Are you using the correct filters? Does your biofilms have sugars recognized by wga and ConA?

Do you have already an idea of what EPS are in your biofilm? My research is quite similar with yours, but in this case we are doing a spectroscopic analysis first in order to have an idea of our biofilm EPS.

I suggest taking a sample to a confocal microscope, where the intensity of the excitation light is stronger. If no signal is detected even using this method, Jorge and Tatiana are probably right, claiming that maybe your EPS does not contain sugar that bind WGA and ConA

Thanks everybody, i would like to try on that way

Hi IqBal ! What strain are you staining ? And hi everybody, do you know any good publication describing methods for EPS staining in biofilms ?

Anybody know how I could do the quorum sensing experiments with Chromobacterium violaceum CV026. Although I have protocol with addition of culture supernatant protocol but it is not working??

Hi Iqbal, do you have positive control for your QS assay with C violaceum strain? For example, use synthesis chemicals such as different homoserine lactone (C4 - C6 ) from Sigma, as positive control. The positive control chemicals may help you find the right experiment conditions such as the density and age of sensor bacteria, incubation time and temp. Also you may use C violaceum 31532 strain as sensor bacteria for positive control. If they don't work, probably your tested bacteria produce different range of QS molecules such as C6-C14 Homoserine lactone or they use AI-2 for signaling. In that case you may need to use other sensor bacteria.

A related paper you may find in http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2075010/

Have you tried staining your EPS using Maneval Capsule Stain? It could be helpful incase the composition of your EPS is unknown. You can observe the clear zone around red bacteria under bright filed microscope.

Tatiana Ramirez, can you share what kind of spectroscopic analysis you do for EPS identification? Do you determine the sugars in EPS?

I stained the proteins in the biofilm matrix using the SYPRO® Ruby Biofilm Matrix Stain, but I didn't try staining of Exopolysaccharide.

Try spectrophotometer