Antibacterial activity of a polysaccharide produced from Chaetomium globosum CGMCC 6882.

In present work, a polysaccharide (GCP) was produced by Chaetomium globosum CGMCC 6882 and characterized. GCP was composed of arabinose, galactose, glucose, xylose, mannose and glucuronic acid in a molar ratio of 0.64: 2.58: 23.53: 0.90: 2.47: 0.27 with molecular weight of 8.093 × 104 Da and polydispersity (Mw/Mn) of 1.014. Antibacterial characteristics and mechanism of GCP against Escherichia coli and Staphlococcus aureus were investigated by analysis of inhibition zones, minimum inhibitory concentration (MIC), alkaline phosphatase and β-galactosidase activities, electrical conductivity and bacterial morphology. Results showed that the MIC of GCP against E. coli and S. aureus were 1.75 mg/mL and 0.67 mg/mL, respectively. Moreover, GCP exerted antibacterial activities by disrupting the inner membrane and increasing the cell permeability, but had no influences on cell wall. This work indicated that GCP could be explored as a promising antibacterial agent in food and pharmaceutical industries.