Although there are many types of microorganisms related to metal corrosion, the more important ones are the microorganisms that directly participate in the sulfur, iron and nitrogen cycles in nature. Participating in the sulfur cycle are sulfur-oxidizing bacteria and sulfate-reducing bacteria; participating in the iron cycle are iron-oxidizing bacteria and iron bacteria; participating in the nitrogen cycle are mainly nitrifying bacteria and denitrifying bacteria. These bacteria can be divided into two categories: aerobic corrosive bacteria and anaerobic corrosive bacteria according to their requirements for oxygen during growth and development. Nitrifying bacteria, such as Nitrosomonas and Nitrobacter, can oxidize ammonia into nitrite, and then further oxidize it into nitric acid, while obtaining energy for their own survival. Denitrifying bacteria, such as Pseudomonas denitrificans, Pseudomonas stutzeri, Cpromobacterium vio-laceum, etc., can reduce nitric acid to nitrate in a poorly ventilated environment. Nitric acid. Therefore, this type of bacteria can accumulate a certain amount of nitric acid and nitrite in the environment, thereby causing corrosion to metals.
Another study found that a type of mold, Cladosporium resinae, can corrode aluminum alloys in a short period of time.