Asked by: Anonymous
Bacteria evolved in environments where the concentration of sugars and salts is the same as or lower than those inside the cell.
High sugar concentrations cause the bacterium to lose water by osmosis and it doesn’t have any cellular machinery to pump it back in against the osmotic gradient. Without enough water, the bacteria can’t grow or divide.
Mould is more tolerant though and can grow on some jams.
Read more:
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
