Alternative to Autoclave??

Hiranya Roychowdhury hroychow at NMSU.EDU
Mon Nov 24 11:21:13 EST 1997

At 01:48 PM 11/23/97 GMT, Robert A. wrote:
>The question stems from my interest/activity as a beer brewer.  I
>currently culture and store various ale and lager yeast samples for
>use in my brewing.  With my current methods, I am able to store yeast
>cultures for about 8 weeks.  So far, I am doing simple sterile water
>"washing" and have experimented with freezing yeast in a glycerin
>My desire is to store yeast cultures on agar "slants".  I am less than
>a novice in microbiology, but I don't see any major problems with
>methodology,  my concern is with "autoclaving".
>Is there an acceptable alternative to autoclaving.... i.e. 60 minutes
>in a hot oven??  Will treatment in an oven be effective in sterilizing
>slant tubes that would house yeast cultures in a refridgerator for 6
>months?  A year?.
>Would sterilizing agar in this manner work?
>Any insight would be greatly appreciated.  I don't have the funds to
>invest in an autoclave.
>Robert A.

Sterilizing in a hot oven may or may not work depending on the organism one
is trying to kill. Dry heat, for a prolonged period (1 or 2 days) will kill
regular cells but may spare most endospores. Treating the dry stuff
(glasswares, metals etc) in 60-70% ethanol for 15 min and then putting them
in a 80 C oven for 24 h may do the trick. Agar can't be sterilized with dry
heat. You need high pressured "wet" heat for that. If you are working out of
your home, I am sure you will have access to a pressure cooker. You can
pretty much sterilize everything in one of those. In fact, lot of labs use
them when a large autoclave is not necessary. Thirty to forty minutes in a
pressure cooker is all that is needed to sterilize.

Dr. Hiranya Sankar Roychowdhury
Plant Genetic Engineering Lab.
New Mexico State University
Las Cruces, NM 88003
Ph. (505) 646-5785
hroychow at

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