The details on this picture with many air bubbles are not enough to identify the culture morphologically.

Hi Shima, I am guessing Rhizopus spp!!. Rhizopus spp are common moulds and laboratory contaminants and they produce bubbles like these in your picture.

There are prominent bubbles in between the mycelium, which I thought was hyphal swellings. They start out round, but get bigger and misshapen. The media is darkly pigmented too over time. Though I did not see any characteristic fruiting body and mycelium is aseptate. Thanks for the answer.

I don't think so.

And by the way, Penicillium species have septate mycelium!

Dear, Shima,

Maybe you may try other medium to stimulate sporulation?

And place here at least the photo of the whole colony? Some data on growthrates and so on?

That would help in identification

I do not think it is Penicillium, I will try to take better resolution picture and post. I do not see any reproductive structure in the culture at this time. I have isolated my Phytophthora from soil, and this fungus is forming aerial hyphae. The bubbles can form mycelium when transferred to another plate. Thanks for the answer, The picture is of my plate viewed through stereoscopic microscope.

I also think about Zygomycetes, as Rachid suggested, or maybe oomycetes although waiting for more information

The absence of any identifiable spore makes identification difficult. It is also not clear if the mycelium is septate or aseptate despite dichotomous branching in some areas. I would advice that the organism be subculture on other media that might support sporulation. Culture characteristics to noted and firsthand microscopic recorded for better identification.

Thanks, I will try to subculture. Do you have any suggestion of media that I can use to cause sporulation.

First try  Czapek agar, or any other standard media for 

Find it difficult to  makeout  as there is   any identifiable spores. Better to sub culture and carry out  culture studies for better identification.

Thanks for you all to answer, I will get back with better resolution pictures and try to see if I can cause sporulation.

Prepare a micro culture of contaminating fungus to reveal its identity under the microscope.

Dear, its structure look like Paecelomyces..but not sure since spore is not present..

Thanks,

I am planning to induce sporulation, and I agree, the picture need greater resolution. But working on it, and soon will give more information on it.

Looks like a phialidic hyphomycete but as others say the resolution and characters are not sufficient for identification in this form. Recommend growing on a low-sugar medium like PCA (potato carrot agar) for a week or so, incubate at room temperature and then try to see the ontogeny of spore production and structure of conidiophores/phialides. Good luck.

The identification of that fungus could be OK, but are you really interested to identify it or it is only to eliminate form your Phytophthora cultures? the strategy for each one of the previous things is quite different. 

If elimination is what you are looking for then you may try changing nutrient media parameters such as pH and O-R potential.

I added benomyl to my media, and it is slowing down the contaminant. Plus it is a septate fungi, unlike what I thought earlier. I looked up some images of Phialidic hyphomycete, and I think, it does resembles like the shown in images. My objective is to remove it from my culture as contaminant so I can get pure cultures of Phytophthora isolates. Thanks for all the answers I received through forum.

It may be the species of Acremonium or Fusarium. Please makecorrect and visible slides and deside.

Is hard to see... Send new images...  But it seems an kind of Acremonium sp.

Thanks for responding, now I think it is Acermonium, but problem is how do I clean my culture?

You go for subculturing. Prepare microculture on PDA/ Mycophil agar/Malt agar with added antibiotics or even Saborauds agar.                                                                 Once desired culture of your interest is available with you, try to maintened it in pure form adjusting the parameters such as pH, O-R potential and temperature in particular so as to increase its stability over longer time span.

The phailic characters and branching style of fungus is more closer to Acremonium sp. subculture the specimen and make a rectangle small tunnel in agar medium and inoculate the fungal spores on both sides of tunnel and place a clean cover slip on the tunnel and watch the growth pattern of the fungus under microscope directly and consult "Compendium of Soil Fungi" by Domsch et al. 1980 Academic Press New York.

Probably an hypocrealean conidial fungus. The picture is not clear, but verticillate structures are apparently present. Fungi in the Verticillium or Acremonium group should be considered.