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Purification and Characterization of two bacteriocins from Streptococcus faecium
Journal of General Microbiology
|May 1, 1975
Summary
This study identifies two bacteriocins, enterocin EIA and EIB, from Streptococcus faecium. Enterocin EIA is small, soluble, and heat-resistant, while EIB is larger and less thermostable, with distinct purification methods and activities against specific bacteria.
Area of Science:
- Microbiology
- Bacteriology
- Protein Chemistry
Background:
- Bacteriocins are ribosomally synthesized antimicrobial peptides produced by bacteria.
- Streptococcus faecium produces bacteriocins that exhibit antimicrobial activity against other bacteria.
- Understanding the properties and purification of bacteriocins is crucial for their potential applications.
Purpose of the Study:
- To isolate and characterize two distinct bacteriocins produced by Streptococcus faecium strain EI.
- To determine the purification strategies and biochemical properties of each bacteriocin.
- To investigate the spectrum of antimicrobial activity of the purified bacteriocins.
Main Methods:
- Bacteriocin purification involved ammonium sulfate fractionation, gel filtration (Sephadex G-75), and DEAE-cellulose chromatography for enterocin EIA.
- Enterocin EIB purification utilized differential centrifugation, Sepharose 4B chromatography, and density gradient ultracentrifugation.
- Characterization included molecular weight estimation, thermostability assays, and enzymatic/DNase treatment.
Main Results:
- Two bacteriocins, enterocin EIA and EIB, were identified in Streptococcus faecium EI.
- Enterocin EIA (approx. 10 kDa) was the predominant soluble bacteriocin, heat-resistant and trypsin-sensitive.
- Enterocin EIB (particle weight >4x10^6 Da) was released upon bacterial lysis, less thermostable, and insensitive to proteases and DNase.
- Antimicrobial activity was observed against specific strains of enterococci, Streptococcus salivarius, and Listeria monocytogenes.
Conclusions:
- Streptococcus faecium strain EI produces at least two bacteriocins with differing physicochemical properties and modes of action.
- Enterocin EIA and EIB represent distinct antimicrobial agents with potential for targeted bacterial inhibition.
- The differential characteristics of these bacteriocins highlight the complexity of bacteriocin production in enterococci.