Investigation on Production and Purification of Haloalkalophilic Organic Solvent Tolerant Protease from Marine Shell Waste and its Bioconversion to Chitin by Aquatic Bacillus sp. APCMST-CS4

The current increase in the bulge amount of marine fish wastes produced by the marine industries has led to search for new efficient and judicious disposal methods. Hence the present study was undertaken on production and purification of halophilic organic solvent tolerant protease (HOSP) from marine Bacillus sp. APCMST-CS4 using marine shell wastes as substrate. Statistical media obtained optimization inferred that, anchovy powder (20.00 g/L), crab shell powder (12.5 g/L), NaCl (100.00 g/L), and CaCl 2 (3.00 g/L) favored maximum protease activity (1,398.20 U/mL) and it was found to be an alkaline HOSP. This HOSP was purified to 8.10 fold with 29.52 U/mg specific activity and its molecular weight was 21 kDa. Further this HOSP was tolerant to temperature (60 °C), pH (8), NaCl (2.5 M), metals, surfactants, solvents and commercial detergents and exhibited maximum activity. The serine and metalloprotease inhibitors were highly inhibited the activity of HOSP; hence this protease was referred as serine metalloprotease. The candidate strain had the ability to deproteinize (80.17 %) the crab shell waste and also displayed maximum antioxidant activity. FTIR and 13 C CP/MAS NMR study revealed the presence of pure ∝-chitin in the HOSP fermented crab shell waste and it emerged as a potential alternate method for the production of chitin. Graphical Abstract