Quorum Sensing

5. Bath sonicator (for environmental biofilm samples): We have
   found it important to use glass vials rather than plastic as the
   latter substance (plastic) dampens the shear forces generated by
   the sonicator and reduces biofilm disruption.


6. Small glass vials for storing extracted AHLs (scintillation vials
   with autoclavable polycarbonate lids are excellent general-
   purpose containers in this regard).


7. Water aspirator or vacuum source (use water trap to avoid
   contamination of vacuum line).


8. Rotary evaporator.


9. Freezer (preferably 80 C).

2.2 A. tumefaciens
Assay for AHLs

1.A. tumefaciensA136 (pCF218)(pCF372) (biosensor strain):

Maintain on LB supplemented with spectinomycin (50μg/ml)

and tetracycline (4.5μg/ml) [29, 35].

2.A. tumefaciens KYC55 (pJZ372)(pJZ384)(pJZ410) (alter-

nate, highly sensitive biosensor strain): Maintain on LB supple-

mented with spectinomycin (50μg/ml), tetracycline (4.5μg/

ml), and gentamycin (15μg/ml) [30].

3.A. tumefaciensNTL4 (pCF218)(pCF372) (biosensor strain

that does not spontaneously mutate for tetracycline resistance):

Maintain on LB supplemented with spectinomycin (50μg/ml)

and tetracycline (4.5μg/ml) [36, 37].

0.25

0.20

Control

0.5X

1.5X

1X

0.15

0.10

LB R2A Davis MM

Media

OD600

0.05

0.00

Fig. 6Representative dispersion screen showing the ability of a potential novel dispersion agent at various
concentrations [59] to detach preformedP. aeruginosabiofilms that were grown in Luria-Bertani (LB) broth,
R2A broth, or Davis minimal media (Davis MM). Detachment is indicated by increased turbidity

12 Starla G. Thornhill and Robert J.C. McLean