Does yeast need sugar to survive?
Depending on the instructions on the package, you may or may not need to add sugar along with water. Some yeasts already have sugars mixed in, while others don’t. Instant yeast and active dry yeast do not have sugar mixed in because you put them in doughs and batters, which have sugars. However, just adding water would not be sufficient for its growth. Fresh yeast has sugars mixed in and you would only need to add water for the yeast to grow on its own. Keep in mind that yeast needs much more than sugar to survive (the five major compounds are hydrogen, sulfur, carbon, oxygen, nitrogen, phosphorus). So an unsuccessful culture could be due to a lack of compounds other than sugar.
