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plant infections - (Nov/22/2010 )

Hallo all,

I started an in vitro culture of some plants, now I noticed some contamination..

I know that some of the contaminants are fungi and other are bacteria..
But is is possible to have an idea about what bacteria-fungi it might be?
(lets say: types of bacteria that are common for this kind of infections?)

Or are there really too much bacteria-fungi that can cause this?

Another question is about what other contaminants could it be? Is it likely that I can have a contamination of yeasts? Or maybe even mites?
(Mites should come from the plant material itself, but this is desinfected...)

I also noticed my medium turning black in one contaminated sample.. why is this? I suppose its because of the contaminant making some metabolites ? But are those changing the color because a pH shift or? (I am using MS medium).

Thanks in advance.


So for the fungi: if you contaminant is turning black, I would suspect you have something that is collectively referred to as "dark septate endophytes" in your culture. But as you mentioned the black could be a metabolite itself, this is difficult to assess without seeing your samples.


The medium is black , but the contaminant? You mean that the fungus is black ?

And I have tried to take pictures, but they are not clear.

The most bacteria I see are brownish (light brown, dark "dirty" white).

Anyway, I conclude that its impossible to really point down a certain type of infectant and that it can be anything..
(or are there types of fungi, bacteria that are known for their contamination of plants? Or are associated with plantmaterial)

One more question: is it possible to see if the contaminant came from the plant itself or the medium?
(I was simply thinking that when you see the bacteria or fungi mostly at the plantsample itself that its from the plant..)


If you keep a spare plate with medium from the start of the exp, you will be able to rule a contaminated medium out.


I have such a sample.. however that doenst rule out the fact that I might have contaminated my samples while working on them under the LAF.

and what do you mean with "the contaminant" : you mean the fungus or the infected sample ? (do you mean that the fungus turns black or the medium?)


no idea, both can happen. there are black fungi and yeasts and there are fungi that can exudate black substances...