Next in size come the fungi. Fungi have smaller appetites since they have about 100 times larger body size and anaerobic bacteria have poor appetites due to the unavailability of oxygen. If bacteria, fungi, and worms are competing for food in a worm bin, obviously bacteria would win due to their speed of food consumption and growth. Given ideal conditions of temperature, moisture, pH and aeration, bacteria can double their population in 20 minutes, fungi in 3-4 hours, while worms take days. This speed of reproduction coupled with their voracious appetite mentioned above make beneficial bacteria the clear winner if conditions are suitable for them.
Fungi come into play only when bacteria slow down due to low moisture or acidity.
Stale bread, for example, would develop fungal growth when the moisture level is too low for bacteria. Composting starts with bacteria but it will soon change over to fungal mode due to the acidity produced by the bacteria. Thus, redworms have a role when the pH becomes acidic and bacteria slow down their activity. It is found that redworms grow faster and eat fastest when the pH is around 5. Redworms consume the acidic food and produce alkaline excretions, thus shifting the pH to neutral, which is more suitable for bacteria.