Conference on nitrification draws international experts

Tom Garlinghouse ・ For the High Meadows Environmental Institute

Princeton’s department of geosciences recently hosted the eighth International Conference on Nitrification and Related Processes (ICoN8). The five-day event, held from July 30 to August 3 of this year, brought together scientists and researchers from all over the world to discuss and share current research on nitrification and related processes in the nitrogen cycle.

“The conference is held every two years,” said Bess Ward, the William J. Sinclair Professor of Geosciences and the High Meadows Environmental Institute at Princeton University. “Its purpose is to update participants on the latest developments in the study of nitrification, and encourage interaction and collaboration at the cutting-edge of the field.”

Nitrification is an essential process of the biochemical nitrogen cycle. The nitrogen cycle is indispensable to life on this planet and involves the processes whereby nitrogen moves from the atmosphere to Earth, through water and soils and back to the atmosphere in an endless cycle. Nitrification occurs in soils when ammonium (NH4) is oxidized to nitrite (NO2) and then to nitrate (NO3). It is carried out by diverse microbes, usually in the presence of oxygen, in both aquatic and terrestrial ecosystems.

Nitrogen is commercially important as a fertilizer but is also a major element in wastewater treatment systems, said Ward. In the case of plants, nitrate is an essential nutrient that is involved in plant growth, development and metabolism. But too much nitrate can cause problems. Excess nitrate from fertilizers can accumulate in soils and ground water and can run off into lakes, streams and the ocean. This runoff can cause severe environmental problems, such as algae blooms that are detrimental to many aquatic organisms and cause a deterioration in overall water quality.

Nitrogen in the form of ammonium also accumulates in wastewater and one of the primary tasks of wastewater treatment facilities is the removal of ammonium via biological processes – in other words, oxidation to nitrite and nitrate by nitrifying microbes. As is the case with agricultural runoff, discharge of incompletely treated wastewater will cause excess algae growth in rivers and streams.

Approximately 150 people attended this year’s event, which was held in the atrium and commons of Princeton’s Frick Chemistry Laboratory. Attendees included experts and researchers from many different fields, including oceanography, engineering, biology, biochemistry, and ecology, among others. The conference included researchers who have been attending the meetings for many years, but also, Ward said, a large group of students and a number of people, especially the invited speakers, who had only attended previous events sporadically or had never attended.

“These were people I had long been wanting to recruit,” Ward said, “so I was pleased they came and got involved.”

The conference began on Sunday, July 30, with a breakfast followed by an all-day early career and graduate student workshop, which emphasized the possibility of careers, in academia, industry and elsewhere, for those studying the nitrogen process. This concluded in the evening by the opening plenary speaker, Holger Daims, Professor, Deputy Head of the Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, who gave a talk entitled, “An expanded picture of nitrification: Comammox, alternative lifestyles and microbial interactions.”

The bulk of the conference, however, consisted of six sessions, each initiated by an invited speaker. These speakers included experts from far afield as Germany, Austria, Japan, the United States and South Korea. These talks were typically between one half hour and forty-five minutes in length and emphasized many different aspects of nitrification, from questions involving biochemistry and bioenergetics to biotechnology and issues in soils and agriculture.

“Our sessions covered everything from fundamental science — such as the biochemistry of how organisms and enzymes work — to applied systems such as bioengineering and wastewater treatment plants,” said Ward.

One talk even explored the thorny dynamics between nitrification and climate change. Given by Emily Zakem, principal investigator at the Carnegie Institution for Science California, in Pasadena, California, it focused on understanding and predicting nitrification under the threat of global warming resulting from climate change. Another talk looked at some of the potential solutions for mitigating the damage to ecosystems, such as waterways, caused by excess nitrate generation in agriculture. This talk was given by Gunter Subbarao, senior scientist and group leader for BNI Research, Japan International Research Center for Agricultural Sciences in Tsukuba, Japan.

Each invited talk was accompanied by six or eight shorter-length talks given by researchers from various academic and industry backgrounds.

The conference also consisted of two formal poster sessions, but the posters — a total of 80 in all — were up the entire conference. “We left the posters up the whole time,” Ward said, “so that in-between every break, at all the meals, and after the meetings, people could view them. This was where a lot of intense exchange and discussion actually happened.”

The closing plenary talk was given by Sukhwan Yoon, professor in the department of civil and environmental engineering, Korea Advanced Institute Science and Technology in Daejeon‎, ‎South Korea. It focused on recent attempts using microbial organisms to mitigate the generation of nitrous oxide (N2O) in wastewater and agricultural soils.

The first ICoN conference began in 2005 soon after a team of researchers, including Bess Ward, were able to sequence the genome of several nitrifying bacteria. This was a major breakthrough that succeeded in bringing together many scientists who had formerly been working on the process of nitrification separately. This collaboration subsequently led to a book — a collection of scientific papers on nitrification, edited by Ward — and also the first ICoN conference, which was held in Louisville, Kentucky.

“The conference moves back and forth between the United States, Europe and Asia,” said Ward.

Ward emphasized that the concept of nitrification is not solely an academic subject, but should be of interest — and concern — to the general public.

“The process of nitrification is especially important in agriculture and wastewater treatment systems — two areas of life that affect everyone,” said Ward.

“The other thing that is of utmost importance now is that nitrification is a major source of nitrous oxide in many parts of the ocean and in some soils,” Ward added. “And nitrous oxide is a very potent greenhouse gas.”

The ninth International Conference on Nitrification and Related Processes will be held 2025 in Bremen, Germany.