Use of microwave for disinfection

[TJ]

I've read the thread on this subject at:

http://www.caudata.org/forum/messages/8/13788.html

...but instead of dismissing the microwave oven altogether as a means of disinfection, what would fall into the safe use category? After reading the following article, I'm thinking of microwaving sponge filters removed in the past from tanks in which a newt had died or fallen ill.

<font size="-2">Microwave zaps germs on sponges
(Reuters)

WASHINGTON - Two minutes in a microwave oven can sterilize most household sponges, U.S. researchers reported on Monday.

A team of engineering researchers at the University of Florida found that two minutes of microwaving on full power killed or inactivated more than 99 percent of bacteria, viruses or parasites, as well as spores, on a kitchen sponge.

"People often put their sponges and scrubbers in the dishwasher, but if they really want to decontaminate them and not just clean them, they should use the microwave," said Gabriel Bitton, a professor of environmental engineering who led the study.

Writing in the Journal of Environmental Health, Bitton and colleagues said they soaked sponges and scrubbing pads in raw wastewater containing fecal bacteria such as E. coli, viruses, protozoan parasites and bacterial spores.

Then they used a common household microwave oven to heat up the sponges. It took four to 10 minutes to kill all the spores but everything else was killed after two, they said.

"The microwave is a very powerful and an inexpensive tool for sterilization," Bitton said. </font>

Also, need I wet the sponges before putting them inside the microwave in order for this to be effective?

 

[alan]

As a professional microbiologist, I can tell you that microwaving will not sterilize as it won't touch spore forming organizms. Also:
http://news.bbc.co.uk/1/hi/health/6293735.stm

 

[jim]

It seems an article recently came out about this and a local radio show here in houston made mention of it. They forgot to mention however, that the sponge does need to be wet or it will burn or melt, which has been happening all over the country since this article came out

(And after reading Alans link I see its not just the U.S.)

 

[TJ]

Thanks for that info, Alan and Jim. And nice link, Alan!

Guess I'll just boil those sponge filters then

Any idea how long the process should continue once the water reaches the boiling point?

I found the following cautionary advice on the Web:

"To guard against the risk of fire, people who wish to sterilize their sponges at home must ensure the sponge is completely wet. Two minutes of microwaving is sufficient for most sterilization. Sponges should also have no metallic content. Last, people should be careful when removing the sponge from the microwave as it will be hot."

(Message edited by TJ on January 26, 2007)

 

[jennifer]

I'd suggest bringing the water to a good boil first, then immersing the sponge for a minute or two. I suppose that to kill all spores, you'd have to boil for 10 minutes, but I think spores will get into your aquariums (through the air) no matter what you do.

 

[rodrigo]

I´ve seen how completely sterilized tanks, with treated new water, and just gravel, developed fungus...so there´s not much you can do... No matter how strict you are with sterilizing the spores will find their way hehe...

 

[TJ]

What kind of disease-causing fungi are we talking about here in which spores are transmitted through the air from tank to tank? I was only thinking about bacteria when I started this thread

Even with chytrid fungus, I've not heard of spores being transferred through means other than water or direct amphibian-to-amphibian contact...not that I don't believe it, just hadn't heard of it!

 

[abrahm]

Well, if there was a case of bacteria or fungi in your tank it would be reasonably easy to aerosolize them with an airstone which could lead to contamination of other tanks. Or the spores could land on other surfaces which could then be added to the tanks. Bacterial spores are remarkably resilient structures (I know little about fungal spores or protozoan cysts.) Autoclaving is one of the most reliable ways of destroying them. If you have a small pressure cooker this would work even better than boiling alone. I'd be worried about melting your sponge either way.

 

[TJ]

Thanks Abrahm, bacterial spores didn't occur to me

I wasn't aware that bacteria that can cause diseases in amphibians can be transmitted from tank to tank simply by virtue of the tanks being in the same room together, even when precautions are taken to ensure against contamination via water or shared implements. What are the names of some of these diseases that can be contracted by captive amphibians through air-borne contaminants? I haven't heard of chytrid being spread that way.