Production of Chitin and Chitosan from Shrimp Shell Wastes Using Co-Fermentation of Lactiplantibacillus plantarum PTCC 1745 and Bacillus subtilis PTCC 1720

Background and Objective: Disposal of fishery wastes is one of the environmental challenges. Converting wastes into valuable products is an economical solution to solve this environmental problem. One of the wastes of fishery products is shrimp shell waste, which contains large quantities of chitin. Chitin and its derivative, chitosan, include several uses in various industries, especially the food industry. The aim of the present study was to extract chitin from shrimp shell wastes using co-fermentation with mixed microbial cultures. Chitosan production by deacetylation of chitin using various concentrations of NaOH was another aim of this study. Material and Methods: Batch fermentation was carried out to extract chitin from the shrimp shell using mixed cultures of two microorganisms, Lactiplantibacillus plantarum PTCC 1745 and Bacillus subtilis PTCC 1720. The Logistic model was used to assess the microbial growth rate. To prepare chitosan from chitin, deacetylation was carried out using NaOH solution. Morphological structures of the chitin and chitosan were studied using scanning electron microscopy. Functional groups of the synthesized chitin and chitosan were assessed using Fourier transform infrared spectroscopy. Results and Conclusion: High levels of demineralization and deproteinization were achieved using co-fermentation with the mixed microbial populations at 60 g.l-1 of glucose concentration. Chitin was produced with high purity and the protein and ash contents included 1.43 and 1.26%, respectively. Data predicted by the Logistic model were fairly matched the experimental data. A maximum cell growth rate of 0.065 (h-1) was achieved at 60 g.l-1 of initial glucose concentration at 35 °C. The optimal value of deacetylation (88.2%) was achieved using 50% NaOH solution at 100 °C. The results showed that the use of mixed culture of acid-producing and proteolytic microorganisms is highly effective for extracting chitin from shrimp shell waste.