h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Hi,
I worked in a research lab where I used yeast as part of my project. There are a couple of things I learned:
the ideal temperature for yeast to grow is between 25 and 35 degrees Celsius. It grows more slowly at lower temperature (it keeps growing in the fridge - about 4-8 degrees but oh so slowly) and higher temperatures (up to 42 degrees is fine, but it is a stressful environment). So it depends on the kind of bread you're making. The most important thing is to keep it at a constant temperature, no drafts basically, to have more predictable results.
Sugar - it is true, yeast does not need sugar to grow; some strains though are slow starters, and adding some sugar helps them grow better, especially if the amount of yeast is very low.
Hope this helps. I've to go, I am experimenting a new bread today and I don't want to make it burn in the oven!!!

Interesting to be assured that sugar isn't necessary, as I've always had excellent results in bread-making if I begin by making a paste of fresh yeast and an equivalent volume of sugar. It's interesting to watch: it begins as a stiff spiky goo, then generates liquid and collapses into a sloppy mush. The smell is quite attractive and malty, and if a fingertip is dipped in and then tasted it's also got a uniquely different sweet taste. Diluted in a little warm water and left to stand, it begins to generate a scum and a lot of gas (carbon dioxide?). Leave it to stand, and five minutes later, it can be tipped into the oil/salt/flour to carry on the good work there, with the last clinging-to-the-containere dregs swilled round in warm water and added as needed. I've always found this gives magnificent light doughs and really good bread