[extropy-chat] Resources for microscopes

[Robert Bradbury]

The problem with agar is that it can get quite expensive if you want
quantities of it (though you don't need much to make up a plate full) --
microbiologists can go through lots of plates quite quickly.

I've been thinking about how one could use common household materials for
this type of work.  Plastic coffee can lids come to mind but they aren't as
deep or as clear as normal plates (its sometimes useful to look at plates
with a light behind them if one wants to pick off individual colonies).  I
know from a recent experiment done in my fridge hat you can grow fungi on
jello, but I think it has too high a sugar concentration for "common"
bacteria.  Anyone have any ideas for a low glucose concentration substrate?
Jello+flour+some fiber mix? Though this too suffers from the lack of
transparency problem.  Actually, since most bacterial colonies tend to be
white one might be able to add food coloring to get around this problem.

Here is an experiment I'd like some people to try...  We have all heard the
"classical" comment that bacteria replicate in 20 minutes.  One measures
this by growing a "large" quantity in replication phase and taking samples
at periodic intervals (hours/days) and doing dilutions 1:10, 1:100, etc.
until one can plate a small sample on a plate and do colony counts to
determine growth rate.  I'd love to know the ideal mix and conditions for
maximal bacterial growth using materials commonly found at home.  (One
question would be how much one could "juice" the growth rate by using an
aquarium pump to bubble air through the medium -- or think up another way to
"mix" it -- though if one wants to grow anaerobic bacteria one wants to
deplete the air.)

Another good source for bacteria is garden soil or a compost heap, esp. at
the top where the O2 concentration is relatively high.

Robert
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