Optimization of chitin yield from shrimp shell waste by Bacillus subtilis and impact of gamma irradiation on production of low molecular weight chitosan.
Chitin and chitosan have been produced from the exoskeletons of crustacean shells such as shrimps. In this study, seventy bacterial isolates, isolated from soil, were tested for proteolytic enzymes production. The most efficient one, identified as Bacillus subtilis, was employed to extract chitin from shrimp shell waste (SSW). Following one-variable-at-a-time approach, the relevant factors affecting deproteinization (DP) and demineralization (DM) were sucrose concentration (10%, w/v), SSW concentration (5%, w/v), inoculum size (15%, v/v), and fermentation time (6days). These factors were optimized subsequently using Box-Behnken design and response surface methodology. Maximum DP (97.65%) and DM (82.94%) were predicted at sucrose concentration (5%), SSW concentration (12.5%), inoculum size (10%, containing 35×10(8) CFU/mL), and fermentation time (7days). The predicted optimum values were verified by additional experiment. The values of DP (96.0%) and DM (82.1%) obtained experimentally correlated to the predicted values which justify the authenticity of optimum points. Overall 1.3-fold increase in DP% and DM% was obtained compared with 75.27% and 63.50%, respectively, before optimization. Gamma-irradiation (35kGy) reduced deacetylation time of irradiated chitin by 4.5-fold compared with non-irradiated chitin. The molecular weight of chitosan was decreased from 1.9×10(6) (non-irradiated) to 3.7×10(4)g/mol (at 35kGy).
Department of Agricultural Microbiology, Faculty of Agriculture, Ain Shams University, Egypt.
Rawia F
RF
Gamal
Department of Agricultural Microbiology, Faculty of Agriculture, Ain Shams University, Egypt.
Tarek S
TS
El-Tayeb
Department of Radiation Microbiology, National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority, Cairo, Egypt.
Enas I
EI
Raffat
Department of Radiation Microbiology, National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority, Cairo, Egypt.
Haytham M M
HM
Ibrahim
Department of Radiation Microbiology, National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority, Cairo, Egypt. Electronic address: monembash@hotmail.com.
A S
AS
Bashandy
D000107:Acetylation; D060105:Animal Shells / Q000737:chemistry*; D000818:Animals; D001412:Bacillus subtilis / Q000378:metabolism; D002686:Chitin / Q000096:biosynthesis* / Q000528:radiation effects*; D033364:Decapoda / Q000737:chemistry*; D004307:Dose-Response Relationship, Radiation; D005285:Fermentation / Q000187:drug effects; D005720:Gamma Rays; D008970:Molecular Weight; D010447:Peptide Hydrolases / Q000302:isolation & purification; D015203:Reproducibility of Results; D013395:Sucrose / Q000494:pharmacology; D013997:Time Factors; D014866:Waste Products
D014866:Waste Products; D002686:Chitin; D013395:Sucrose; D010447:Peptide Hydrolases
Bacillus subtilis; Chitin; Chitosan; Shrimp shell waste; γ-Radiation