Preparation of chitosan oligosaccharides from chitosan of tenebrio molitor and its prebiotic activity

This study aimed to establish the optimal production conditions for mealworm chitosan oligosaccharides (MCOS) using the response surface methodology and measure the prebiotic effect of MCOS prepared on cecal microbiota through in vitro anaerobic fermentation. The optimal conditions for MCOS production using chitosanase were 2.5% substrate, 30 mg/g enzyme, and 6 h reaction time. Matrix-assisted laser desorption ionization-time of flight mass spectrometry, Fourier transform infrared spectroscopy, and in vitro assays to confirm that the chemical structure and physicochemical properties of MCOS are similar to those of commercially available chitosan oligosaccharides. The growth of Lactobacillus acidophilus, Lacticaseibacillus casei, and Bifidobacterium bifidum was increased by MOCS and confirmed that the prebiotic effect of MCOS was significant in a concentration-dependent manner. The addition of 1% and 2% MCOS to in vitro anaerobic fermentation resulted in changes in the content of short-chain fatty acids (SCFAs) and an increase in Verrucomicrobiota abundance compared with the control. In the case of Romboutsia, Turicibacter, and Akkermansia, a significant increase was confirmed in the MCOS-containing groups compared to that in the control group. Compared to 2% MCOS, 1% MCOS more significantly affected Lactobacillus levels. MCOS produced by chitosanase under optimal conditions contains oligosaccharides with 2-6 degree of polymerization and exerts a prebiotic effect that affects changes in the SCFA content and microbiota composition in the cecum.