Based on the capabilities of Earth microbes, the usually cited lowest temperature for life is-20�C . However, there is indirect evidence of continuing bacterial activity in glaciers down to-40�C, at a very low metabolic rate of ten turnovers of cellular carbon per billion years.
32.
Changes in pH and concentrations of urea, ammonium, calcium and calcium carbonate in pore fluid with the distance from the injection point in 5-meter column experiments have shown that bacterial activity resulted in successful hydrolysis of urea, increase in pH and precipitation of calcite.
33.
In the southern part of Europe, where panettone was originally made with sourdough, sourdough has become less common in recent times; it has been replaced by the faster-growing baker's yeast, sometimes supplemented with longer fermentation rests to allow for some bacterial activity to build flavor.
34.
However, " the variety of differences indicates a probable chemical or biochemical reaction on the hair . " Compounds Responsible for the Odor of Dog Hair Coat This appears to suggest that an increase in bacterial activity is a likely culprit . talk ) 05 : 20, 7 March 2008 ( UTC)
