We here describe the isolation of a novel exopolysaccharide from Acinetobacter rhizosphaerae, named ArEPS. The structure of ArEPS was characterized by analysis of the monosaccharide composition, molecular weight, infrared spectrum, methylation, and nuclear magnetic resonance spectrum. ArEPS was found to be an acidic heteropolysaccharide composed of glucose, galactose, galacturonic acid, glucuronic acid, mannose, and glucosamine; the molecular weight was 1533 kDa. Structural analysis showed that the main-chain structure of ArEPS predominantly comprised 1,3,6-β-Glcp, 1,3,4-α-Galp, 1,2-β-Glcp, 1,4-β-GlcpA, 1,4-β-GalpA, and the side-chain structure comprised 1,6-β-Glcp, 1,3-β-Galp, 1-α-Glcp, 1-β-Galp, 1-α-Manp, 1,4,6-α-Glcp, 1,2,4-β-Glcp, 1,2,3-β-Glcp, and 1,3-β-GlcpN. ArEPS significantly enhanced the tolerance of rice seedlings to salt stress. Specifically, plant height, fresh weight, chlorophyll content, and the K+/Na+ ratio increased by 51 %, 63 %, 29 %, and 162 %, respectively, and the malondialdehyde content was reduced by 45 % after treatment with 100 mg/kg ArEPS compared to treatment with 100 mM NaCl. Finally, based on the quadratic regression between fresh weight and ArEPS addition, the optimal ArEPS addition level was estimated to be 135.12 mg/kg. These results indicate the prospects of ArEPS application in agriculture.
exopolysaccharides, Structural characterization, salt stress alleviation
NCBI PubMed ID: 38042318Publication DOI: 10.1016/j.ijbiomac.2023.128438Journal NLM ID: 7909578Publisher: Butterworth-Heinemann
Correspondence: F. Sha
; L. Sun
Institutions: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China, Suzhou Cornigs Polyols CO., LTD., Suzhou 215000, China, Westa College, Southwest University, Chongqing 400715, China, School of Chemical Biology & Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China
Methods: 13C NMR, 1H NMR, NMR-2D, GC-MS, FTIR, composition analysis, HPLC, statistical analysis, salt stress, HPGFC-MALLS-RI
Found