An Exochitinase with N-Acetyl-β-Glucosaminidase-Like Activity from Shrimp Head Conversion by Streptomyces speibonae and Its Application in Hydrolyzing β-Chitin Powder to Produce N-Acetyl-d-Glucosamine.

Thi Ngoc Tran,Anh Dzung Nguyen,San-Lang Wang,Minh Trung Nguyen,Thi Phuong Khanh Vo,Chien Thang Doan,Van Bon Nguyen

doi:10.3390/polym11101600

Thi Ngoc Tran, Anh Dzung Nguyen + Show 5 more

Open Access

https://doi.org/10.3390/polym11101600

Copy DOI

Journal: Polymers	Publication Date: Sep 30, 2019
Citations: 23	License type: CC BY 4.0

Affiliation: Thai Nguyen University, Tamkang University

Abstract

Marine chitinous byproducts possess significant applications in many fields. In this research, different kinds of fishery chitin-containing byproducts from shrimp (shrimp head powder (SHP) and demineralized shrimp shell powder), crab (demineralized crab shell powder), as well as squid (squid pen powder) were used to provide both carbon and nitrogen (C/N) nutrients for the production of an exochitinase via Streptomyces speibonae TKU048, a chitinolytic bacterium isolated from Taiwanese soils. S. speibonae TKU048 expressed the highest exochitinase productivity (45.668 U/mL) on 1.5% SHP-containing medium at 37 °C for 2 days. Molecular weight determination analysis basing on polyacrylamide gel electrophoresis revealed the mass of TKU048 exochitinase was approximately 21 kDa. The characterized exochitinase expressed some interesting properties, for example acidic pH optima (pH 3 and pH 5–7) and a higher temperature optimum (60 °C). Furthermore, the main hydrolysis mechanism of TKU048 exochitinase was N-acetyl-β-glucosaminidase-like activity; its most suitable substrate was β-chitin powder. The hydrolysis experiment revealed that TKU048 exochitinase was efficient in the cleavage of β-chitin powder, thereby releasing N-acetyl-d-glucosamine (GlcNAc, monomer unit of chitin structure) as the major product with 0.335 mg/mL of GlcNAc concentration and a yield of 73.64% after 96 h of incubation time. Thus, TKU048 exochitinase may have potential in GlcNAc production due to its N-acetyl-β-glucosaminidase-like activity.

Highlights

Chitin is a straight-chain polymer of N-acetyl-d-glucosamine (GlcNAc) unit with β-1,4 linkage, which is a very common polysaccharide in the world, second only to cellulose
One of the most important applications of chitinase is its use in hydrolyzing chitin/chitosan to
One of the most important applications of chitinase is its use in hydrolyzing chitin/chitosan to produce bioactive chitooligosaccharides and GlcNAc

Summary

Introduction

Chitin is a straight-chain polymer of N-acetyl-d-glucosamine (GlcNAc) unit with β-1,4 linkage, which is a very common polysaccharide in the world, second only to cellulose. Strong alkali and acids are used to remove the protein and mineral salts from these resources to produce chitin As a result, these chemical procedures encounter several drawbacks when these chemical procedures are applied, such as the release of alkaline wastewater containing a high concentration of protein [11]. These chemical procedures encounter several drawbacks when these chemical procedures are applied, such as the release of alkaline wastewater containing a high concentration of protein [11] In green applications, those chitin-containing byproducts could be used as the nutrition sources for microorganism bioconversion to produce numerous bioactive compounds, for instance, proteases [9,11,12], chitinases/chitosanases [2,4,13,14,15,16,17,18], α-glucosidase inhibitors [19,20,21,22,23,24,25], exopolysaccharide [26,27,28], tyrosinase inhibitors [29,30], or chitin [1,31,32,33]

Methods

Results

Conclusion