2. INTRODUCTION
-Bacteriocins are bactericidal antibiotic like
substances.
-In nature it is protein which produced by many
bacteria.
-It inhibits or kills the growth of other kinds of
bacteria.
-It reduces the growth of bacterial strains that are
similar or closely associated.
-It is actually a proteinaceous toxin that is created
as a tiny molecule by bacteria.
-The toxin is regarded to be an antibiotic of
narrow spectrum and it is produced by a wide
array of bacteria.
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3. This toxin was first discovered in 1925 by Mr. A.
Gratia. He was looking for methods to destroy
bacteria. The search lead him to the discovery
of Bacteriocin as well as the finding of
bacteriophage and the developing of antibiotic.
Colicins fromThe first bacteriocins obtained is
E. Coli bacteria.
Since Colicin like substances are produced by
several other bacteria also, the generic
History
4. name bacteriocin was proposed by Jacob
(1952) .
Bacteriocins are given specific names based
on the bacterial species of origin, for example
:-
Colicins - E. coli
Pyocins - P.aeruginosa
Diphthericins - C.diphtheriae
5. The structure of this toxin usually
resembles the shape of a protein or
peptide. It consists of amino acid chains
of different size.
Bacteriocin Structure
6. 1-Bacteriocin that produce by G ve- bacteria:-
Such as E.Coli that produce Colicin and
Pseudomonase that produce Pyocin.
2-Bacteriocin that produce by G ve+ bacreria:-
Such as Lactic acid Bacteria ( Lactococcus) that
produceNisin and use it in food products and
preservations.
TYPE OF BACTERIOCIN:-
7. Two common mechanisms of action of
bacteriocins are :-
(i) Degradation of bacterial cell membranes by
producing pores in the membrane .
(ii) Degradation of bacterial DNA by DNAs.
Mechanisms Of Action
8. -Produce by non-pathogenic bacteria kills
other pathogenic bacteria(Normal flora vs.
Pathogens).
-Bacteriocins have also been suggested for
certain cancer treatment.
-Used for food preservation in food industry
(eg. Nisin) produced by Lactococcus lactis
is active against many food spoiling
bacteria.
-Used for bacteriocin typing of clinical
Importance
9. The medical importance of bacteriocins is that they
may be useful in :-
(1) Treating infections caused by antibiotic-resistant
bacteria.
(2) Nitrogen fixation enzymes in Rhizobium in the
root nodules of legumes.
(3) Tumors caused by Agrobacterium in plants.
(4) Several antibiotics produced by Streptomyces.
(5) A variety of degradative enzymes that are
produced by Pseudomonas and are capable of
cleaning up environmental hazards such as oil spills
and toxic chemical Waste site.
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-:Medical Importance
