg/ml. The antioxidant potential of the hydrolysates was also evaluated. The highest reducing power in a volume of 400 μl hydrolysate of S. marcescens and the highest total antioxidant capacity in a volume 100 μl hydrolysate of B. pumilus were observed. These results indicated that the P. aeruginosa bacterium in comparison with other bacterial strains, higher ability to remove proteins and mineral from shrimp waste. Therefore, the use of this bacterium is recommended for protein and mineral removal from marine crustaceans.