Abstract
Chemical analysis and toxic ty assay of Pasteurella piscicida lipopolysaccharide (LPS) preparations used for immunization of yellowtail (Seriola quinqueradiata) were performed. LPS fractions were obtained by the phenol-water (P-LPS) or phenol-chloroform-petroleum ether (PCP-LPS) methods followed by purification with Cetavlon or ultracentrifugation, respectively. P-LPS was composed of 0.87% protein, 24.0% sugar and 36.0% fatty acid. Whereas PCP-LPS of 0.34% protein, 18.0% sugar and 34.2% fatty acid. The monosaccharide of P-LPS and PCP-LPS was respectively : 30.6% and 16.5% hexose; 3.8% and 2.1% heptose; 2.2% and 3.6% pentose; 2.2% and 3.2% 6-deoxyhexose; 3.2% and 2.6% 2-keto-3-deoxyoctonate (KDO); and 2.8% and 2.4% hexosamine. The fatty acids were analyzed by gas-liquid chromatography (GLC) as their methyl esters. Their identities were confirmed by mass spectrometry. Those analyses showed that the principal constituents were : lauric acid, 3-hydroxy lauric acid, myristic acid and palmitic acid. The acute toxicity assay using mice injected i.p. showed that the P-LPS preparation was more toxic than PCP-LPS. The Limulus amoebocyte assay did not show differences between the two preparations.
