New answers tagged microbiology
Sugar participate in food preservation only at high concentrations. When microbes are introduced to high sugar concentrated environment, water inside the microbial cell diffuses out to the high sugar concentrated solute due to the phenomenon called osmosis. As water is very much needed for cell functioning and metabolism the dehydrated cells fail to perform ...
In short our environment always tries to maintain an equilibrium, a stable state. When microbes encounter a surrounding like a high concentrated sugar state or solution (hypertonic), water diffuses out of the permeable cellular membrane of the microbe to its outer environment with high sugar concentration causing dehydration of the microbe and it leads to ...
In (very) short: enzymes are necessary for life. Cytoplasm is necessary for enzymes to function. Water is necessary for cytoplasm to exist. Cells have osmotic membranes. Given a cell in a solution (even a goopy one, like jam) with a very high concentration of sugar, water will move along a gradient of low to high sugar concentration, in other words, water ...
Actually, it doesn't kill them. As far as I am aware people with weak immune responses shouldn't eat honey or jams because of risk of fungal or bacterial infections. Resource: http://www.mayoclinic.org/drugs-supplements/honey/evidence/hrb-20059618
Bacteria effectively clone themselves so theoretically all clones are identical. However like every organism they're subject to Darwinian evolution so there's always a chance a random mutation happens. Since bacteria usually reproduce fast the rate of these mutations can happen fast resulting in the strain evolving to a (slightly) different strain.
In theory they're clones, but depending on the age of the strain(some strains are surprisingly old: ~40 years) there's variation inside strains. The reverse is also true. Bacteria from a single species are isolated twice and named different things by different labs and the mistake can take years to even find, much less correct.
While I believe that it is possible to keep a bacterial culture viable while frozen in glycerol stock at around -20 °C, as attested to by WYSIWYG, it is important to note that your "typical household freezer" may not be suitable for such a purpose. This is because household freezers usually have an "auto-defrost" function. This makes it temporarily thaw ...
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