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archivist
5-HT


Registered: 06/06/07
Posts: 1,010
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Germicidal UV lights
#9523877 - 12/31/08 01:44 PM (15 years, 30 days ago) |
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I've read that polystyrene petri dishes are sterilized via gamma radiation since the low melting point of the material would cause them to be destroyed in an autoclave.
I'm wondering how similar that is to the UV germicidal lights used in labs and such -- e.g. in a flow cabinet when not in use.
Germicidal lamps obviously couldn't be used to sterilize grains, but I'm wondering if they can be used to resterilize plastic petri dishes, or even liquid cultures (removing the issue of caramelizing sugars that people often bring up). How effective would it be against mold spores and non-bacterial/viral contaminants?
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Proud supporter of the canning jar industry.
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LizardWizard
GnomeGrower




Registered: 01/07/15
Posts: 13,688
Loc: the parking lot
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Re: Germicidal UV lights [Re: archivist]
#24724023 - 10/20/17 08:52 AM (6 years, 3 months ago) |
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Very old thread, still reviving it since I'm wondering the same, maybe today's cultivators have some new info on hand? I can't imagine there not being any of us using these in their workplace, so if you do use them or have used them, do you think it would be possible to reuse petri plates using these lamps, possibly in combination with a bleach rinse. What I was thinking of was building an enclosed box for this purpose, so the light doesn't get out (for those of you who don't know, this kind of light is very dangerous to your health, both for skin and eyes, and it's carcinogenic.)
-------------------- The best things in life can be smelled on one's fingers.
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bodhisatta 
Smurf real estate agent


Registered: 04/30/13
Posts: 61,889
Loc: Milky way
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UV-c lights are not widely used even in industry. They get sold to labs as cool gimmick. It does work but its pretty pointless if your technique is proper. If you see a lab with uv-c lights in their hoods they got sold on it by a cunning salesperson. Or its in a university where they need to spend all they money they receive
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LizardWizard
GnomeGrower




Registered: 01/07/15
Posts: 13,688
Loc: the parking lot
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Re: Germicidal UV lights [Re: bodhisatta]
#24724106 - 10/20/17 09:40 AM (6 years, 3 months ago) |
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Well, I understand that, but my purpose would be to reduce plastic waste by resterilizing plates. Glass ones aren't nearly as easy to work with. I know the plastic would deteriorate from the UVC as well, so it probably still wouldn't last forever, but even saving just half of the plastic I throw out in dish form would be a fair goal for a better environment.
Any idea if it would work for this purpose? I could live with only 95-99% of plates being clean, but any more than that and I would probably lose interest.
-------------------- The best things in life can be smelled on one's fingers.
Edited by LizardWizard (10/20/17 09:42 AM)
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bodhisatta 
Smurf real estate agent


Registered: 04/30/13
Posts: 61,889
Loc: Milky way
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Uv sterilization probably won't cut it for reused plastics. Maybe it will i found this
Look up UVC sterilization of polystyrene
https://www.microbiology.ubc.ca/sites/default/files/roles/drupal_ungrad/JEMI/16/JEMI16_144-147.pdf
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mushboy
modboy



Registered: 04/24/05
Posts: 32,256
Loc: where?
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Re: Germicidal UV lights [Re: bodhisatta]
#24724126 - 10/20/17 09:50 AM (6 years, 3 months ago) |
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id rather buy a ton of pp5 containers like josex.
Quote:
Josex said:

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mustangbob3
Mad Myrmecologist



Registered: 10/15/14
Posts: 1,685
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Re: Germicidal UV lights [Re: mushboy]
#24724208 - 10/20/17 10:29 AM (6 years, 3 months ago) |
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https://www.beautyhair.co.uk/products/gx4-steriliser-sterilizer-salon-equipment-tool-steriliser?variant=30388338252
you mean like with one these?
they work for surface sterilisation for tools so i would imagine petris would be fine too.
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LizardWizard
GnomeGrower




Registered: 01/07/15
Posts: 13,688
Loc: the parking lot
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Re: Germicidal UV lights [Re: bodhisatta]
#24724493 - 10/20/17 12:47 PM (6 years, 3 months ago) |
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Quote:
bodhisatta said: Uv sterilization probably won't cut it for reused plastics. Maybe it will i found this
Look up UVC sterilization of polystyrene
https://www.microbiology.ubc.ca/sites/default/files/roles/drupal_ungrad/JEMI/16/JEMI16_144-147.pdf
The intro of the study seems to imply that successful sterilization is possible as long as you sterilize lid and dish with the insides towards the lamp, and as long as the time and intensity needed are respected. And of course you shouldn't let the light pass through any other plastics or even glass probably, as to minimize any filtering of the UV rays. If you wouldn't pre-treat with bleach then it would also be best to treat both sides, and I think a matte white finish on the inside would be a pro as well, to maximize usable output.
-------------------- The best things in life can be smelled on one's fingers.
Edited by LizardWizard (10/21/17 05:43 AM)
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LizardWizard
GnomeGrower




Registered: 01/07/15
Posts: 13,688
Loc: the parking lot
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Had some more time to figure this stuff out, so here it goes.
They use 2 devices in the study, the one I'm most interested in is the Stratalinker UV crosslinker. This device has, depending on model, 5 8W TL bulbs, or 5 15W TL bulbs. I'll be ordering 2 15W bulbs.
According to the study, 10 mins at max setting in this device is enough to kill off all contaminants (provided everything is empty and surfaces appear clean, and the light is not filtered by, for instance, a plate lid, so no closed plates in there).
The lamps are around 40 cm and the inside dimensions of the Stratalinker cabinet are 47.7 W× 34.3 D × 16.8 H, all in cm, but it has 5 bulbs.
Since I'll only be using 2, I'll be going for inside dimensions of 46 B× 13 D × 16.5 H, with a little 12mm edge on the bottom in the back, so my 58mm plates can be shoved against that edge to ensure everything is getting even coverage by the light. The surface will be big enough to hold 16 plates, therefore should be able to sterilize enough plates for 1 liter of agar in 1 hour easily (calculated at 200 ml/16 plates, so 5 runs, with 2,5 minutes to get the plates in front of the hood and loading new ones, should be enough...) It's actually half, forgot to count 2 spaces for 1 dish (lid and dish)
-------------------- The best things in life can be smelled on one's fingers.
Edited by LizardWizard (10/21/17 07:04 AM)
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potnug



Registered: 07/06/17
Posts: 321
Last seen: 4 years, 6 months
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https://micro.cornell.edu/research/epulopiscium/bacterial-endospores
"Endospores can survive environmental assaults that would normally kill the bacterium. These stresses include high temperature, high UV irradiation, desiccation, chemical damage and enzymatic destruction."
http://www.austincc.edu/microbio/2421c/ec.htm
The first sentence of this paper says E. coli is non-spore forming, and E. coli is what was used in that paper bod brought up
I don't think UV would work for us
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LizardWizard
GnomeGrower




Registered: 01/07/15
Posts: 13,688
Loc: the parking lot
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Re: Germicidal UV lights [Re: potnug]
#24726508 - 10/21/17 08:46 AM (6 years, 3 months ago) |
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Endospores aren't spores, just FYI.
-------------------- The best things in life can be smelled on one's fingers.
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Mad Season
hookers and blackjack



Registered: 09/16/12
Posts: 12,666
Loc: Canada
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They're not spores. They're fuckin monsters.
Better shield your kids eyes or they'll get nightmares.
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LizardWizard
GnomeGrower




Registered: 01/07/15
Posts: 13,688
Loc: the parking lot
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Re: Germicidal UV lights [Re: Mad Season]
#24726556 - 10/21/17 09:22 AM (6 years, 3 months ago) |
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Same for the lamp.
-------------------- The best things in life can be smelled on one's fingers.
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Mad Season
hookers and blackjack



Registered: 09/16/12
Posts: 12,666
Loc: Canada
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tis true.
Also crazy you're up to 3k posts now xD
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LizardWizard
GnomeGrower




Registered: 01/07/15
Posts: 13,688
Loc: the parking lot
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Re: Germicidal UV lights [Re: Mad Season]
#24726905 - 10/21/17 11:58 AM (6 years, 3 months ago) |
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I know 
I think the endospores are a non-existent problem. Endospores only form when bacteria have no source of food. The bacteria will have a source of food until the plate is emptied and subsequently sprayed with a 10% bleach solution acidified back to 6,5 to maximize efficiency, then they will be dropped in water to rinse off the bleach, then dried and into the cabinet. This leaves virtually no space or time for any possible bacteria to form endospores. I think a 95% succes rate would be easily achieved. I'll do a test once I get everything in of course. If any endospores are still present and viable, then they should show up after a few days, or in the next receiving plate.
-------------------- The best things in life can be smelled on one's fingers.
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LizardWizard
GnomeGrower




Registered: 01/07/15
Posts: 13,688
Loc: the parking lot
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I'll do a baby motorboat sound in front of an opened plate now, so I have a bacterial plate to test this out with. Maybe I'll fart on one too.
-------------------- The best things in life can be smelled on one's fingers.
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LizardWizard
GnomeGrower




Registered: 01/07/15
Posts: 13,688
Loc: the parking lot
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Re: Germicidal UV lights [Re: Mad Season]
#24727463 - 10/21/17 04:58 PM (6 years, 3 months ago) |
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BTW, just noticed YOU are the one who helped me improve my agar techniques. Didn't know it was you who wrote the "improve your sterile technique" thread. Thanks for that! Got a lot of use out of it a while back!
-------------------- The best things in life can be smelled on one's fingers.
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mustangbob3
Mad Myrmecologist



Registered: 10/15/14
Posts: 1,685
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have you ever thought about one of these?
https://www.philips.co.uk/c-p/SCF274_31/avent-electric-steam-steriliser
only takes 8 mins.
i use for tweezers, scalpels ect just not sure how you will take the petris out and remain 100% sterile as they will have to be in halfs to surface sterilize.
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LizardWizard
GnomeGrower




Registered: 01/07/15
Posts: 13,688
Loc: the parking lot
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Quote:
mustangbob3 said: just not sure how you will take the petris out
How about molten?
-------------------- The best things in life can be smelled on one's fingers.
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mustangbob3
Mad Myrmecologist



Registered: 10/15/14
Posts: 1,685
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yeah was late
wasnt thinking
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