359
quenching compounds, namely, AHL-acylase and AHL-lactonase have been found
to be of great potential to control biofouling via disrupting the quorum sensing process in Aeromonas hydrophila mostly involved in biofilm formation in waste water
treatment plants (Lade et al. 2014).
(d) Quorum Quenching and multidrug resistance
It has also been envisioned that some of the compounds from plant and microbes
can control the AHL-mediated biofilm formation without affecting bacterial growth
thus reducing the virulence and risk of multidrug resistance (Lade et al. 2014).
(e) Quorum Quenching and biological control
Quorum quenching can be used as an alternative approach to regulate pathogenicity. The strategy involves direct introduction of a gene coding for AHL Synthase
to the plant cells or the use of AHL disrupting bacteria to protect plants and heterologous expression of the genes encoding AHL-degrading enzymes in pathogenic
cells or plant tissue. Thus, bacteria misapprehend the size of the population and this
leads to the production of virulence factors before the pathogen population is significant enough to continue infection (Anderson et al. 2006; Moghaddam 2014).
Various studies have shown that the application of bacterial cells having the ability
to produce AHL-degrading enzymes can be employed as natural control agents for
controlling bacterial diseases in plants. Dong et al. (2007) have reported first such
an example in transgenic plants Solanum tuberosum (potato) and Nicotiana tabacum (tobacco) expressing the gene encoding AiiA lactonase showing strong resistance against Pectobacterium cartovorum infection. Heterologous expression of
AiiA gene encoding the AiiA lactonase from Bacillus sp. in plant pathogen cells
Pectobacterium cartovorum, Burkholderia thilandensis, and Erwinia amylovorai
showed disease symptom development. Hence, the quorum sensing inhibitors
together with AHL-degrading enzymes can be applied successfully to disrupt bacterial quorum sensing and to reduce bacterial colonization (Dong et al. 2007;
Moghaddam 2014).
(f) Quorum Quenching and immunotherapy
The process that how quorum sensing inhibitors can be used as defense molecules via immuno-pharmacotherapeutic approach for the attenuation of AHLdependent quorum sensing in the human pathogen Pseudomonas aeruginosa was
first reported by Kaufmann and group (Kaufmann et al. 2006, 2008). 3-oxo-C 12 -
HSL does not help in regulating the expression of virulence factors but it also plays
a pivotal role in pathogenesis via exerting cytotoxicity on host cells. A similar
approach was reported in Staphylococcus aureus by Park et al. (2007). Thus, these
findings provide a strong basis for further research in this area to develop immunotherapy to treat bacterial infections in those cases where quorum sensing controls
the expression of virulence factors.
14 Quorum Quenching Compounds from Natural Sources
quenching compounds, namely, AHL-acylase and AHL-lactonase have been found
to be of great potential to control biofouling via disrupting the quorum sensing process in Aeromonas hydrophila mostly involved in biofilm formation in waste water
treatment plants (Lade et al. 2014).
(d) Quorum Quenching and multidrug resistance
It has also been envisioned that some of the compounds from plant and microbes
can control the AHL-mediated biofilm formation without affecting bacterial growth
thus reducing the virulence and risk of multidrug resistance (Lade et al. 2014).
(e) Quorum Quenching and biological control
Quorum quenching can be used as an alternative approach to regulate pathogenicity. The strategy involves direct introduction of a gene coding for AHL Synthase
to the plant cells or the use of AHL disrupting bacteria to protect plants and heterologous expression of the genes encoding AHL-degrading enzymes in pathogenic
cells or plant tissue. Thus, bacteria misapprehend the size of the population and this
leads to the production of virulence factors before the pathogen population is significant enough to continue infection (Anderson et al. 2006; Moghaddam 2014).
Various studies have shown that the application of bacterial cells having the ability
to produce AHL-degrading enzymes can be employed as natural control agents for
controlling bacterial diseases in plants. Dong et al. (2007) have reported first such
an example in transgenic plants Solanum tuberosum (potato) and Nicotiana tabacum (tobacco) expressing the gene encoding AiiA lactonase showing strong resistance against Pectobacterium cartovorum infection. Heterologous expression of
AiiA gene encoding the AiiA lactonase from Bacillus sp. in plant pathogen cells
Pectobacterium cartovorum, Burkholderia thilandensis, and Erwinia amylovorai
showed disease symptom development. Hence, the quorum sensing inhibitors
together with AHL-degrading enzymes can be applied successfully to disrupt bacterial quorum sensing and to reduce bacterial colonization (Dong et al. 2007;
Moghaddam 2014).
(f) Quorum Quenching and immunotherapy
The process that how quorum sensing inhibitors can be used as defense molecules via immuno-pharmacotherapeutic approach for the attenuation of AHLdependent quorum sensing in the human pathogen Pseudomonas aeruginosa was
first reported by Kaufmann and group (Kaufmann et al. 2006, 2008). 3-oxo-C 12 -
HSL does not help in regulating the expression of virulence factors but it also plays
a pivotal role in pathogenesis via exerting cytotoxicity on host cells. A similar
approach was reported in Staphylococcus aureus by Park et al. (2007). Thus, these
findings provide a strong basis for further research in this area to develop immunotherapy to treat bacterial infections in those cases where quorum sensing controls
the expression of virulence factors.
14 Quorum Quenching Compounds from Natural Sources