Isolation, Characterization, Bioactivity, and Antioxidant Properties of Lipopolysaccharides of Marine Bacterium Idiomarina fontislapidosi BK07

Abstract

The lipopolysaccharide (LPS) of marine bacteria have aroused widespread attention due to their low virulence potential, non-toxicity, and nutritional and therapeutic benefits. Due to their unusual chemical compositions, these traits are best displayed in their natural sea environment. The LPS from a marine bacterium Idiomarina fontislapidosi was isolated, purified, and characterized. Gas Chromatography Mass Spectrometry (GCMS) analysis of isolated LPS described the prominent fatty acids were 3-hydroxy dodecanoic acid (C_{12:0 3OH}), 2-hydroxy dodecanoic acid (C_{12:0 2OH}), dodecanoic acid (C_12:0), decanoic acid (C_10:0), and iso-decanoic acid (C_10:0iso) together with hexadecanoic acid (C_16:0). The monosaccharide constituents of the LPS included mannose, followed by glucose, rhamnose, galactose and xylose. Sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) revealed LPS as the semi rough-type because of the presence of a smear near and few bands present far from the well. The LPS was also found to be non-toxic because it did not express limulus amoebocyte lysate (LAL) gelation activity. Bioactivities of the marine LPS describe that it could not exert inhibitory action on six tested bacteria, viz. Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Pseudomonas aeruginosa PA01 and two clinical strains, P. aeruginosa PAL and P. aeruginosa PAH. Isolated LPS manifested a unique property by showing strong (98%) antioxidant activity by scavenging 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals. In stress circumstances including temperature, salinity and light, the marine LPS may scavenge generated reactive oxygen species (ROS) to defend against oxidative damage. This is the first report on antioxidant activity for any LPS and characterization of LPS from I. fontislapidosi so far.