 Scientists are researching the use of algae to produce liquid fuels, and bacteria to convert various forms of agricultural and urban waste into usable fuels.Microorganisms are used to produce many commercial and industrial chemicals, enzymes and other bioactive molecules.Organic acids produced on a large industrial scale by microbial fermentation include acetic acid produced by acetic acid bacteria such as "Acetobacter aceti", butyric acid made by the bacterium "Clostridium butyricum", lactic acid made by "Lactobacillus" and other lactic acid bacteria, and citric acid produced by the mould fungus "Aspergillus niger".