# white crust on top of culture, mold?



## Dendrobait (May 29, 2005)

Set up a culture two days ago and noticed it had a white film on the surface. Guessing this is mold? Surprising as it was my first time using Repashy Superfly.


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## Ed (Sep 19, 2004)

Could be just an overgrowth of yeast....


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## Dendrobait (May 29, 2005)

Hmmm...that may have been it. Any distinctive ways to tell? I did not smell anything indicative of mold upon opening the lid-but itd be hard to really sniff without getting flies up your nose so who knows!

I ended up throwing it in the freezer. Maybe I will defrost it and re-add flies. haha Sort of frustrating as I am always a bit short on fly culture containers.

Also, reviewing the ingredients of Repashy superfly I see no indication that they include live yeast. I do not add yeast to my cultures either per your comments on flies introducing it anyway. So for this to happen seems unusual.


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## Ed (Sep 19, 2004)

There are going to be yeast and fungal spores in your house particularly since you culture the flies. People often underestimate how fast yeast can grow if given conditions it likes. 

On the rare occasions I see this happen, I simply let the flies take care of it. The maggots will rapidly churn it under and it doesn't impact the culture. 

The mold to really watch out for is the black Aspergillus (possibly niger). That one acidifies the cultures to eliminate competing microbes and can out grow the flies. 

Some comments 

Ed


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## Dendrobait (May 29, 2005)

Hello Ed,

On Aspergillus-would I be correct to assume that vinegar as a mold inhibitor definitely would not help in dealing with it? Seems that the only solution for that particular one is to throw out all cultures.

Defrosting the culture now. I will start up a couple backups just in case the little experiment fails. 
~Joseph


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## Ed (Sep 19, 2004)

Correct, vinegar does not work to inhibit Aspergillus niger. If I remember correctly, that fungus can take the culture down to a pH of 2 or a little less. I would throw out the culture since opening it to get the flies out would result in a cloud of the spores released into the room. If you get onions and look at them closely, you sometimes see black smudges on them. That can be Aspergillus so that mold's spores are often common in the people's houses.

Some comments 

Ed


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## Dendrobait (May 29, 2005)

Ed: That is pretty impressive. But if it is a common fungus in peoples homes it is also interesting that not too many people have problems with it. I know many people like myself use vinegar in the FF cultures as the only mold inhibitor. I recall making a couple cultures with pure vinegar by mistake and noting decreased production so I'm assuming FF probably don't appreciate the super low ph either. A lot of folk are scared of methyl paraben. 

It seems one thing to do would be to keep your FF's away from your produce and not let things sit around till they start growing mold(one thing college students seem to be great at!). 

Thanks Ed! Always impressed with the constant thoroughness of your answers.


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## Ed (Sep 19, 2004)

Your welcome. 

I'm not sure why people are so scared of methyl paraben/Tegosept. The way it is used in the hobby is surprisingly safe particularly compared to all of the other questionable things people do... 

One of the big changes for people in the hobby is the use of microwaves and boiling water needed for mixing media for the flies. Both of these are going to have level of sterilization for the cultures reducing the risk of mold. 

While I can't prove it, I suspect people are also taking a little more effort to keep utensils and areas clean when making cultures. 

Some comments 

Ed


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## Dendrobait (May 29, 2005)

I'm happy to update this that reseeding the frozen culture(extra dead flies and all) was a success. Lots of larvae. Too early to tell if it is better production-wise than my home mix but I don't see why it wouldn't be based on other peoples observations.

I wonder if feeding larvae out of cultures supplemented with astaxanthin is a more efficient way to get it to the frogs than feeding out adults? Repashy should really grind superpig finer so it sticks better to flies. I find even paracoccus and spirulina don't have quite the affinity that fine calcium powder has though.


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