Screening and Optimization of High-efficiency Demineralization Bacterial Strains for Shrimp Shell Fermentation

Shrimp shells are currently the primary source of chitin, and demineralization of shrimp shells is a key step in the preparation of chitin. In this study, two acid-producing strains, GXUN-XS3 and GXUN-XS8, were isolated from abandoned shrimp ponds. They were identified through morphological and molecular methods. The optimal fermentation conditions were optimized using single-factor and response surface experiments. SEM analysis was used to characterize the fermentation products. The results showed that the isolated strains GXUN-XS3 and GXUN-XS8 were identified as Enterococcus faecalis and Exiguobacterium aestuarii, respectively. The optimized GXUN-XS3 was fermented in a medium containing 2% shrimp shell powder, 3% glucose, and 1% sodium chloride at a temperature of 30.5 ℃, an initial pH of 5.6, and an inoculum size of 3.3% for 3 days. The demineralization of shrimp shell reached 96.09%, which was an increase of 6.29% compared to before optimization. The optimized GXUN-XS8 fermented in a medium containing 2% shrimp shell powder, 2% maltose, and 1% sodium chloride at a temperature of 30.7 ℃, an initial pH of 5.7, and an inoculum size of 3.9% for 4 days. The demineralization of shrimp shell reached 95.73%, which was an increase of 6.17% compared to before optimization. SEM analysis revealed that the products had a fibrous structure with pores, more intact than industrial chitin produced by acid-alkali methods. This study provides microbial resources and references for the microbial fermentation degradation of shrimp shell waste.