Affiliation:
1. Institute of Microbiology, Federal Dairy Research Center, D-2300 Kiel 1, Germany
Abstract
A survey was made on the bacteriocin-producing potential of lactic streptococci. Bacteriocin-like activities were isolated and partially purified from about 5% of the 280 strains investigated. The frequency of production varied from about 1% in
Streptococcus lactis
subsp.
diacetylactis
to 9 and 7.5% in
S. lactis
and
Streptococcus cremoris
, respectively. Eight strains of
S. cremoris
produced bacteriocins which, on the basis of heat stability at different pH values and inhibitory spectrum, could be divided into four types. From 54
S. lactis
strains, 5 strains produced inhibitory substances, namely, three nisin-like antibiotics and two different bacteriocins. Only 1 of 93
S. lactis
subsp.
diacetylactis
strains produced a bacteriocin which was very similar to bacteriocins of type I in
S. cremoris
. All of the bacteriocins that were partially purified by ammonium sulfate precipitation showed very limited inhibitory spectra. Most of the lactic streptococci and a few members of the genera
Clostridium, Leuconostoc
, and
Pediococcus
were inhibited. None of the bacteriocins acted on gram-negative bacteria. The bacteriocinogenic strains were also characterized on the basis of plasmid content. All strains possessed between one and nine plasmids ranging from 1 to 50 megadaltons.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology