Continuous Production of Chitin Oligosaccharides Utilizing an Optimized Enzyme Production-Adsorption-Enzymolysis-Product Separation (EAES) System

Abstract

Chitin oligosaccharide (CHOS) is a chitin derivative with excellent biological activities. Enzymatic hydrolysis of chitin-rich biomass into CHOS is a hot topic in research on the high-value utilization of chitin resources. The disadvantages of complex preparation and purification processes and the high cost of chitin-degrading enzymes limit large-scale enzymatic production and application of CHOS. In this study, the activity of chitinase increased from 1.8 U/mL to 3.52 U/mL by 94.4% after optimizing the carbon and nitrogen source of Chitiniphilus sp. LZ32 fermentation. An enzyme production-adsorption-enzymolysis-product separation (EAES) system was constructed using fermentation, an adsorption purification module, and a product ultrafiltration module of a chitin-degrading enzyme. CHOS production by continuous enzymatic hydrolysis was performed in an EAES system using housefly larval powder (HLP) as the substrate. After the C. sp. LZ32 fermentation broth was circulated in the adsorption module for 90 min, the adsorption rate of the chitin-degrading enzyme reached more than 90%. The ultrafiltration module effectively separated CHOS at an operating pressure of 2 bar. Four batches of CHOS were produced in the EAES system using repeated batch fermentation. The running time of a single batch decreased from 115 h in the first batch to 48 h, and the CHOS output of each batch gradually increased. The total CHOS output was 61 g, and the production efficiency was 0.24 g/h. The CHOS produced by the EAES system (ECHOS) has high antioxidant activity. In this study, the EAES system was used to simplify the purification and separation steps of CHOS preparation, and the continuous production of CHOS was realized, which has potential application prospects in the field of green CHOS production.