Conditions for the partial removal of lipopolysaccharide (LPS) from Thiobacillusferrooxidans are described. Raising the pH of the solution containing the cells from pH 1.5 to pH 6.8 to 8.0 releases about 50% of the LPS without cell lysis. The release of LPS begins at pH 3.5, and it was not affected by EDTA concentration. Partial removal of LPS exposed higher amounts of a 40-kDa outer membrane protein in the bacteria, as detected by a dot immunoassay employing an antiserum against the T. ferrooxidans surface protein. This higher protein exposure and the reduced LPS content increased the hydrophobicity of the cell surface, as determined by an increased adhesion (50%) to hydrophobic sulfur prills and 14C-dodecanoic acid binding (2.5-fold) compared with control cells. In addition, adhesion of radioactively labeled microorganisms to a sulfide mineral was inhibited (40%) in the presence of previously added LPS. Our results suggest that not only LPS but also surface proteins probably play important roles in T. ferrooxidans adhesion to solid surfaces.
Heartwood aqueous extracts from Enterolobium cyclocarpum (Jacq.) Griseb. exhibited chronic toxic lethal effect against Incisitermes marginipennis (Latreille) with more than 60% mortality at a concentration of 56.63 mg. Feeding rate correlated positively with the mortality of termites. The termite hindgut cellulolytic activity, the symbiotic microorganism population in termite hindgut and fungal cellulase activity were not inhibited by the aqueous extract. Two major chemical groups were detected in aqueous extract by gas chromatography; they were monoterpenes (46.5%) and phenols (18.7%). Fifty seven constituents, including, D-limonene, terpineol and eugenol were identified; these terpenes have repellent activity against insects. These results suggest that essential oils from E. cyclocarpum contain a slow acting toxin with a dissuasive effect on termites.
Thirty six samples arising from hexane, dichloromethane, and methanol extracts from four medicinal Eupatorium species were screened against Gram positive and Gram negative resistant bacteria associated with nosocomial infections by disk diffusion method. The best antibacterial extracts were selected by correspondence analysis. The hexane extracts showed high inhibition against clinical isolated bacteria. The qualitative chemical analysis was realized in the best antibacterial hexane extracts. The main components identified were triterpenes and benzopyran compounds which of extensively had been reported their antibacterial activities. Our results showing that medicinal Eupatorium species studied in this work have metabolites secondary antibacterial particularly against antibiotic resistant strains, Klebsiella pneumoniae and Staphylococcus aureus and validate their uses in traditional medicine.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.