Abstract
Chitin and astaxanthin were extracted from shrimp shell wastes (SSW) by biological treatment using the Lactobacillus species and Bacillus subtilis. In order to look for optimal fermentation conditions, glucose concentration (10–24% w/v), shrimp shell concentration (5–12% w/v), and inoculum size (5–10% v/v) were optimized using statistical tools, namely the Plackett-Burman (PB) study followed by Response Surface Methodology (RSM) for B. subtilis based fermentation. Similarly, the glucose concentration (7–24% w/v), shrimp shell concentration (5–12% w/v) and incubation period (2–7 days) were optimized using PB and RSM studies using Lacticaseibacillus casei based fermentation. At the end of these fermentation studies from shrimp shells using 20% w/v glucose, 5% w/v SSW, 6.3% v/v inoculum of L. casei after 7 days of incubation, the optimal demineralization (DM) (67.23%), deproteinization (DP) (82.31%) and chitin yield (0.553 g/g) were obtained. The results also showed a direct correlation between the microbial strain used and maximum DM (79.17% using Lacticaseibacillus rhamnosus), maximum DP (69.8% using B. subtilis) and maximum chitin yield (0.665 g/g using L. rhamnosus) obtained after fermentation. Then, chitin and astaxanthin were extracted from the best fermented SSW and characterized using FTIR, XRD and HPLC. At the end, the degree of acetylation (74.76%) of fermented SSW was estimated from FTIR analysis and astaxanthin yield (0.36 mg/g) in fermented SSW was estimated by HPLC analysis.