Production of Thermophilic Chitinase by Paenibacillus sp. TKU052 by Bioprocessing of Chitinous Fishery Wastes and Its Application in N-acetyl-D-glucosamine Production.

Chien Thang Doan,Thi Ngoc Tran,San-Lang Wang

doi:10.3390/polym13183048

Abstract

The bioprocessing of chitinous fishery wastes (CFWs) to chitinases through fermentation approaches has gained importance owing to its great benefits in reducing the enzyme production cost, and utilizing chitin waste. In this work, our study of the chitinase production of Paenibacillus sp. TKU052 in the presence of different kinds of CFWs revealed a preference for demineralized crab shells powder (deCSP); furthermore, a 72 kDa chitinase was isolated from the 0.5% deCSP-containing medium. The Paenibacillus sp. TKU052 chitinase displayed maximum activity at 70 °C and pH 4–5, while Zn2+, Fe3+, Triton X-100, Tween 40, and SDS exerted a negative effect on its activity, whereas Mn2+ and 2-mercaptoethanol were found to potentially enhance the activity. Among various kinds of polysaccharide, Paenibacillus sp. TKU052 chitinase exhibited the best catalytic activity on colloidal chitin (CC) with Km = 9.75 mg/mL and Vmax = 2.43 μmol/min. The assessment of the hydrolysis of CC and N-acetyl chitooligosaccharides revealed that Paenibacillus sp. TKU052 chitinase possesses multiple catalytic functions, including exochitinase, endochitinase, and N-acetyl-β-D-glucosaminidase activities. Finally, the combination of Paenibacillus sp. TKU052 chitinase and Streptomyces speibonae TKU048 N-acetyl-β-D-glucosaminidase could efficiently convert CC to N-acetyl-D-glucosamine (GlcNAc) with a production yield of 94.35–98.60% in 12–24 h.

Highlights

Chitin is a linear polysaccharide made of N-acetyl-D-glucosamine (GlcNAc) units linked through the β-1,4-glycosidic linkages [1,2]
This “green technique” has shown great potential owing to the capability of microbes in utilizing chitinous fishery wastes (CFWs) as appropriate carbon and nitrogen (C/N) sources for producing various metabolites, such as enzymes [11,12,13,14], antioxidants [15], enzymes inhibitors [16,17], antimicrobial agents [18], etc
TKU052 created a zone of hydrolysis on the colloidal chitin (CC) plate after three days of incubation (Figure 1), indicating that this strain secretes extracellular chitinolytic enzymes to degrade the surrounding CC

Summary

Introduction

Chitin is a linear polysaccharide made of N-acetyl-D-glucosamine (GlcNAc) units linked through the β-1,4-glycosidic linkages [1,2]. CFWs mainly contain chitin and proteins, which can directly serve as nutrient components for microbial fermentation [7,8,9,10]. This “green technique” has shown great potential owing to the capability of microbes in utilizing CFWs as appropriate C/N sources for producing various metabolites, such as enzymes [11,12,13,14], antioxidants [15], enzymes inhibitors [16,17], antimicrobial agents [18], etc. The bioremediation and chitin waste utilization aspects may be resolved through this technique [19]

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Conclusion