We don't have an incubator at school here. I was wondering how other people go about incubating agar plates etc.? Most pracs seem to ask for incubation at 37 degrees. Does any one have success with growth on plates just left out at room temperature? Is there a cheaper alternative to buying an incubator, from looking at catalogues, they seem to cost a lot, or has some one come across a small cheap one?
Thanks
Pilar
incubators
Re: incubators
We use the incubator mainly for senior biology, for the junior pracs we place the sealed plates on trays and leave by the window ledges in the sun. We mainly get fungal growths which occur in about 1 week.
Re: incubators
Hi there,
We have a litlle hot water cylinder in a cupboard under one of my prep. room sinks which sits at about 25 degrees. This does the job nicely, more than enough growth for the students and from a safety perspective you aren't encouraging human pathogens. They will still grow but you aren't selecting an optimal temperature for them and there growth is inhibited. (in a previous life I worked in pathology labs). If you have something similar it might be worth a try.
Regards Trudy
We have a litlle hot water cylinder in a cupboard under one of my prep. room sinks which sits at about 25 degrees. This does the job nicely, more than enough growth for the students and from a safety perspective you aren't encouraging human pathogens. They will still grow but you aren't selecting an optimal temperature for them and there growth is inhibited. (in a previous life I worked in pathology labs). If you have something similar it might be worth a try.
Regards Trudy
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Ocean Breeze
- Posts: 798
- Joined: 01 Jun 2006, 10:00
- Job Title: Lab Manager
- State/Location: NSW
Re: incubators
Yes indeed.
We have one U-Beaut incubator, that thermostats to 0.1 of a degree C.
So I can control anywhere from room temperature to 65 deg C.
However, there are pracs that require effect of temperature variations on growth, or enzyme pracs that similarly require various temeratures for comparasin.
I have a number of polystyrene eskies set aside for that purpose.
I punched 2 holes in the side, big enough to feed electrical wires through. The holes should be about 3/4 way down the side- not on the bottom as I didnt want any spilled liquid to pool near the wires. I set up a regular power power pack (0-12V)... like the ones we use for the students in the lab....outside the esky.
I Use a small incandescent globe on a stand(again like the ones the kids use for their electricity pracs) inside the eskie. This is taped to the inside near the wire inlets. Use a decent tape, like packing, masking... one thats less likely to be affected by heat and melt the glue.
Now pack underneath and around the side the globe (where it may touch or heat the polystyrene) with double aluminium foil to insulate. Ensure that the whole thing looks safe!
Next, secure a double piece of Al foil from side to side in the esky, about 2-3" away from the globe. Make sure that theres a free air space under the foil (ie that is several inches off the bottom) and similar clearance at the top. The idea behin d this is that we are then allowing for convection currents within the unit, while shielding the plates from direct heat from the globe(which may melt the agar as well as disturb the required temperature). This allows for even temperature distibution due to the convection.
Next, we make a small hole in the esky lid, through which we feed a 0-100 deg C thermometer. Make sure that the thermometer is supended securely in the most appropriate spot, and not touching any of the agar plates that will be put in later. That most likely will on the side away from the globe, and in the path of the air flow. Sometimes thermometers come with small rubber securing rings, or failing that, can be taped in place.
You will need to trial your temperatures the day before you need to use it for plates.
Adjusting the voltage knob on the power pack will then vary the brightness, and therefore the heat that is given off by the globe. This is now your manual thermostatic control.
The secondary way to fine tune our temperature , is that we can lift the lid at one end by a tiny fraction. A lot depends on the external room temperature to start with, that is why trialing before the actual day is essential. The little holes where the wires enter, provide a small amount of fresh air, and ensure that the plates are aerobic, and prevent anerobic growths.
Your agar plates are then stacked on a small wire grid in the bottom of the esky, on the opposite side from the globe.
I make a point of never incubating micro-organisms at 37 deg C.. as this is likely to select for pathogens! Enzyme pracs are ok.I do mine at 34 max, if they ask me for the 37 deg C, despite the fact that the teachers may ask for the 37 deg C, as it is written this way in some pracs.
MAKE SURE THAT AS FAR AS POSSIBLE, YOU USE THESE ESKY SET UPS FOR THE LOWER TEMPS.
That way I can use different eskies for different temperatures, and I use my "real" incubator for the higher temps.
I also use the fridge coils to heat.Check out the temperature of the air rising from the coils.Often its enought to grow general, junior micro-organisms.
I put my agar plates on a wire rack, over the top-back of the fridge. Make sure that you place a counterbalance weight on the front of the rack to prevent it toppling.
Then lie back and relax and enjoy
We have one U-Beaut incubator, that thermostats to 0.1 of a degree C.
So I can control anywhere from room temperature to 65 deg C.
However, there are pracs that require effect of temperature variations on growth, or enzyme pracs that similarly require various temeratures for comparasin.
I have a number of polystyrene eskies set aside for that purpose.
I punched 2 holes in the side, big enough to feed electrical wires through. The holes should be about 3/4 way down the side- not on the bottom as I didnt want any spilled liquid to pool near the wires. I set up a regular power power pack (0-12V)... like the ones we use for the students in the lab....outside the esky.
I Use a small incandescent globe on a stand(again like the ones the kids use for their electricity pracs) inside the eskie. This is taped to the inside near the wire inlets. Use a decent tape, like packing, masking... one thats less likely to be affected by heat and melt the glue.
Now pack underneath and around the side the globe (where it may touch or heat the polystyrene) with double aluminium foil to insulate. Ensure that the whole thing looks safe!
Next, secure a double piece of Al foil from side to side in the esky, about 2-3" away from the globe. Make sure that theres a free air space under the foil (ie that is several inches off the bottom) and similar clearance at the top. The idea behin d this is that we are then allowing for convection currents within the unit, while shielding the plates from direct heat from the globe(which may melt the agar as well as disturb the required temperature). This allows for even temperature distibution due to the convection.
Next, we make a small hole in the esky lid, through which we feed a 0-100 deg C thermometer. Make sure that the thermometer is supended securely in the most appropriate spot, and not touching any of the agar plates that will be put in later. That most likely will on the side away from the globe, and in the path of the air flow. Sometimes thermometers come with small rubber securing rings, or failing that, can be taped in place.
You will need to trial your temperatures the day before you need to use it for plates.
Adjusting the voltage knob on the power pack will then vary the brightness, and therefore the heat that is given off by the globe. This is now your manual thermostatic control.
The secondary way to fine tune our temperature , is that we can lift the lid at one end by a tiny fraction. A lot depends on the external room temperature to start with, that is why trialing before the actual day is essential. The little holes where the wires enter, provide a small amount of fresh air, and ensure that the plates are aerobic, and prevent anerobic growths.
Your agar plates are then stacked on a small wire grid in the bottom of the esky, on the opposite side from the globe.
I make a point of never incubating micro-organisms at 37 deg C.. as this is likely to select for pathogens! Enzyme pracs are ok.I do mine at 34 max, if they ask me for the 37 deg C, despite the fact that the teachers may ask for the 37 deg C, as it is written this way in some pracs.
MAKE SURE THAT AS FAR AS POSSIBLE, YOU USE THESE ESKY SET UPS FOR THE LOWER TEMPS.
That way I can use different eskies for different temperatures, and I use my "real" incubator for the higher temps.
I also use the fridge coils to heat.Check out the temperature of the air rising from the coils.Often its enought to grow general, junior micro-organisms.
I put my agar plates on a wire rack, over the top-back of the fridge. Make sure that you place a counterbalance weight on the front of the rack to prevent it toppling.
Then lie back and relax and enjoy
-
pkij
- Posts: 119
- Joined: 10 Aug 2006, 10:00
- Job Title: Lab Tech
- School: Good Shepherd Catholic College
- Suburb: Mount Isa
- State/Location: QLD
Re: incubators
Wow thanks rainbow sky 
, I will attempt to construct the "incubator", will be a lot cheaper than buying one for the small amount it would get used at the moment. I knew someone would be come up with ideas, how you ever thought of it, you are a marvel. It gets quite hot here in Mount Isa so we don't need too much heating up, but it is good to be able to control the temp for some pracs.
Thank goodness for this site
, I will attempt to construct the "incubator", will be a lot cheaper than buying one for the small amount it would get used at the moment. I knew someone would be come up with ideas, how you ever thought of it, you are a marvel. It gets quite hot here in Mount Isa so we don't need too much heating up, but it is good to be able to control the temp for some pracs.Thank goodness for this site
