The effect of cellulase on E. Coli

[Etherian]

For a science fair project, my group was testing to see how the enzyme cellulase would affect the effectiveness of bleach at killing bacteria in a biofilm, as biofilms are made of cellulose. Our final procedure included inoculating microscope slides with E. Coli K12 and bathing them in lysogenic broth mixed with cellulase, weak bleach, or both. On the controls we observed the expected large clusters of bacteria, which we assumed to be biofilms, but on the slides treated with only cellulase we were surprised to find that there were no bacteria whatsoever. Instead the slides were covered in clumps a strange material that looked like lint or broken glass. The cellulase + bleach group showed similar results, while the group with just bleach still had a small amount of weak bacteria.
Though we already turned in our paper, I'm curious. Do you have any idea how the cellulase might have killed the bacteria or what that fuzzy looking material was?

[JackBean]

It did obviously degrade the cellulose in cell wall and thus the bacteria lysed

[sunghoo]

Immobilisation of an enzyme by E coli?

[hokosan]

E. coli is a gram-negative bacteria, so there is no cellulose existing in its cell wall.

[canalon]

I doubt that the EPS (exopolysacharide) forming the matrix of E. coli Biofilm is made of cellulose either.
And maybe you just observed dust on your slides, with your cellulase buffer having washed away he bacteria?
By the way clumps are not biofilm, the best way to observe biofilms is to put a (sterile) glass plate in your broth and to let bacteria adhere strongly (it will take a few days). The clumps are probably not full blown biofilms. But in any case cellulose is not likely to be there in large quantity. Maybe the buffer in which your enzyme was, was a bit too strong?
And one final point what the hell are 'weak bacteria' ?

[bellyjelly]

I know that Cellulase enzymes that break down cellulose and are involved in cell wall breakdown in higher plants, especially during abscission. Produced in large amounts by certain fungi and bacteria.
degradation of cellulose microfibrils requires the concerted action of several cellulases.

[JackBean]

Really? Good for you

[Fadilosman]

I doubt that the EPS (exopolysacharide) forming the matrix of E. coli Biofilm is made of cellulose either.
And maybe you just observed dust on your slides, with your cellulase buffer having washed away he bacteria?
By the way clumps are not biofilm, the best way to observe biofilms is to put a (sterile) glass plate in your broth and to let bacteria adhere strongly (it will take a few days). The clumps are probably not full blown biofilms. But in any case cellulose is not likely to be there in large quantity. Maybe the buffer in which your enzyme was, was a bit too strong?
And one final point what the hell are 'weak bacteria' ?

[canalon]

:)

[...]

Your point being?

[DanielSan]

Cellulase alone should have no effect on the growth of E. coli. Recently i worked with yeast which i cultivated in the presence of a nasty hemicellulase/cellulase mix - and that did not affect the yeast growth.
However, if you obtained the cellulase from a commercial supplier, there`s a good chance that it is not pure. Usually they sell only partially purified preparations or even supernatants from cellulase-overexpressing fungi such as Trichoderma or Aspergillus. Under certain conditions, some of these fungi can also secrete muramidases, which degrade bacterial cell walls. That might be an explanation...