title: Optimized production of Serratia marcescens B742 mutants for preparing chitin from shrimp shells powders.
abstract: To improve the deproteinization (DP) efficacy of shrimp shell powders (SSP) for preparing chitin, Serratia marcescens B742 mutants were prepared using 2% diethyl sulfate (DES), UV-irradiation, and/or microwave heating treatments. Both single-stage and multi-stage mutations were investigated for optimizing S. marcescens B742 mutation conditions. Under the optimized mutation conditions (2% DES treatment for 30min plus successive 20min UV-irradiation), the protease and chitosanase activity produced by mutant S. marcescens B742 was 240.15 and 170.6mU/mL, respectively, as compared with 212.58±1.51 and 83.75±6.51mU/mL, respectively, by wild S. marcescens B742. DP efficacy of SSP by mutant S. marcescens B742 reached 91.4±4.6% after 3d of submerged fermentation instead of 83.4±4.7% from the wild S. marcescens B742 after 4d of submerged fermentation. Molecular mass of chitosanase and protease was 41.20 and 47.10kDa, respectively, and both enzymes were verified by mass spectrometry analysis. The chitosanase from both wild and mutant S. marcescens B742 was activated by sodium dodecyl sulfate (SDS), Tween 20, Tween 40, and Triton-100, and the protease and chitosanase were strongly inhibited by ethylenediaminetetraacetic acid (EDTA). These results suggested that S. marcescens B742 mutants can be used in the biological production of chitin through deproteinization of SSP.
authors.affiliation: School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, PR China.
authors.forename: Hongcai
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, PR China.
authors.forename: Jiyang
authors.initials: J
authors.lastname: Fang
authors.affiliation: School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, PR China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Deng
authors.affiliation: School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, PR China; Department of Food Science and Technology, Oregon State University, Corvallis, OR 97331-6602, USA. Electronic address: yanyun.zhao@oregonstate.edu.
authors.forename: Yanyun
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D060105:Animal Shells / Q000737:chemistry*; D000818:Animals; D002686:Chitin / Q000378:metabolism*; D003445:Crustacea / Q000737:chemistry*; D004795:Enzyme Stability / Q000187:drug effects; D005285:Fermentation / Q000187:drug effects; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D009154:Mutation; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011208:Powders; D012706:Serratia marcescens / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D013501:Surface-Active Agents / Q000494:pharmacology; D013696:Temperature
chemical_list: D011208:Powders; D013501:Surface-Active Agents; D002686:Chitin; D006026:Glycoside Hydrolases; C019868:chitosanase; D010447:Peptide Hydrolases
keywords: Chitin; Mutation; Protease; Serratia marcescens B742