The literature I've researched says that biofilms are attached to the bottom of the petri dish, so why is the biofilm of my Porphyromonas gingivalis culture floating on the surface of the medium? Is there something wrong with the type of medium I am using?
I do not understand what you mean by floating on the surface of the culture medium. Floatation has to do with liquids if science has not changed from that. You talk about a Petri dish, so I assume a solid medium immediately. There can only be floatation if the biofilm obeys the law of floatation and the buoyant density of the microbial community is low enough to allow floatation in LIQUIDS. Again, the bacterium in question is an anaerobe, which presupposes that it has little or no requirement for oxygen. Maybe, it is because it is aerotolerant then, after all, the Streptococci are also there. Finally, that biofilms attach to surfaces does not mean they have to be found under or below surfaces. They attach to solid supports like Petri dishes. Please clarify what you mean by surface of culture medium.
Maurice Ekpenyong ，thanks for your answer.
My main question is whether the biofilms produced by porphyromonas gingivalis stick to the bottom of the 35mm cell dishes or float on the BHI broth.
Because the literature I reviewed says that Porphyromonas gingivalis is a late stage colonizing bacterium that has no flagella and usually relies on the help of other bacteria to form biofilms. And in my experiment, I'm currently doing experiments to test biofilm production by Porphyromonas gingivalis with crystalline violet. And I'm using a bacterial concentration of 10^8, cultured in 35mm cell dishes with BHI broth.
I found that after 48h, the surface of the BHI broth will produce a film, like a tissue film floating on the liquid. Is this a biofilm, please? I am guessing that maybe the dead bacteria are clumped together and floating on the liquid, not a biofilm.
My guess is that the concentration of the bacterial solution I used is too high or the incubation time is too long, causing the bacteria to overgrow and die. If I adjust the incubation time to 24h, maybe a film is created at the bottom of the 35mm cell dishes ?
look forward to your answer.@@
All your thoughts could be investigated. So you actually put a broth into a plate to simulate say a stagnant liquid. That's OK. I doubt very much if the float is a biofilm, otherwise, it will negate the definition of biofilms. It has to be attached to solid support. Don't forget that. could be dead cells (debris) but not biofilms.
Is it on the liquid-air interface? Could you share an image of it?
I don't think the film growing on the liquid surface is produced by P. gingivalis.
Could you please share which P. gingivalis strain is this?
- You can also check for contamination by other aerobic bacteria (for example do gram stain to the sample from this film)
- Do you made a negative control (medium without bacteria in the same condition) ?
Marwan M. A. Mohammed Gabriel Magno de Freitas Almeida
I am trying to grow biofilm on the surface of 35mm cell dishes, I chose P. gingivalis ATCC33277, and use BHI medium with vitamin k1 and Chlorine heme. But the bacteria are in planktonic state, instead of biofilm state. Does anyone have experience? Thank you very much.
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