Mechano-Enzymatic Degradation of the Chitin from Crustacea Shells for Efficient Production of N-acetylglucosamine (GlcNAc)

Abstract

Chitin, the second richest polymer in nature, is composed of the monomer N-acetylglucosamine (GlcNAc), which has numerous functions and is widely applied in the medical, food, and chemical industries. However, due to the highly crystalline configuration and low accessibility in water of the chitin resources, such as shrimp and crab shells, the chitin is difficult utilize, and the traditional chemical method causes serious environment pollution and a waste of resources. In the present study, three genes encoding chitinolytic enzymes, including the N-acetylglucosaminidase from Ostrinia furnacalis (OfHex1), endo-chitinase from Trichoderma viride (TvChi1), and multifunctional chitinase from Chitinolyticbacter meiyuanensis (CmChi1), were expressed in the Pichia pastoris system, and the positive transformants with multiple copies were isolated by the PTVA (post-transformational vector amplification) method, respectively. The three recombinants OfHex1, TvChi1, and CmChi1 were induced by methanol and purified by the chitin affinity adsorption method. The purified recombinants OfHex1 and TvChi1 were characterized, and they were further used together for degrading chitin from shrimp and crab shells to produce GlcNAc through liquid-assisted grinding (LAG) under a water-less condition. The substrate chitin concentration reached up to 300 g/L, and the highest yield of the product GlcNAc reached up to 61.3 g/L using the mechano-enzymatic method. A yield rate of up to 102.2 g GlcNAc per 1 g enzyme was obtained.

Improving the efficiency and sustainability of chitin bioconversion through a combination of Streptomyces chitin-active-secretomes and mechanical-milling

“…36 In a different study, only a 20% chitin conversion was achieved (61.3 mg mL −1 GlcNAc from 300 mg mL −1 chitin) using liquid-assisted milling and reactive aging treatment of chitin in the presence of a synthetic cocktail of three recombinant enzymes (107.4 U Tv Chi1, 287.2 U Cm Chi1 and 143 U Of Hex1). 37 In contrast to these processes, the current method achieves a 65% chitin conversion rate with a relatively lower load of naturally produced Streptomyces sp. UH6 chitin-active-secretome.…”

Establishment of the colloidal chitin enzymatic hydrolysis conditions to obtain N-acetyl glucosamine

“…The yield and productivity of GlcNAc were calculated to compare with the highest data obtained in this study. Yu et al (2022) used a mechano-enzymatic treatment for the hydrolysis of shrimp and crab shells. The milling process, associated with a fungal enzymatic cocktail, produced the highest concentration of GlcNAc (61.3 mg/ml) and productivity (5.11 mg/mL * h) among the analyzed studies.…”

“…Shrimp and crab shellMechano-enzymatic hydrolysis N-acetylglucosaminidase (Ostrinia furnacalis)Yu et al, 2022 Endochitinase (Trichoderma viride)…”

The Prospect of Hydrolytic Enzymes from Bacillus Species in the Biological Control of Pests and Diseases in Forest and Fruit Tree Production

“…Chitinases hydrolyze the β-(1,4)-glycosidic linkage of the chitin polymer in the fungal cell walls and insect cuticles (mainly endo-and exo-cuticles) to release N-acetyl-dglucosamine (GlcNAc) and chitooligosaccharides units [84]. The mechanism of chitinolytic activity is achieved by endo-chitinases which cleave chitin polymers into the respective oligomers, exo-chitinase which catalyzes the breakdown of β-1,4-glycosidic bonds between the 2-GIcNAc and 3-GIcNAc residues to release chitobiose, and N-acetylglucosaminidase (NAGase) which cleaves the β-1,4-glycosidic bond at the end of the chitin chain to release GlcNAc [85][86][87]. Sometimes, these enzymes overlap with the activity of chitosanases which hydrolyze both chitosan (GlcN-GlcN linkages) and β-1,3and β-1,4-glucans [85][86][87].…”