Thread: How much heat is needed to kill a bacteria?

I mean this is a broad broad broad question, i know.
I'm just wondering, some bacteria needs like more than 100c to kill and be at that temperature for a few minutes. Then how is it that by flaming the culture bottle top we assume that we sterilise them?

Very few bacteria are not killed quickly at 100c.

depends on wat bacteria

It is called incineration. Burns any organism to ash.

Generally speaking, sterilization involves heating at high temperature (about or above 120C), under vacum for 30min-1hour. This will kill ALL bacteria which may contaminate, say, your glassware in the lab. For some procedures, however, like when you are spreading bacteria onto Agar plates, when you are setting up a bacterial culture and so on, a quick "zap" at the methane flame - which is very hot, by the way - is enough to block unwanted bugs to contaminate your samples (which happen to be already sterile). This is mostly because the marker of selection in your medium will kill the bacteria which do not present this marker (amp resistance, for example). So, you can stop contamination of already autoclaved media with the flame, but you can kill those present, if any.
I would not work just close to a flame (without the use of a hood) when you want to work in sterile conditions for long term, like when you want to keep cell lines in culture

its 121c alllllllll microbes willllll be killed but not thermophilic bacteria those live in that temperature

For practical purposes Lovely Green Eyes is correct, and that's the standard that is used in the lab. However, the next answer is also correct in that there are thermophillic bacterium that live at very extreme temperatures. Many of these are collected and studied from Yellowstone and some are collected from heat vents in the ocean.

So for theoretical purposes, the temp of 120C is not sufficient for ALL bacteria. I'm not sure enough study has been undertaken to really know what is required for killing the extreme thermophiles. Some thought says they can withstand temperatures up to 130C, but the prevailing thought is that nothing would survive a temperature over 150C