Hydrogen powers important nitrogen-transforming bacteria

Nitrite-oxidizing bacteria are key players in the natural nitrogen cycle on Earth and in biological wastewater treatment plants. For decades, these specialist bacteria were thought to depend on nitrite as their source of energy. An international team of scientists led by Holger Daims, a microbiologist at the University of Vienna, has now shown that nitrite-oxidizing bacteria can use hydrogen as an alternative source of energy. The oxidation of hydrogen with oxygen enables their growth independent of nitrite and a lifestyle outside the nitrogen cycle. The study is published in the current issue of the journal "Science". Nitrogen, an essential chemical element for life, is transformed into its different chemical forms in numerous steps of the global nitrogen cycle. Nitrite-oxidizing bacteria are important players in nitrogen cycling since they convert the toxic nitrite to the less harmful nitrate. "Humans exploit this process in biological wastewater treatment. Moreover, the formed nitrate is a substrate for other important microbial processes and a source of nitrogen for many plants" explains Hanna Koch, first author of the study and Ph.D. student at the Department of Microbiology and Ecosystem Science of the University of Vienna. Since the description of the first nitrite-oxidizing bacteria in the 19th century, scientists have assumed that the survival of these microorganisms would depend on nitrite as their source of energy. Therefore, the presence of nitrite-oxidizing bacteria in the environment and in wastewater treatment plants has commonly been associated with the nitrogen cycle. Nitrospira: Nitrite oxidizers with surprising features