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Curr Microbiol (2011) 62:1017–1022
DOI 10.1007/s00284-010-9814-z

Antimicrobial Activity of Bacillus amyloliquefaciens LBM 5006
is Enhanced in the Presence of Escherichia coli
Lisianne Benitez • AnaPaula Correa
Daniel Daroit • Adriano Brandelli

Received: 22 September 2010 / Accepted: 2 November 2010 / Published online: 21 November 2010
Ó Springer Science+Business Media, LLC 2010Abstract Increased antimicrobial activity was observed
when Bacillus amyloliquefaciens LBM 5006 strain was
cultivated in the presence of thermally inactivated cells of
Escherichia coli, but not with Staphylococcus aureus,
Listeria monocytogenes, or Bacillus cereus. E. coli also
enhanced the antimicrobial activity when it was added to
the medium in the form of living cells or as cell debrisafter
cellular fractionation. No inducing activity was observed
with addition of cell-free supernatant of E. coli cultures,
suggesting that inducing factor is associated to the cells.
Polyacrylamide gel electrophoresis revealed that additional
peptide bands are secreted when B. amyloliquefaciens was
cultivated in the presence of cell debris of E. coli. These
results suggest that thepresence of intact or inactivated
E. coli enhanced the synthesis of antimicrobial peptides by
B. amyloliquefaciens LBM 5006.

L. Benitez
Bioquımica e Microbiologia, Universidade Federal do Rio
Grande do Sul, Porto Alegre, Brazil
A. Correa
Centro de Biotecnologia, Universidade Federal do Rio Grande
do Sul, Porto Alegre, Brazil
D. Daroit
Universidade Federal do Rio Grande do Sul,
PortoAlegre, Brazil
A. Brandelli (&)
Departamento de Ciencia de Alimentos, Universidade Federal do
Rio Grande do Sul, Porto Alegre, Brazil

Bacteria of the genus Bacillus can produce a large number
of antimicrobial peptides with different chemical structures, such as bacteriocins, bacteriocin-like substances
(BLS), and lipopeptides [13, 23]. Although most ofthese
substances are active against Gram-positive microorganisms, some of them have a wide range of activity including
Gram-negative bacteria and fungi [6, 22]. Considering their
role as defense peptides, there is evidence that cellular
signaling mechanisms are involved in the biosynthesis.
Also, the producer organisms are immune to their own
peptide, a property that is mediated by specificimmunity
proteins [4, 7].
Microorganisms use considerable energy in the development of antimicrobial mechanisms and synthesis of
defense peptides, but it is not yet clarified the role that
these compounds exert on the microbial communities. The
situations in which the biosynthesis is required are often
regulated by the shortage of nutrients in the growing
medium as occurs in sporulation, thesynthesis of extracellular enzymes and the development of genetic competence [19]. The antimicrobial peptides may play a
defensive role and prevent the invasion of other strains or
species into an occupied niche or limit the advance of
neighboring cells. The mediation of quorum-sensing systems is an additional role proposed for bacteriocins of
Gram-positive bacteria [15, 19]. The presence ofcertain
bacteria acts as an environmental signal to activate the
production of bacteriocin by Lactobacillus plantarum NC8
[11]. A quorum-sensing mechanism mediated by an
induction factor (PLNC8IF) appears to be involved in this
process. The phenomenon of induction in the production of
bacteriocins has been little investigated, but several studies
showing the interference of othermicroorganisms in the



L. Benitez et al.: Antimicrobial Activity of Bacillus amyloliquefaciens LBM 5006

synthesis of bacteriocins by lactic acid bacteria are reported
in the literature [5, 20, 21]. However, the effect of competing microorganisms in the activation of bacteriocin
synthesis by bacteria of the genus Bacillus has not been
reported to date.
Bacillus amyloliquefaciens LBM...
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