A. Delgado et al., Antimicrobial activity of L-plantarum, isolated from a traditional lactic acid fermentation of table olives, LAIT, 81(1-2), 2001, pp. 203-215
Lactobacillus plantarum strain LB17.2b, isolated from traditional table oli
ve fermentation has been shown to produce thermostable antibacterial protei
ns. At pH 6.5, the proteinaceous fraction obtained from culture supernatant
was active against Enterococcus faecalis and against natural competitors o
f L. plantarum from olive fermentation brines. Bioactivity was quantified a
gainst Weissella paramesenteroides DSM20288 using the critical dilution met
hod by a regression procedure. This bioactivity has been found to be growth
-associated indicating a primary metabolite kinetics. Ultrafiltration studi
es with supernatants from different fermentation times have been carried ou
t. A twofold increase in the activity of the retentate from the 30 kg.mol(-
1) cut-off membrane was observed, by comparison with the total activity app
lied to this membrane (culture supernatant). The addition of the filtrate t
o this retentate caused a marked drop in activity, most probably associated
with the presence of an inhibitor. These studies also demonstrated the pre
sence of another antibacterial proteinaceous compound showing a wider inhib
itory spectrum and produced during culture stationary phase. In the presenc
e of lactic acid (pH 3.7), these antimicrobial proteinaceous compounds have
been found to inhibit Gram-negative human pathogens, probably by a synergi
stic effect. At the present time one bacteriocin-like compound was isolated
, showing a molecular mass of approximately 50 kg.mol(-1). The presence of
another compound of different properties and with a molecular mass between
3 and 10 kg.mol(-1) was also detected.