Lab Equipment: baby bottle autoclave / sterilizer

[Mackenzie Cowell]

Hey list,

I love threads about lab hardware (like this recent one: https://groups.google.com/d/topic/diybio/jFARFnazXFo/discussion).

What is the collective opinion on consumer-grade steam sterilizers made for sterilizing plastic breastmilk / formula for babies?  They are inexpensive (less than $100) relative to pro-grade steam sterilizers and autoclaves, but I don't think they increase atmospheric pressure - they just steam the sterilization chamber for 6 minutes.  Example: http://www.amazon.com/dp/B0057ECYS0 .

Under what conditions in a molecular biology lab is sterilization of equipment at 1 ATM with steam for 6 minutes sufficient, instead of 17 PSI (1.157 ATM) steam for 20 min?  One problem right off the bat is that these consumer-grade sterilizers wouldn't be able to sterilize media by bringing it to a boil, and by the same token probably couldn't sterilize waste.  But they probably could sterilize empty bottles / tips / tubes etc.  The bottles that come with the system might even be useful for storing media!  Much cheaper than glassware.

What do you all use for autoclave equipment?  Something like this $600 Pressure Sterilizer made by All-American Corp http://www.amazon.com/dp/B00284BJOM seems popular?

Looking forward to hearing what you all use for sterilization.

Mac

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[Brian Degger]

I have been using a 12L pressure cooker on a gas hob. Recently however I saw a digital pressure cooker with integrated heating. That looks much better as it automates the process, and dosen't require extra infrastructure. A quick search on ebay.co.uk brought up this one http://www.ebay.co.uk/itm/SKG-Stainless-Steel-4L-Electric-Pressure-Cooker-A402B-/271054392179#vi-content. Downside would be that their size is a lot smaller limiting the amount that can be sterilized at one time.

Cheers

Brian

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[Sebastian Cocioba]

I use a prestige medical autoclave for media and an all American (biggest one) for glass since I can't trust the analog gauge on it. I'll slap a nice thermocouple and arduino on it and make it legit but for now the prestige works wonders although only fits one 1L Pyrex bottle at a time. I do large volume plant tissue culture so the all American is the most spacious for the price. I just let that baby run for 1hr and bam. Sterility.

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[Dakota]

You might check out  http://www.hometissueculture.org/ if you're into tissue culture.

http://tech.groups.yahoo.com/group/hometissueculture/ 

I don't know much about it but there is something really sci-fi looking and super cool to me about plants growing in test tubes on invisible agar.   Been following the group for a year + and some day I'll give it a shot.  You have any cool pictures of the TC you do?

[John Griessen]

On 09/18/2012 07:35 PM, Brian Degger wrote:
> Recently however I saw a digital pressure cooker with integrated heating. That looks much better as it automates the process, and
> dosen't require extra infrastructure.

I just saw something to consider: microwave pressure cooker made of phenolic/metal with all parts compatible with microwaves.
Has weight-based pressure regulator and pressure safety and lid safety pressure valves and pressure down indicator.
The microwave timer might be enough "automation". Same drawback of small size -- this one was maybe 18 cm across 13 cm high
rounded interior. It was $5 at a thrift store -- anyone want me to pack send it in the US?

[Cathal Garvey]

We had a thread a while back where we shared some papers on pure
microwave sterilisation; apparently the measurable efficiency of
sterilisation is comparable using a regular microwave vs. a pressure
cooker when you're sterilising volumes less than ~100mls.

So, this can only improve, IMO, when using a steam container like those
bottle sterilisers. We have a plastic one we used early on for my
daughter (against my microbiologist bugs-are-good-for-you objections
:P), but I haven't nicked it for testing in the lab yet...

www.indiebiotech.com
twitter.com/onetruecathal
joindiaspora.com/u/cathalgarvey
PGP Public Key: http://bit.ly/CathalGKey

[Mackenzie Cowell]

Imagine you have a 500 mL beaker filled with used pipette tips, amp agar colonized with transformed k12 from small petri dishes, gels with DNA and gelgreen / sybrsafe... this all could be disposed of as normal waste by sterilization with a pressure sterilizer or an autoclave.  What about just microwaves, or microwaves and 1 ATM steam?

A good question for biosafety professionals.

Mac  

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[Gavin Scott]

On Friday, September 21, 2012 1:50:05 PM UTC-5, Mackenzie Cowell wrote:

Imagine you have a 500 mL beaker filled with used pipette tips, amp agar colonized with transformed k12 from small petri dishes, gels with DNA and gelgreen / sybrsafe... this all could be disposed of as normal waste by sterilization with a pressure sterilizer or an autoclave.  What about just microwaves, or microwaves and 1 ATM steam?

Well, I don't know, but I really doubt you're going to achieve anything close to sterilization that way. I think the best you're going to do is boiling the environment in the beaker. I'm not sure the microwaves are going to couple to individual critters with any degree of efficiency, and there's probably a big danger of nulls in the microwave field that would allow pockets of survivability.

If your beaker is wet enough then it's just going to boil. If it's dry enough then you probably don't present enough of a load on the magnetron output and the high SWR fries your oven if you run it very long that way.

As I said, I don't know, but it sure sounds sketchy to me.

G.

[Matt Lawes]

The baby bottle sterilizer approach (wet steam) will work for the dry materials like pipettor tips and glassware. The agar plates though ..... not a chance. The microwave will definitely melt the agar in the plates with the e coli but I think you'll need some way to create pressure as well as boiling liquid. Perhaps if you put in a Pyrex dish with sealing plastic lid. Put everything in the Pyrex dish and a little water in the bottom to create steam. Heat in the microwave until boiling and keep it going for about 15 - 20 minutes. You can always test for ecoli culturability from the waste to assess sterility. Just a guess ..... but I bet you can optimize from there.

>matt

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[Nathan McCorkle]

I can fit a 500ml beaker in my $30 pressure cooker from Walmart

[Matt Lawes]

That would work the best for sure. Good insight! Pressure plus steam will do the job. Historically there were bench top Autoclaves ....... look exactly like a pressure cooker.

>matt

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To: "diy...@googlegroups.com" <diy...@googlegroups.com>
Sent: Fri, Sep 21, 2012 19:39:14 EDT
Subject: Re: [DIYbio] Lab Equipment: baby bottle autoclave / sterilizer

[Cathal Garvey (Android)]

I thought the same, but I've got a few papers now suggesting otherwise. It's possible it's something particular to microwaves, that they internally damage spores more quickly than externally applied heat might do.

None of the papers offered explanation anyway. Just evidence that, if you use small volumes and account for hotspots, it compares well to autoclaving (but takes a fraction of the time).

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[John Griessen]

On 09/22/2012 05:15 AM, Cathal Garvey (Android) wrote:
> None of the papers offered explanation anyway. Just evidence that, if you use small volumes and account for hotspots, it compares
> well to autoclaving (but takes a fraction of the time).

Microwaving does flow energy quickly -- and right where you want it -- to the water. The generated steam
from cooking has to flow out of any container, so it spreads heat out, equalizes temperature.


If you wanted a higher peak
temperature, a mini pressure cooker in the microwave oven seems useful, and pressure cookers made for microwave use
are for sale now.