Marga asked what would be the legal limit of yeast and bacteria cells in red wine, white wine and fortified wine.
To my knowledge there is no legal limit on yeast or bacteria cells in the United States. I cannot speak for other countries but have never heard of such limitations. The truth is, if you have an inordinate amount of yeast or bacteria in a wine it will not taste good and will spoil easily, making it commercially unacceptable. One thing I would like to note is that there is no bacteria harmful to humans that can live in wine. Therefore, any bacteria in a wine would cause other types of spoilage problems such as vinegar or acetic acid. This is one of the worst bacteria forms that can invade wine and ruin it, yet humans consume it in other products all the time.
In the United States, there are 2 primary restrictions or limits regarding wine production. The legal limit of volatile acidity (read vinegar bacteria) is .12 grams per 100 milliliters in white wine and .14 grams per 100 milliliters for red wine. The legal limit of sulfites in any wine cannot be over 300 parts per million.