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Cross-sectional schematic depicting a typical mature biofilm. A layer of cells covers the substrate, and pillars supporting cell clusters encased in extracellular polysaccharide allow the formation of channels for convective and diffusive flow of nutrients through the film. Streamers allow maximal contact of biofilm cells with the bulk fluid and are common in Pseudomonas biofilms. (from http://www.erc.montana.edu/ CBEssentials-SW/research/Structure_function/ default.htm)
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Bacteria utilize small signaling molecules, or autoinducers, to regulate their gene expression in tandem by a process termed quorum sensing. The gene encoding the synthase for autoinducer-2 (AI-2), luxS, is conserved in dozens of diverse bacteria. Behaviors controlled by AI-2 include virulence, motility, toxin production, and biofilm formation. The...
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... 33: Effect of brominated furanone on biofilm growth in Listeria innocua normalized to the non-disturbed optical densities. The ratio of destained crystal violet optical densities at 595 nm in Figure 31 were divided by the optical densities in Figure 32. Figure 36: Effect of brominated furanone on biofilm growth in Bacillus cereus normalized to the non-disturbed optical densities. The ratio of destained crystal violet optical densities at 595 nm in Figure 34 were divided by the optical densities in Figure 35. ...
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... thickness of biofilms can range anywhere from a sub-monolayer of cells to hundreds of millimeters. A cross-sectional schematic of a typical mature biofilm is shown in Figure 1, however the structure of biofilms of individual species and in different environmental conditions can vary significantly. ...
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... little to no information existed on optimal conditions for biofilm formation in Listeria innocua and Bacillus cereus. A series of dilutions of different rich media, supplementation with glucose and yeast extract, and different temperatures were tested (Figures 9 and 10). For Listeria innocua, it was found that biofilm formation was greatest when grown at 23°C in BHI medium supplemented with 0.2% glucose. ...
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... of HPLC chromatograms obtained are shown in Figure 11. Additionally, each batch was tested for its ability to induce bioluminescence in Vibrio harveyi BB170. ...
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... effect of in vitro AI-2 on biofilm formation in E. coli was tested to verify that the 96 well format of the biofilm assay produced similar results to those obtained previously in this group using culture tubes (unpublished data). Results of independent experiments are shown for W3110, DH5α, and K-12 in Figure 12, and for W3110 and DH5α in Figure 13 (with improved controls and glucose supplementation). An AI-2 concentration- dependent increase in biofilm is observed for E. coli W3110 and E. coli K-12. ...
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... effect of in vitro AI-2 on biofilm formation in E. coli was tested to verify that the 96 well format of the biofilm assay produced similar results to those obtained previously in this group using culture tubes (unpublished data). Results of independent experiments are shown for W3110, DH5α, and K-12 in Figure 12, and for W3110 and DH5α in Figure 13 (with improved controls and glucose supplementation). An AI-2 concentration- dependent increase in biofilm is observed for E. coli W3110 and E. coli K-12. ...
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... an uncharacterized protein that stimulates the two-component motility regulatory system QseBC. 81 The effect of AI-2 on biofilm formation in Bacillus cereus is shown in Figure 14. ...
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... the genes encoding YrhA (an O-acetylserine thiol lyase) and YrhB (a possesses an Lsr-like system 52 , so it is possible that glucose represses lsr transcription, thereby delaying importation of AI-2 until glucose is depleted. As shown in Figure 14, biofilm growth in glucose-supplemented medium is very low after 23.5 hours but is markedly increased after 45.5 hours. AI-2 also appears to induce a slight growth inhibitory effect in B. cereus, independent from addition of adenine and homocysteine, as shown in Figure 15. ...
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... seen in Figure 21, SARH also had no statistically significant effect on biofilm formation in Listeria innocua. ...
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... addition of brominated furanone to Listeria innocua strongly quenches biofilm formation, with minimum biofilm evident with the addition of 50 µg/mL (Figure 31). At a concentration of 100 µg/mL furanone, biofilm formation in BHI medium increases over that seen with 50 µg/mL furanone, but is still decreased relative to the negative control. ...
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... is immediately apparent from Figure 32 that the addition of furanone also strongly quenches bulk growth in Listeria innocua. To determine whether biofilm growth was reduced relative to bulk growth, the ratio of optical densities in Figure 31 to Figure 32 is plotted in Figure 33. Figure 33: Effect of brominated furanone on biofilm growth in Listeria innocua normalized to the non-disturbed optical densities. The ratio of destained crystal violet optical densities at 595 nm in Figure 31 were divided by the optical densities in Figure 32. ...
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... determine whether biofilm growth was reduced relative to bulk growth, the ratio of optical densities in Figure 31 to Figure 32 is plotted in Figure 33. Figure 33: Effect of brominated furanone on biofilm growth in Listeria innocua normalized to the non-disturbed optical densities. The ratio of destained crystal violet optical densities at 595 nm in Figure 31 were divided by the optical densities in Figure 32. Error bars represent propagated standard deviations about the mean of six replicate wells. ...
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Biofouling is a major problem in operating reverse osmosis (RO) processes. Although biocides such as chlorine are commonly used to reduce biofouling, their strong oxidative activity and toxicity negatively affect the operation of RO processes. 6-gingerol analogs, structural derivatives of the main component of ginger, are quorum sensing (QS) inhibi...
Citations
... have been reported to inhibit quorum sensing in Listeria spp. through repression of peptide biosynthesis [49], inhibition of luxS by 8oxotetrahydrothalifendine [50] and S-anhydroribosyl-L-homocysteine [51], (5Z)-4-bromo-5-(bromomethylene)-3-butyl-2(5H)-furanone, a brominated furanone synthesized from Delisea pulchra [52]. The chemical structures of quorum sensing inhibitors as discussed above are presented in Fig. 2a. ...
There is an increasing trend in the food industry on the Listeria monocytogenes biofilm formation and inhibition. This is attributed to its easy survival on contact surfaces, resistance to disinfectants or antibiotics and growth under the stringent condition used for food processing and preservation thereby leading to food contamination products by direct or indirect exposure. Though, there is a lack of conclusive evidences about the mechanism of biofilm formation, in this review, the concept of biofilm formation and various chemical, physical, and green technology approaches to prevent or control the biofilm formed is discussed. State-of-the-art approaches ranging from the application of natural to synthetic molecules with high effectiveness and non-toxicity targeted at the different steps of biofilm formation could positively influence the biofilm inhibition in the future.
... 5'-methylthioadenosine nucleosidase (MTAN) inhibitors play dual roles as quorum quenchers in AI-2 and AHL biosynthesis (LaSarre and Federle, 2013). Halogenated furanoes, such as brominated furanoes derived from the red alga Delisea pulchra, have a direct role in inhibiting AI-2 quorum sensing (Lennen, 2007). Increasing the concentration of in vitroproduced AI-2 has a negative impact on biofilm density (Auger et al., 2006). ...
Immunity, virulence, biofilm formation, and survival in the host environment are regulated by the versatile nature of density dependent microbial cell signaling, also called quorum sensing (QS). The QS molecules can associate with host plant tissues and, at times, cause a change in its gene expression at the downstream level through inter-kingdom cross talking. Progress in controlling QS through fungicide/bactericide in pathogenic microscopic organisms has lead to a rise of antibiotic resistance pathogens. Here, we review the application of selective quorum quenching (QQ) endophytes to control phytopathogens that are shared by most, if not all, terrestrial plant species as well as aquatic plants. Allowing the plants to posses endophytic colonies through biotization will be an additional and a sustainable encompassing methodology resulting in attenuated virulence rather than killing the pathogens. Furthermore, the introduced endophytes could serve as a potential biofertilizer and bioprotection agent, which in turn increases the PAMP- triggered immunity and hormonal systemic acquired resistance (SAR) in plants through SA-JA-ET signaling systems. This paper discusses major challenges imposed by QS and QQ application in biotechnology.
... Different compounds have different elution times based upon their affinity with the stationary phase of chromatography column. In this case, the elution time for adenine is 4.8min, the elution time for SRH is 4.3 min, and the elution time for SAH is 8.4min [32] . By comparing the SAH peak area in a converted sample to that of the unconverted, it is possible to determine the amount of SAH remaining in the sample, and therefore the degree of enzymatic conversion. ...
ATP-binding cassette (ABC) transporters are one of the largest families of membrane proteins in prokaryotic organisms. Much is now understood about the structure of these transporters and many reviews have been written on that subject. In contrast, less has been written on the assembly of ABC transporter complexes and this will be a major focus of this book chapter. The complexes are formed from two cytoplasmic subunits that are highly conserved (in terms of their primary and three-dimensional structures) across the whole family. These ATP-binding subunits give rise to the name of the family. They must assemble with two transmembrane subunits that will typically form the permease component of the transporter. The transmembrane subunits have been found to be surprisingly diverse in structure when the whole family is examined, with seven distinct folds identified so far. Hence nucleotide-binding subunits appear to have been bolted on to a variety of transmembrane platforms during evolution, leading to a greater variety in function. Furthermore, many importers within the family utilise a further external substrate-binding component to trap scarce substrates and deliver them to the correct permease components. In this chapter, we will discuss whether assembly of the various ABC transporter subunits occurs with high fidelity within the crowded cellular environment and whether promiscuity in assembly of transmembrane and cytoplasmic components can occur. We also discuss the new AlphaFold protein structure prediction tool which predicts a new type of transmembrane domain fold within the ABC transporters that is associated with cation exporters of bacteria and plants.
