Both. Some people use primarily bacterially-dominated teas for vegetative growth and fungi-dominated teas for flowering.
It's generally easier to brew teas dominated by bacteria. Bacteria proliferate rapidly, utilizing simple sugars as a food source, like the sugars in molasses (glucose, fructose, sucrose). Where ever you have mostly simple sugars in a substrate, bacteria are going to dominate that substrate.
Fungi take longer to grow in teas. They break down starches, cellulose, chitin, and other complex compounds such as lignin. Most bacteria lack the enzymes required to break down the more complex substances in organic matter. Many varieties of fungi engage themselves in symbiotic relationships with plant roots, where they exchange water and nutrients for energy. These kinds of fungi among others possess enzymes which allow them to break away phosphates otherwise caught up in heavily-bound complexes in the soil.
