Sameer K.Bhagwat Research Scholar, M.TECH(Dairy Technology) ICAR-National Dairy Research Institute,Karnal(Haryana) 132001.

1. 1

2. Dairy Technology Division,
ICAR - NDRI , Karnal
credit
Seminar on
QUORUM SENSING IN CONTEXT OF DAIRY AND
FOOD INDUSTRY
PRESENTED BY
SAMEER K. BHAGWAT
M.Tech. (1st year)
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3. INTRODUCTION
HISTORY
PRINCIPLE OF MECHANISM
QUORUM SENSING MEDIATED PHENOMENONS
INHIBITION
CONCLUSION AND FUTURE PERSPECTIVES
CONTENTS
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4. • ‘Quorum’ is the Latin word
• Means the minimum number of members of an assembly or society that
must be present at any of its meetings to make the proceedings of that
meeting valid
WHAT IS QUORUM SENSING(QS)??
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5.  Regulatory process:- To ensure the sufficient cell density before a
specific gene product is made
 Cell–cell communication by unicellular microorganisms to co-ordinate
their activitiesand allows them to function as multi-cellular systems
 Led to “Sociomicrobiology”
(Parsek and Greenberg, 2005)
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6. HISTORY
First described
 By Nealson in 1970
 Vibrio fischeri
 Bioluminescent bacterium
 Symbiont in specialized light organs of the squid Euprymna scolopes and fish
Monocentris japonicas (Miller and Bassler, 2001)
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7. BASICS ABOUT QUORUM SENSING
 Bacterial showing quorum sensing requires two things:-
1. Signalling molecules called autoinducers or pheromones
1. A receptors that can specifically detect the signalling molecules
Bacterium
autoinducer
Receptor
autoinducer
Activates group
Behaviour genes
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(Gobbettiet al., 2007)
o e.g. Acyl-Homoserine Lactone (AHL)

8. MECHANISM OF BIOLUMINESCENCE
(March and Bentley, 2004)
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9. CELL DENSITY AND QUORUM SENSING
Cell
Density
Time
(https://www.google.co.in/cell+density+and+qourum+sensing , accessed on 17th April 2018)
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10. • Cell-to-cell signaling system: grouped into 4 main categories
• Autoinducer-1 (AI-1)
Gram negative cells
• Autoinducer-3 (AI-3)
• Autoinducing polypeptide (AIP) - Gram positive cells
• Autoinducer-2 (AI-2) - Gram positive as well as Gram negative cells
• AI-2 :- Interspecies communication
• AIP system:-Intraspecies communication
(Smith et al., 2004)
QUORUM SENSING SIGNALS
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11. CONT….
(Auger et al., 2006)
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12. MECHANISM OF QUORUM SENSING
Acyl-Homoserine Lactone
(AHL) dependent
AutoinducerPeptide
(AIP) dependent
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13. SIGNALLING MOLECULES
1) Autoinducer 1:
 Major group:- Acyl homoserine lactones
 Conserved homoserine lactone (HSL) ring with a acyl side chain
 Provide variation and specificity for quorum-sensing communication in a mixed bacterial
population
N-butyryl-L-Homoserine lactone
(Shaw et al., 1997)
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14. SIGNAL MOLECULES IN AHL DEPENDENT QS
(Raina et al., 2009)
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15. Autoinducing Peptides:-
 Utilized by Gram-positive species
 Modified peptides for cell to cell signalling
 Exported via ATP- binding cassette (ABC)-type transporters
Oligopeptide synthesized by S.aureus
(Shaw et al., 1997)
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16. 1) AHL DEPENDENT MECHANISM IN GRAM –VE BACTERIA
Autoinducers- acylhomoserine lactones
AHLs diffuses extracellular
and intracellular via passive
transport.
Concentration of these signaling molecules
exceed threshold value
Molecules are internalized in the cell and
activate particular set of genes in all bacterial
population
promoter
(https://openwetware.org/wiki/CH391L/S13/
QuorumSensing accessed on 14th April, 2018)
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17. 2) AIP DEPENDENT MECHANISM OF QS IN GRAM +VE BACTERIA
Autoinducers:- polypeptides
Require specific peptide exporters
Bind to autoinducer receotors on the
surface of the bacterium
Critical level of oligopeptide is reached
Binding of the oligopeptide to its
Receptor
Starts a phosphorylation
Cascade
Activates DNA binding
transcriptional regulatory protein
(Response Regulators)
(https://www.researchgate.net/profile/Chong
_Lek_Koh, accessed on 15th April, 2018)
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ATP
ADP

18. QUORUM SENSING MEDIATED PHENOMENONS
IN DAIRY AND FOOD INDUSTRY
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19. QS regulated traits include
 Biofilm formation
 Acid stress tolerance
 Bacteriocin production
 Competence adhesion
QS has been involved in the production of a number of
different fermented foods
 Fermented fruits and vegetables
 Sourdough
 Dairy products
 Wine
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20. Food matrix Microorganisms QS system QS effect
Smear ripened
cheese
Gram positive
coryneforms and
staphylococci
AI-2 • AI-2 activity found in, C.
ammoniagenes, C. casei, M.
barkeri, M. gubbeenense, S.
equorum subsp.Linens
Smear ripened
cheese
Yeast PEOH, TOL,
TYR, FAR
• PEOH and TYR were produced by D.
hansenii
• PEOH, TOL, TYR and FAR influenced
adhesion and sliding motility
QS within microbial communities in fermented DAIRY foods
(Gori et al., 2011)
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21. Smear ripened
cheese
Yeasts Ammonia • Ammonia was produced by D. hansenii, S.
cerevisiae, and G. candidum
Probiotics Probiotic LAB AI-2 • AI-2 activity found in L. rhamnosus
Probiotic LAB AI-2 • AI-2 activity found in L. rhamnosus,
L. salivarius, L. acidophilus and L. johnsonii
• AI-2 activity and transcription of luxS were
induced upon acid shock
(Gori et al., 2007)
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22. Sourdough LAB AIP (Plantaricin) AIP produced by L. plantarum inhibited
L. sanfranciscensis and P. pentosaceus
Chinese fermented
meat
LAB AI-2 AI-2 activity found in L. plantarum and L.
sakei
Synthetic wine Yeast PEOH, TYR, TOL QS kinetics for S. cerevisiae correlated with
transcription of genes involved in PEOH,
TYR and TOL synthesis (ARO8, ARO9,
ARO10)
(Di Cango et al., 2009)
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23. PROBIOTICS AND QUORUM SENSING
• Beneficial effects of probiotics through quorum sensing
• Symbiotic gut microorganisms release:- surface and exogenous proteins, nucleases,
peptides, fatty and amino acids etc.
• Able to sense environment
• Interact with corresponding cell surface, membrane, cytoplasm and nucleic acid
receptors
• Reply quickly and co-ordinately by induction of special sets of genes
• Supports stability of host genome
(Freitas et al., 2003)
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24. • Production of ‘Modulins’
• Act directly on host cell functions
• Host cell biochemical pathways are specifically modified by these “modulins”
• The luxS gene: role in acidic stress response in probiotic lactobacilli easing their survival
in gut
(Moslehi et al., 2009)
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25. QS and BACTERIOCIN PRODUCTION
 Gram-positive lactic acid bacteria secrete antimicrobial peptides (AMPs) , regulated by QS
mechanisms
(Klaenhammer,1993)
 Nisin: synthesised by Lactococcus lactis
 Biosynthesis of nisin : the gene cluster nisABTCIPRKFEG
(Kleerebezemand Quadri, 2001)
 Nisin synthesis
 Early- to mid-logarithmic phase
 Increases to a maximal production level in the early stationary phase when the highest cell
density is reached
(Kuipers et al., 1995)
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26. Fig. nisin production (Quadri, 2002)
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27. SPOILAGE OF MILK AND MILK PRODUCTS
Serratia proteamaculans strainB5a
 AHL based QS system
 Spoilage of milk by Serratia spp.
(Christensen et al., 2003)
Psychrotrophic bacteria Pseudomonas spp., Enterobacter spp.
 AHL based quorum sensing
 Spoilage of milk and dairy products
(Whitfield et al., 2000)
Pseudomonas
 Signal molecule hexanoyl homoserine lactone
 Spoilage of fermented milks
(Shobharaniet al., 2010)
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28. SPOILAGE OF FRUITS AND VEGETABLES
 Erwinia and Pseudomonas
 AHLs (mainly 3-oxo-C6-HSL and C6-HSL) mediated QS
 Spoilage of ready-to-eat vegetables
(Pirhonen et al., 1993)
 Pseudomonadaceae or Enterobacteriaceae (mostly Erwinia spp.)
 High cell densities (108 - 109 CFU /mL)
 Enzymatic browning, off-tastes, off-odors, and/or texture breakdown resulting in their spoilage
(Pirhonen et al., 1993)
 S. marcescens and S.liquefaciens
Secretion of several unrelated and potentially food-quality-relevant proteins
• Lipase LipA
• Metalloprotease PrtA
• Surface-layer protein (S-layer) SlaA
(Riedel et al., 2001)
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29. BIOFILMS AND QUORUM SENSING
(Raina et al., 2009) 29

30. QUORUM SENSING INHIBITION
• Intense search of compounds to block AHL communication
 Quorum-sensing inhibitors
 Degrade signal molecules (Dong et al., 2000)
• Interfere with the receptor protein and the chemical signal
(Manfield et al., 1992)
• Halogenated Furanones produced by the Australian Red Algae (Delsea Pulchra)
(Givskov et al., 1996)
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31. • Extract of vanilla beans in the C. violaceum effectively inhibited bacterial quorum sensing
(Choo et al., 2000)
• Natural furocoumarins from grapefruit juice act as the inhibitors of AI-1 and AI-2 activity in
S. typhimurium and P. aeruginosa
(Girennavar et al., 2008)
• Dietary phytochemicals from plants :-Quorum-sensing inhibitory activity at sublethal
concentrations
(Choo et al., 2000)
 Orange extract enriched in O-glycosylated flavonones
Naringin, Neohesperidin,and Hesperidin
QS inhibitory capacity against C.violaceum
(Givskov et al., 1996)
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32. CONCLUSIONS and future perspectives
 Collective behaviour – cell to cell communication
 Scientific phenomenon in most of the terminologies
 Quality of the fermented food could be increased by QS modulation
 Future emphasis is needed on studies related to multi-species or multi-kingdom
communities
 Health benefits of QS molecules should be studied
 For food spoilage prevention, study related to QS inhibition is needed
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33. THANK YOU33