title: Chitin extraction from crab shells by Bacillus bacteria. Biological activities of fermented crab supernatants.
abstract: Crab shells waste were fermented using six protease-producing Bacillus species (Bacillus subtilis A26, Bacillus mojavensis A21, Bacillus pumilus A1, Bacillus amyloliquefaciens An6, Bacillus licheniformis NH1 and Bacillus cereus BG1) for the production of chitin and fermented-crab supernatants (FCSs). In medium containing only crab shells, the highest demineralization DM was obtained with B. licheniformis NH1 (83±0.5%) and B. pumilus A1 (80±0.6%), while the highest deproteinization (DP) was achieved with A1 (94±1%) followed by NH1 (90±1.5%) strains. Cultures conducted in medium containing crab shells waste supplemented with 5% (w/v) glucose, were found to remarkably promote demineralization efficiency, and enhance slightly deproteinization rates. FTIR spectra of chitins showed the characteristics bands of α-chitin. FCSs showed varying degrees of antioxidant activities which were in a dose-dependent manner (p<0.01). In fact, FCS produced by B. amyloliquefaciens An6 exhibited the highest DPPH free radical-scavenging activity (92% at 4 mg/ml), while the lowest hydroxyl radical-scavenging activity (60% at 4 mg/ml) was obtained with B. subtilis A26 hydrolysates. However, the highest reducing power (OD700nm=2 at 0.5 mg/ml) was obtained by B.amyloliquefaciens An6 hydrolysates. These results suggest that crab hydrolysates are good sources of natural antioxidants. Further, FCSs were found to exhibit antibacterial activity against Gram-positive and Gram-negative bacteria.
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, National School of Engineering of Sfax; University of Sfax, B.P. 1173, 3038 Sfax, Tunisia. Electronic address: hajjisawssen@yahoo.fr.
authors.forename: Sawssen
authors.initials: S
authors.lastname: Hajji
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, National School of Engineering of Sfax; University of Sfax, B.P. 1173, 3038 Sfax, Tunisia.
authors.forename: Olfa
authors.initials: O
authors.lastname: Ghorbel-Bellaaj
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, National School of Engineering of Sfax; University of Sfax, B.P. 1173, 3038 Sfax, Tunisia.
authors.forename: Islem
authors.initials: I
authors.lastname: Younes
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, National School of Engineering of Sfax; University of Sfax, B.P. 1173, 3038 Sfax, Tunisia.
authors.forename: Kemel
authors.initials: K
authors.lastname: Jellouli
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, National School of Engineering of Sfax; University of Sfax, B.P. 1173, 3038 Sfax, Tunisia.
authors.forename: Moncef
authors.initials: M
authors.lastname: Nasri
mesh_terms: D060105:Animal Shells / Q000737:chemistry*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D001407:Bacillus / Q000187:drug effects / Q000201:enzymology; D001426:Bacterial Proteins / Q000378:metabolism; D001713:Biphenyl Compounds / Q000037:antagonists & inhibitors; D003386:Brachyura / Q000737:chemistry*; D002686:Chitin / Q000302:isolation & purification*; D045424:Complex Mixtures / Q000737:chemistry / Q000494:pharmacology*; D052978:Disk Diffusion Antimicrobial Tests; D005285:Fermentation; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000254:growth & development; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000254:growth & development; D006868:Hydrolysis; D017665:Hydroxyl Radical / Q000037:antagonists & inhibitors; D010851:Picrates / Q000037:antagonists & inhibitors
chemical_list: D000900:Anti-Bacterial Agents; D000975:Antioxidants; D001426:Bacterial Proteins; D001713:Biphenyl Compounds; D045424:Complex Mixtures; D010851:Picrates; D002686:Chitin; D017665:Hydroxyl Radical; C004931:1,1-diphenyl-2-picrylhydrazyl; D005947:Glucose
keywords: Antioxidant and antimicrobial activities; Bacillus strains; Chitin; Crab waste; FCSs; Fermentation