Thesis-1984-Stocker.pdf (2.14 MB)
Studies of the action of venom and venom constituents on Escherichia coli
thesisposted on 2017-07-27, 08:35 authored by Jane F. Stocker
Studies of the action of venom and venom constituents on Escherichia coli. The antibacterial activity of honeybee venom (Apis mellifera) , three snake venoms (Naja naja sputatrix, Vipera russellii and Crotalus adamanteus) and the polypeptide melittin (a component of honeybee venom) was investigated against the gram-negative organism Escherichia coli. Minimum inhibitory concentration (MIC) values were determined and action against proliferating and non-proliferating cells was in the order: Apis mellifera venom > melittin > Naja naja sputatrix > Vipera russellii venom > Crotalus adamanteus venom. Cell lysis was determined by absorbancy changes and was caused by the more active venoms (Apis mellifera and Naja naja sputatrix) and melittin. Alteration of the permeability of the cell envelope of Escherichia coli cells harvested in mid-log phase was followed principally by measuring β-galactosidase release from cells. Venom activity decreased in the same order as MIC above. Phospholipases A₂ from Apis mellifera and Naja naja sputatrix venoms, melittin and polymixin B (polypeptide antibiotic) increased β-galactosidase release. No synergism between the phospholipases A₂ and melittin was seen under the conditions employed. Separation of Apis mellifera and Naja naja sputatrix venoms was carried out by gel filtration and electrophoresis. The action of venom components implies that the antibacterial activity of whole venom is not totally accounted for by that of the venom polypeptide toxins melittin or direct lytic factor (DLF). That the antibacterial activity of Apis mellifera and Naja naja sputatrix venoms and melittin is due at least in part to membrane disruption is supported by electron microscopy studies.
Publisher© J. F. Stocker
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NotesA Masters Thesis. Submitted in partial fulfilment of the requirements for the award of Master of Philosophy of Loughborough University.