Quorum Sensing Inhibition
of Vibrio alginolyticus from
Caulerpa lentillifera (Lato)
on Pseudomonas aeruginosa
Arbo, Ma. Adelle Gia T.
Arteta, Allen O.
Belmonte, Pauline Marie C.
What is Quorum Sensing?
 accumulation of signaling molecules
enabling a single cell to sense the
population density (Bhattacharya et al,
2008, pp. 30)
 production and release of chemical
signal molecules called autoinducers to
coordinate gene expression
 significant in biofilm formation and
virulence of some microorganisms
Pseudomonas aeruginosa
Figure 1. Pseudomonas aeruginosa
(http://textbookofbacteriology.net/pseu
domonas.html)
an opportunistic
bacterium that uses
quorum sensing in the
formation of biofilms,
swarming motility,
expolysaccharide
production, and cell
aggregation.
(Bhattacharyya et al,
2008, pp. 30-33)
Related Studies
 Givskov, Michael et al (2006)
-quorum sensing signaling systems of
pathogens were used as central
regulators for the expression of
virulence factors
-Quorum sensing inhibitors compounds are capable of reducing
virulence and be used as treatment
 Joint, Ian et al (2007)
-the green seaweed Ulva has
been shown to detect Nacylhomoserine lactones
(AHLs)
Seaweeds
 suitable substrate
http://davaoorientalinvest.com/main/?page_id=121
Figure 2. Seaweeds
for epibiotic
organisms because
it releases a large
amount of carbon
into the
surrounding
environment
Caulerpa
lentillifera
•abundant in the
Philippines and
cultivated as food
and sold fresh and
salted
http://www.mesa.edu.au/marine_algae/gallery.asp)
Figure 3. Caulerpa lentillifera
Vibrio
alginolyticus
 a gram negative
bacterium usually isolated
from the surface of marine
organisms such as
seaweeds and stony corals
 Some Vibrio species have
quorum sensing inhibiting
ability
Statement of the Problem
Main Problem:
Is Vibrio alginolyticus from
seaweed, Caulerpa
lentillifera capable of
inhibiting the quorum
sensing of Pseudomonas
aeruginosa?
Specific Problems:
1. Are there zones of inhibition exhibited
by Vibrio alginolyticus on
Chromobacterium violaceum after agar
overlay technique?
2. Are there zones of inhibition exhibited
by Vibrio alginolyticus on Pseudomonas
aeruginosa after agar overlay technique?
Significance of the Study
seaweed farmers
antimicrobial agents
 economy
Pharmacology
Scope and Limitation
Scope
Limitation
 Quorum sensing
inhibition assay
 antibacterial assay
 time
 observation time
 seaweed Caulerpa
lentillifera
 use of indicator
Chromobacterium
violaceum 12472
 use of lb broth
Research Design
R X1
R X2
O1
O2
Where:
O1 & O2 = posttest observation
X1 = quorum sensing inhibition assay
X2 = antibacterial assay
Research Paradigm
Linking Variables
Agar overlay of
Pseudomonas aeruginosa
and Chromobacterium
violaceum
Zones of inhibition of
Pseudomonas
aeruginosa and
Quorum sensing
systems of
Pseudomonas
aeruginosa;
Chromobacteriumviolac
eum 12472, Vibrio
alginolyticus
Independent
Variables
Chromobacterium
violaceum 12472
Signaling molecules and
growth conditions of the
bacteria
Extraneous Variables
Figure 4. Research Paradigm
Dependent
Variables
Treatment/
General Procedure
Isolation of Vibrio alginolyticus
Figure 5. Taking samples of
bacteria from Caulerpa
lentillifera
Figure 6. Agar plate inoculated
with bacteria from Caulerpa
lentillifera
A. Quorum Sensing Inhibition Assay
Preparation of Marine agar
plates and lb broth
Inoculation of
Chromobacterium
violaceum 12472 and
Vibrio alginolyticus on lb
broth and marine agar,
respectively
Figure 7. Plate inoculated with
C. violaceum and P. aeruginosa
Figure 8. Inoculating lb
broth with C. violaceum
24- Hour incubation
Overlay of lb broth on the
marine agar plates inoculated
with Vibrio alginolyticus
24- Hour incubation
Figure 9. Test tube inoculated
with C. violaceum
Figure 10. Overlay of lb
broth on marine agar
after 24 hours.
Observation and Data
Gathering
B. Agar Overlay of Pseudomonas
aeruginosa
Preparation of marine agar
plates and trypticase soy broth
Inoculation of Vibrio
alginolyticus on marine agar
and of Pseudomonas
aeruginosa on trypticase soy
agar
Figure 11. TSB inoculated
with Pseudomonas
aeruginosa
Figure 12 Marine agar
inoculated with Vibrio
alginolyticus
24-hour incubation
Overlay of trypticase soy on
marine agar plates
24-hour incubation
Figure 13. Agar overlay of
Pseudomonas aeruginosa
Figure 14. Overlay of TSB on
marine agar after 24 hours
Observation and Data
Gathering
Results and Discussion
There was no noticeable zone of inhibition
induced by Vibrio alginolyticus on both
Chromobacterium violaceum and
Pseudomonas aeruginosa.
Figure 15. Marine agar plate of
Vibrio alginolyticus after agar
overlay of Chromobacterium
violaceum
Figure 16. Marine agar plate of
Vibrio alginolyticus after agar
overlay of Chromobacterium
violaceum
 no verification that
organisms had quorum
sensing at that time
 mutations of organisms
 population of organisms
 conditions of bacterial
growth
Recommendations
 Further understanding
of quorum sensing
 isolate more organisms
 exploit other
techniques
Let us take
this vital
step
together!
Thank
you for
listening!