Mossie, Godwin Mxolisi Kevin.
Characterization and mode of action of a bacteriocin produced by a Bacteroides Fragilis strain.
Degree: MS, Faculty of Science, Biochemistry, Microbiology and Biotechnology, 1980, Rhodes University
Bacteroides fragilis strain Bf-1 produces an extracellular bacteriocin at the beginning of the stationary growth phase. Production is not inducible by either ultraviolet light or mitomycin C. The low molecular weight bacteriocin (MW estimates of 13 500 and 18 800 obtained from Sephadex G-100 chromatography and SDS-PAGE electrophoresis respecively) is stable
between pH 7 - 9 and is inactivated on incubation with trypsin and pronase. An unusual feature of the Bf-1 bacteriocin is its apparent biphasic temperature stability: while the majority of the activity (97%) is destroyed by heating at 60ºC (t [subscript] 1/2 = 2.5 min at 60ºC), a small proportion (3%) is stable even after autoclaving at 121ºC for 15 min. The killing of sensitive cells occurs in 2 stages and the killing action is reversed by incubation with trypsin. The transition from stage I to stage II is dependent on the temperature of incubation and the growth state of sensitive cells. 2,4-Dinitrophenol prevents this transition. The Bf-1 bacteriocin has an unusual mode of action. It specifically inhibits RNA synthesis whilst having no effect on protein or DNA synthesis. No effect on intracellular ATP levels were observed. The heat-stable (3%) fraction had a similar biochemical effect. In vitro studies involving RNA polymerase indicated that the bacteriocin and the antibiotic rifampicin have similar effects on RNA synthesis. The bacteriocinogenic strain (Bf-1) is insensitive to its own bacteriocin both in vivo and in vitro, although this immunity is overcome in vitro by the addition of higher concentrations of the Bf-1 bacteriocin. The bacteriocinogenic strain (Bf-1) harbors a cryptic plasmid (or plasmids) which on a neutral sucrose gradient, sediments faster than the Col E1 marker plasmid DNA. Attempts to cure this strain of its bacteriocinogenic phenotype were unsuccessful.
Advisors/Committee Members: Woods, David R, Robb, Frank T.
Subjects/Keywords: Bacteroides; Anaerobic bacteria; Trypsin; Dinitrophenol; Proteins – Synthesis
to Zotero / EndNote / Reference
APA (6th Edition):
Mossie, G. M. K. (1980). Characterization and mode of action of a bacteriocin produced by a Bacteroides Fragilis strain. (Masters Thesis). Rhodes University. Retrieved from http://hdl.handle.net/10962/d1013543
Chicago Manual of Style (16th Edition):
Mossie, Godwin Mxolisi Kevin. “Characterization and mode of action of a bacteriocin produced by a Bacteroides Fragilis strain.” 1980. Masters Thesis, Rhodes University. Accessed April 13, 2021.
MLA Handbook (7th Edition):
Mossie, Godwin Mxolisi Kevin. “Characterization and mode of action of a bacteriocin produced by a Bacteroides Fragilis strain.” 1980. Web. 13 Apr 2021.
Mossie GMK. Characterization and mode of action of a bacteriocin produced by a Bacteroides Fragilis strain. [Internet] [Masters thesis]. Rhodes University; 1980. [cited 2021 Apr 13].
Available from: http://hdl.handle.net/10962/d1013543.
Council of Science Editors:
Mossie GMK. Characterization and mode of action of a bacteriocin produced by a Bacteroides Fragilis strain. [Masters Thesis]. Rhodes University; 1980. Available from: http://hdl.handle.net/10962/d1013543