In the secondary treatment of waste, flocs are used which are a mesh formed due to the association of fungal filament with the aerobic bacteria. These flocs for sediments are the treatment called as activated sludge. This sludge can be said to be rich with aerobic bacteria as it is formed of flocs. This activated sludge is later used in anaerobic sludge digestor. Methanogens present in stomach of ruminants and biogas plants are anaerobic bacteria. Mushrooms and truffles are fungi