Dear Saheli, We have spent a lot of time over the past ten years or so looking at the biofilms environmental pseudomonads produce in static liquid microcosms - we have been focussing on biofilms produced at the air-lquid (A-L) interface that some call pellicles, and have found that 60 - 99% of isolates can produce a biofilm of one type or another.

It is very difficult to analyse the EPS produced by an unknown bacteria, unless you are part of a very good organic chemistry laboratory. You can try to extract EPS by spinning down cells and looking at the pellet, or by progressively digesting cells with lysozme, protease, lipase etc., and then look at what you have got left, but all of these procedures presume to some extent that you know what you are looking for. An example of this is our investigation of the biofilms produced by P. fluorescent SBW25. We had genetic information which suggested that the EPS was cellulose or a cellulose-like polymer, and as a result, we were able to design an extraction procedure around this. Although cellulose is the major matrix component in SBW25 biofilms, we know that DNA is there too, and others have reported that SBW25 can express alginate, PEL and PEA, so individual strains may be able to produce quite complex EPS mixtures.

We have also looked at cellulose expression amongst environmental pseudomonads, and have found that 7% or so of isolates express cellulose in colonies or in A-L interface biofilms (mainly fluorescent pseudomonads, excluding P. aeruginosa). We have done this using the fluorescent dye Calcofluor, which is reasonably specific for cellulose, and great fibres and bundles of it should be seen at 10x - 40x magnification with a fluorescent microscope. If you'd like PDFs of some of our papers, please let me know. Regards, Andrew.

Respected Sir

Thanks for your concern.This bacterium which is identified as Pseudomonas mendocina.It forms pellicles at A-L interface.Whole genome of this bacterium has been sequenced and many biofilm forming gene clusters such as pel,alginate,dTDP Rhamnose etc are found.Now i want to extract its EPS and characterise.In this case what will i do?

I will be grateful if you send me the PDFs of those papers at [email protected].

Regards

Saheli Ghosh

As Andrew said, the characterization usually depends on the species and what they are produce in the matrix, and to more extent it depends on the availability of good techniques to distinguish and measure the components.

In my opinion the extraction method is still the main difficult part, which mean how we should separate the cells from the matrix component with no or minimal contamination of lysed cells.

I have done some work with Fusobacterium biofilm, and I just characterized the major components (Carbohydrates, Proteins and DNA) with direct measuring from matrix samples.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3559756/?report=classic

Thanks a lot sir....