title: Size and pH effects of chitooligomers on antibacterial activity against Staphylococcus aureus.
abstract: The antimicrobial activity of chitooligomers (COSs) has attracted considerable interest but there are few reports on antibacterial activity of each individual COS. This study focuses on investigating the size and pH effects of COS on its antibacterial activity against Staphylococcus aureus. Minimum inhibitory concentrations (MICs) of five single COSs and five COS fractions with narrow degrees of polymerization (DP) were determined at different pH mediums. The results revealed that the antibacterial activity of COS required structural essential with a DP of at least 5 and the inhibitory effect increased with increasing DP. Lower pH value could enhance the antibacterial activity of COS. The COS with DP>12 showed a MIC value of 62.5mg/mL at pH 6.0, while the MIC value increased to 500 and 1000 mg/mL at pH 6.5 and 7.0, respectively. The cell membrane integrity assay and SEM suggested that the COS with high DP could cause bacteria clustering and further lysis of cell.
authors: Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
authors: Kecheng
authors: K
authors: Li
authors: Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
authors: Ronge
authors: R
authors: Xing
authors: Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
authors: Song
authors: S
authors: Liu
authors: Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
authors: Yukun
authors: Y
authors: Qin
authors: Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
authors: Huahua
authors: H
authors: Yu
authors: Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China. Electronic address: pcli@qdio.ac.cn.
authors: Pengcheng
authors: P
authors: Li
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests; D008970:Molecular Weight; D009844:Oligosaccharides / Q000737:chemistry* / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D009844:Oligosaccharides
keywords: Antibacterial activity; Chitooligomers; Size