Surface defects due to bacterial residue on shrimp shell

Abstract

The changes in the surface chemistry and morphological structure of chitin forms obtained from shrimp shells (ShpS) with and without microorganisms were evaluated. Total mesophilic aerobic bacteria (TMAB), estimated Pseudomonas spp. and Enterococcus spp. were counted in Shp-S by classical cultural counting on agar medium, where the counts were 6.56 ± 0.09, 6.30 ± 0.12, and 3.15 ± 0.03 CFU/g, respectively. Fourier Transform Infrared (FTIR) Spectroscopy and Scanning Electron Microscopy (SEM)/Energy dispersed X-ray (EDX) were used to assess the surface chemistry/functional groups and morphological structure for ChT_free (non-microorganism), and ChT_mo (with microorganisms). ChT_free FTIR spectra presented a detailed chitin structure by OH, NH, and CO stretching vibrations, whereas specific peaks of chitin could not be detected in ChT_mo. Major differences were also found in SEM analysis for ChT_free and ChT_mo. ChT_free had a flat, prominent micropore, partially homogeneous structure, while ChT_mo had a layered, heterogeneous, complex dense fibrous, and lost pores form. The degree of deacetylation was calculated for ChT_free and ChT_mo according to FTIR and EDX data. The results suggest that the degree of deacetylation decreases in the presence of microorganisms, affecting the production of beneficial components negatively. The findings were also supported by the molecular docking model.

Keywords: Chitin; Docking; FTIR; Microbiological analyzes; SEM/EDX; Shrimp shell.