Coordinated bacterial behaviour

Swarming motilityBiofilm formation

Symbiosis Pathogenicity

Fruit bodyformation

Bioluminescence

Quorum Sensing= Intercellular Signaling

Wound infection Skin diseases

Yoghurt production

after 3 d on agar

activation

Sin quorum sensing: a system of transcription control

WT

sinI-

expR-

sinR-

QS behaviour

SinISinR

AHLs

AHLs

AHLs

AHLs

nutrient limitation

ExpRAHLs

AHLs

A more detaileddescription

SinISinR

ExpR

resting state

SinISinR

AHLs

ExpR

nutrient limitation

positive feedback

negative feedback

SinISinR

AHLs

AHLsExpR

SinR

AHLs

ExpRAHLs

expression of green fluorescent protein fromthe sinI promoter

0 10 20 300

5000

10000

15000

20000

sinI promoter-egfp fusion

time (hours)

F/c

ell

log growth intermediate growth stat. phase

resting state nutrient limitation activation positive feeback negative feedback

AHL concentration 0-5 nM 5-20 nM 20-1000 nMin growth medium:

SinISinR

ExpR

SinISinR

AHLs

ExpR

nutrient limitation

SinISinR

AHLs

AHLsExpR

SinR

AHLs

ExpRAHLs

intermediate stagelog growthlog growthstat. phase & lag phase