One-step bio-extraction of chitin from shrimp shells by successive co-fermentation using Bacillus subtilis and Lactobacillus plantarum

Abstract

Chitin was bio-extracted in one-step from shrimp shells by successive co-fermentation using Bacillus subtilis and Lactobacillus plantarum in this study. To construct this co-fermentation system, B. subtilis was first cultured for 3 days for deproteinization (DP), and then L. plantarum was inoculated for demineralization (DM). After 6 days of co-fermentation, the final DP and DM efficiency reached 94.1% and 96.3%, respectively. The molecular weight, degree of acetylation, and crystalline index of chitin were reduced by 9.8, 5.6 and 1.4% with the DP time of 2 days extending to 3 days. Meanwhile, L. plantarum instead of B. subtilis became the dominant bacterium on day 5 of co-fermentation, with L. plantarum count of 6.19 log CFU/mL and lactic acid concentration of 28.22 g/L, respectively. The chitin prepared in this study exhibited similar structural characterization as commercial chitin. One step successive co-fermentation was a simple and feasible approach for high-quality chitin preparation.Industrial relevance: This study establishes one-step bio-extraction of chitin from shrimp shells by successive co-fermentation using B. subtilis followed by L. plantarum. One-step successive co-fermentation simplifies the intermediate processes of conventional two-step fermentation for extracting chitin. DP and DM happen during the entire co-fermentation period, which helps to achieve satisfactory DP and DM efficiency. This innovative yet simple method provides more possibilities for the biotechnological production of chitin on an industrial scale.