Abstract
This study was designed with the aim to produce microbial proteases in presence of speckled shrimp by-product. For this reason, three strains belonging to Bacillus genus, namely, Aeribacillus pallidus VP3, Lysinibacillus fusiformis C250R, and Anoxybacillus kamchatkensis M1V were studied under co-culture procedure. A Taguchi L27 experimental design was applied to optimize the co-culture parameters. The experimental design was built with 9 factors (by-product powder concentration, the pH of the medium, the temperature, the sucrose concentration, the agitation speed, the inoculum sizes of VP3, M1V, and C250R strains, and the culture volume) at three different levels. The obtained results showed that a total protease activity of 8,182 U/mL could be achieved after 24 h of incubation in presence of 20 g/L shrimp by-product and 10 g/L sucrose, at an initial pH of 7, a 40°C temperature and absorbance, at 600 nm, of inoculum sizes of 0.1, 0.3, and 0.1 for VP3, M1V, and C250R strains, respectively. The agitation was set at 200 rpm, and the final volume was 25 mL. Taguchi's design allowed the identification of temperature, the inoculum size for strain VP3, the inoculum size for strain M1V, and the final culture volume as the most influencing variables. A Box–Behnken design with 27 experiments was carried out for the optimization of these four selected factors. Following such design, the highest protease production reached was 11,300 U/mL. This yield was obtained in a final culture volume of 15 mL containing 20 g/L shrimp by-product powder and 10 g/L sucrose and inoculated with VP3, C250R, and M1V strains at 0.05, 0.1, and 0.2, respectively. The flasks were incubated at 45°C for 24 h with shaking at 200 rpm. The efficiency of chitin extraction by co-cultivation was investigated under the latter conditions. The chitin yield from shells by-product was 16.7%. Fourier-Transform Infrared (FTIR) analysis of the obtained chitin displayed characteristic profiles similar to that of the commercial α-chitin.
Highlights
Environmental pollution has lately become a great concern
Biotechnology has made possible to exploit marine biowastes for the recovery of natural macromolecules such as oils, antibiotics, enzymes, bioactive peptides, as well as gelatin, chitin, and its derivatives, which are with great interest at the pharmaceutical, biomedical, agricultural, and environmental sectors [4]
Erefore, the objectives of this study were the application of Taguchi and Box–Behnken designs to optimize the production of proteases by the co-cultivation of three proteolytic bacteria, Aeribacillus pallidus VP3, Lysinibacillus fusiformis C250R, and Anoxybacillus kamchatkensis M1V grown on medium containing shrimp Metapenaeus monoceros by-product, for chitin recovery
Summary
Environmental pollution has lately become a great concern. many industrial wastes have contaminated the natural environment, seriously threatening human lives. e released pollutants remain a serious problem in both industrialized and developing countries [1, 2]. e control of water pollution and the recovery of industrialBioMed Research International residues are important objectives in most countries. Environmental pollution has lately become a great concern. E released pollutants remain a serious problem in both industrialized and developing countries [1, 2]. E control of water pollution and the recovery of industrial. The processing and handling of marine by-products are being discussed. Marine by-products are nonedible parts of fish, crustaceans, or cephalopods including skin, heads, bones, internal skeletons, scales, tails, shells, and viscera, being thrown during industrial processing [3]. Biotechnology has made possible to exploit marine biowastes for the recovery of natural macromolecules such as oils, antibiotics, enzymes, bioactive peptides, as well as gelatin, chitin, and its derivatives, which are with great interest at the pharmaceutical, biomedical, agricultural, and environmental sectors [4]. Chitin, which is a polymer formed from a repeating unit of N-acetyl-D-glucosamine, is the second most abundant organic compound after cellulose
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