Antibiofilm Strategies in the Food Industry - Antibiofilm Agents: From Diagnosis to Treatment and Prevention - page 364

developed in order to target synthesis of the cell signaling molecules themselves or
to block these signaling systems (Bai and Rai 2011 ).
QS systems appear to be involved in all phases of biofilm formation. They
regulate population density and the metabolic activity within the mature biofilm
to fit the nutritional demands and resources available. Furthermore, bacteria within
biofilms have markedly different transcriptional programs from planktonic bacteria
of the same strain (Asad and Opal 2008 ).
The relation between QS and biofilm formation in food-related bacteria has been
observed by several authors. However, according to Bai and Rai ( 2011 ), though
signaling molecules have been detected in biofilms, their precise role in the
different stages of biofilm formation is still not clear.
Kerekes and coauthors ( 2013 ) investigated the effect of clary sage, juniper,
lemon, and marjoram essential oils and their major components on the formation
of bacterial and yeast biofilms and on the inhibition of AHL mediated QS and
verified that the compounds tested seemed to be good candidates for prevention of
biofilm formation and inhibition of the AHL-mediated QS mechanism.
Furanones are one of the most studied QS inhibitors and it was demonstrated that
they were able to control multicellular behavior induced by autoinducer-1
(Manefield et al. 2002 ) and autoinducer-2 (Ren et al. 2004 ) in Gram-negative
microorganisms.
5.9 Bacteriophages
Bacteriophages (phages) are viruses that infect bacteria and can be found in the
same biosphere niches as their bacterial hosts (Kutter and Sulakvelidze 2005 ). They
were originally found by Harkin in 1896 and were applied in the cure of microbial
infections previous to antibiotic discovery. The application of phages to control
biofilms can be a practicable, natural, harmless, and greatly specific way to deal
with numerous microorganisms implicated in biofilm formation (Kudva
et al. 1999 ). In fact, phages and their endolysins have already been used to stop
biofilm development by L. monocytogenes and E. coli (Gaeng et al. 2009 ; Sharma
et al. 2005 ). Accordingly, a L. monocytogenes phage (ATCC 23074-B1) was
effectively used for biofilm eradication (Hibma et al. 1997 ), and a synergistic effect
of an alkaline disinfectant and a phage has been described for the eradication of
E. coli O157:H7 biofilms grown on stainless steel (Sharma et al. 2005 ). Moreover,
Lu and Collins ( 2007 ) produced a phage that expresses a biofilm-degrading
enzyme, which attacked both biofilm bacteria and matrix, leading to more than
99.9 % elimination of the biofilm cells.
A study conducted by Sillankorva and coworkers ( 2008 ) showed that the phage
phiIBB-PF7A can be an outstanding natural agent regarding its ability to lyse
P. fluorescens biofilm cells in a very short period of time. This same phage was
also applied to control a P. fluorescens and Staphylococcus lentus mixed biofilm
and led to a remarkable decline in the attached bacterial cells ( P. fluorescens ).