Extraction of chitosan and its oligomers from shrimp shell waste, their characterization and antimicrobial effect

The present study was performed to utilize the shrimp shell waste for chitin and chitosan production, characterization by Fourier transform infrared (FT-IR) technique and to evaluate the antimicrobial effects of chitosan oligomers produced by depolymerization of chitosan by nitrous acid.

Chitosan was extracted from the shrimp shell waste by the chemical method and characterized by FT-IR. Chitooligomers were produced by depolymerising chitosan using nitrous acid, and the chitooligomers were tested for antimicrobial effect against four gut pathogenic organisms, i.e., Enterobacter aerogen (National Collection of Dairy Culture [NCDC] 106), Enterococcus faecalis (NCDC 119), Escherichia coli (NCDC 134), and Staphylococcus aureus (NCDC 109) by well diffusion method using Muller-Hinton agar. A pure culture of pathogenic organisms was collected from NCDC, ICAR-National Dairy Research Institute, Karnal.

Extracted chitosan characterized by FT-IR and chitooligomers demonstrated antimicrobial effect against four gut pathogenic organisms used in this study. Zone of inhibitions (mm) were observed in E. faecalis (13±0.20), E. coli (11.5±0.4), S. aureus (10.7±0.2), and E. aerogen (10.7±0.3). E. faecalis showed larger inhibition zone as compared to all other organisms and inhibitions zones of E. aerogen and S. aureus were comparable to each other.

Shrimp waste can be utilized for chitosan production, and the chitooligomers can be used as feed additive for gut health enhancement and have potential to replace antibiotics from the feed. Along with value addition pollutant load could be reduced by waste utilization.