Proteases Production and Chitin Preparation from the Liquid Fermentation of Chitinous Fishery By-Products by Paenibacillus elgii.

Dan-Hsin Lee,Anh Dzung Nguyen,Van Bon Nguyen,Thi Ngoc Tran,Chien Thang Doan,San-Lang Wang,Chuan-Lu Wang

doi:10.3390/md19090477

Abstract

Chitinous fishery by-products have great application in the production of various bioactive compounds. In this study, Paenibacillus elgii TKU051, a protease-producing bacterial strain, was isolated using a medium containing 1% squid pens powder (SPP) as the sole carbon/nitrogen (C/N) source. P. elgii TKU051 was found to produce at least four proteases with molecular weights of 100 kDa, 57 kDa, 43 kDa, and 34 kDa (determined by the gelatin zymography method). A P. elgii TkU051 crude enzyme cocktail was optimally active at pH 6–7 and 60 °C. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and α-glucosidase inhibitory activity of the hydrolysates obtained from the hydrolysis of shrimp shell powder, shrimp head powder, shrimp meat powder, fish head powder and soya bean powder catalyzed by the P. elgii TkU051 crude enzyme cocktail were also evaluated. P. elgii TKU051 exhibited a high deproteinization capacity (over 94%) on different kinds of shrimp waste (shrimp heads and shells; fresh and cooked shrimp waste; shrimp waste dried by oven and lyophilizer), and the Fourier-transform infrared spectroscopy profile of the chitin obtained from the deproteinization process displayed the characteristic of chitin. Finally, the obtained chitin exhibited an effect comparable to commercial chitin in terms of adsorption against Congo Red (90.48% and 90.91%, respectively). Thus, P. elgii TKU051 showed potential in the reclamation of chitinous fishery by-products for proteases production and chitin extraction.

Highlights

Chitin is a natural biological polymer present in the exoskeleton of crustaceans such as shrimps, crabs, and cephalopods, the pen of squids and the cell wall of fungi
There are only a few reports on the application of Paenibacillus strains for deproteinization of chitinous material; this study suggests that P. elgii TKU051 can be used for the deproteinization of different kinds of shrimp waste
The use of these materials for enzyme and chitin production via a microbial conversion method could increase their economic value and help in preventing pollution caused by the acid/alkali used for demineralization/deproteinization

Summary

Introduction

Chitin is a natural biological polymer present in the exoskeleton of crustaceans such as shrimps, crabs, and cephalopods, the pen of squids and the cell wall of fungi. The abundance of chitin in nature is second only to cellulose [1] and is mainly composed of. The annual production of shrimp and crab shell waste is 6–8 million tons globally [2]. The waste of shrimp and crab shells containing chitin is one of the main sources of chitin extraction. The industrial extraction of chitin from shrimp and crab shells is broadly done in two steps: deproteinization with NaOH and demineralization with HCl. the use of chemical methods to extract chitin causes a high level of pollution.

Methods

Results

Conclusion