for example, by oxidation of ammonia to nitrite or a mitrite to nitrate (by nitrifying bacteria), or oxidation of hydrogen sulfide to sulfur(by colorless sulfur bacteria).

• 例如把氨氧化为亚硝酸盐或硝酸盐（通过硝化细菌），或把硫化氢氧化为硫（通过无色的硫细菌）。