The meaning of is an anaerobic, is a process without O2 or anaerobic respiration. Anaerobic organisms (bacteria) do not use O2 in their process and can die by O2. Anaerobic organisms disseminate carbohydrates so that glucose can convert into ethanol (alcohol) and carbon dioxide. This process is called fermentation. Useful for biogas in anaerobic treatment systems, but disastrous for cultivation water. Many unwanted bacteria are anaerobic bacteria and harmful in cultivation.