Theresults describe the effectiveness of extracellular polymericsubstances (EPS) on increasing the biofilm formation byL.monocytogenesonthe spinach leaves and waxy surfaces.
Figure1: The Effectiveness of EPS Synthesized by L.monocytogenes theDegree of L.monocytogenes BiofilmFormation on Spinach Leaves
TheEPS that was extracted from L.monocytogenes planktoniccells.EPSshowed the ability to enhance the degree of biofilm formation on thespinach leaves in a 24-well plate. Refer to Figure 1. The extent ofbiofilm formation was compared between the treatment leaves (STDEV =13.103 and 2.714 in 24 and 6 hours period respectively) and theleaves with EPS (STDEV = 9.793 and 5.852 in 24 and 6 hour periodrespectively).
Figure2: The Effectiveness of L.monocytogenesEPSon Increasing the L.monocytogenes biofilmon Wax Surface
TheEPS extracted from L.monocytogenes planktoniccells showed that it has the ability to influence large biofilmformation by the L.monocytogenes cells. The wax, also referred to as docosonal was used as a model of plantwax during the study. The EPS together with wax demonstrated thegreatest effectiveness for the formation of biofilms.
Inthis study, the combination resulted in an average optical density of2.789 (STDEV = 0.2657) after a 6-hour period and an optical densityof 6.1077 (STDEV = 1.6219) after 24 hours. The optical density hadincreased by about 219% after 18 hours (6h to 24h) relative to theinitial 0.789. EPS has a significant effect in increasing theoptical density of the L.monocytogenes generatedbiofilm. Refer to Figure 1 and 2. In Figure 1 the presence of EPSdemonstrated to have increased the optical density of the biofilm.Figure 1 and 2 shows that the thickness and optical density of L.monocytogenes increaseswith time. It implies that as the time goes by the drug, which areinhibited by biofilms, progressively becomes less effective as timegoes by.
L.monocytogenes synthesizesand embed itself in EPS containing biofilm. The EPS molecules areresponsible for adhesion to surfaces. The adhesive properties,associated with L.monocytogenes, enablethe pathogens to attach itself successfully to almost all surfaces(Colargiorgi, etal.,2016). The substance allows the planktonic L.monocytogenes toadhere and thrive on the solid surfaces of food processingindustries. The biofilms express hydrophobic properties.Hydrophobicity refers the ability of a molecule to repel polarsubstances, especially water (Habimana, etal., 2009).The pathogen can even thrive at refrigeration temperatures (Tomiči,etal., 2016).
Thepathogen is often present in ready-to-eat and raw food products suchas milk, flour and cheese. L.monocytogenes contaminationof food products tend to occur at the post-processing phase. Thepathogen can thrive in low temperature conditions (<-1.5°C) andenvironments in reduced moisture content. The biofilm protects themicrobe from harsh temperature and low-moisture content. The pathogencan be isolated from surfaces after routine cleaning and disinfectionprocedures. The biofilm imparts the pathogen with an incrediblelevel of resistance towards most detergents and disinfectants. Thebiofilm formation capability depends on provided conditions. Forinstance, incubation of the L.monocytogenes culturesat low temperatures results in reduced biofilm formation capability.The type of the applied culturing media and the differences in theconcentrations of nutritive substances is associated with a widevariation in the thickness and composition of the synthesizedbiofilms (Tomiči, etal., 2016).
TheL.monocytogenes infectionsare associated with generation of severe diseases, high hospitaladmissions, and contribute to high mortality rate. The bacterium cancolonize almost all abiotic surfaces. Once L.monocytogenes attachto abiotic solid surfaces and synthesize biofilm, it tends to becomeincreasingly resistant to cleaning and disinfection, treatment. L.monocytogenes individualcells may detach from the initial colony formations and establishother similar microbial colonies elsewhere (Tomiči, etal., 2016).
Colargiorgi,A., Ciccio, P., Zanardi, E., Ghidini, S., & Lanieri, A. (2016). Alook inside the Listeriamonocytogenes biofilmsextracellular matrix. Microorganisms,4(3),22. doi: 10.3390/microorganisms4030022.
Habimana,O., Meyrand, M., Meylheuc, T., Kalakauskas, S., & Briandet, R.(2009). Genetic features of resident biofilms determine attachment ofListeriamonocytogenes. Appl. Environ. Microbiol., 75(24),7814-7821.
Tomiči,R.M., Čabarkapa, I.S., Vukmirović, D.M., Lević, J.D., &Tomičić, Z.M. (2016). Influence of growth conditions on biofilmformation of Listeriamonocytogenes.Journalof the Institute of Food Technology in Novi Sad, 43(1),19-24.