A biological indicator used in autoclaving is a vial containing 10^9 Geobacillus stearothermophilus cels that is placed in the autoclave with the material to be sterilized. After autoclaving the vial is incubated and examined for growth. Why is this species used as opposed to E.coli or G. subtilis?
2007-07-10 23:22:55 · 2 answers · asked by Hiroshi 2 in Science & Mathematics ➔ Biology
Guess. It sounds like the organism you mention is an extreemophile. These bacteria are capable of withstanding much more heat than E. coli or B. subtilis (never heard of G. subtilis). Thus the use of this organism as an indicator is a more stringent test to ensure complete killing in an autoclave run.
2007-07-11 00:57:28 · answer #1 · answered by michaelhobbsphd 3 · 0⤊ 0⤋
Dr. Hobbs is right - just to complete his answer: if the thermophilic bacteria are dead after the run, then the autoclave got hot enough to sterilize whatever was in it. Escherischi and Bacillus die at heat levels lower than that needed to completely whack nasty viruses and other biohazardous microbial odds and ends. If they're dead, that still doesn't tell you that the autoclave got hot enough. I'm assuming, by the way, that you mean B. subtilis. I'm not familiar with any G. subtilis.
2007-07-11 02:31:05 · answer #2 · answered by John R 7 · 0⤊ 0⤋