Swarm Assays

STARTED 2008-09-27

Test of the abbility of strains expressing the fusion receptor, to move against an attractant gradient.

As autoinducer 2 producing attactant strain DH5α was used.
The fusion receptor plasmid was further cloned into HCB33 and UU1250 strains.

Petri-dishes were used es running chambers.
A petri-dish was filled with a media containig agar. Then the attractant was spotted on premarked positions or spotted as a line through the center of the petri-dish. After the gradient of the attractant has etablished the strains whioch should be attracted by the attractant where also set on premarked positions. The whole petri-dish was incubated at 37 °C and pictures were taken after 24, 48 and 72 hours.

A few pictures which have been taken during these experiments can be viewed under Projects and Methods.

First swarm plates

A swarm assay test in 4 swarm plates was prepared.
2 different fusion constructs were used. Each in HCB33 and in UU1250.
Every petri-dish was filled with 20 ml of media. Two with minimal media containing about 0.3 % agar and the other two with TB media containing 0.2 % agar.

On a center line of both minimal plates and on one of the TB plates two spots of DH5α were created.
Afterwards fusion contruct 1 containing bacteria HCB33 and UU1250 were each spotted on the right half with an equal distance to the attractant spots. The same was done with the fusion construct 2 containing bacteria strains, but on the other half of the plate.

Up to now

Further swarm plates have been prepared testing different media and increasing the volume to 25 ml. A new spotting method of the attractant has been used by creating an attractant line through the center of the petri-dish.
So up to now a general protocol with which further swarm assys can be created step by step has been established.
The latest protocol can be viewed under the topic of swarm assays on Methods.

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