User:Legare.katie/sandbox

- I added a photo of Pseudomonas stutzeri to the page

-In general, denitrifying bacteria prefer slightly soil with a more alkaline pH, and they are more sensitive to an acidic pH than most bacteria. (Valera)

Valera, C.L., Alexander, M. Nutrition and physiology of denitrifying bacteria. Plant Soil 15, 268–280 (1961).

Ideas:

-write about use of denitrifying bacteria in respect to wastewater (https://www.sciencedirect.com/science/article/abs/pii/S004313549600228X)

-anaerobic denitrification of methane (https://www.pnas.org/content/111/51/18273)

Final Work:

Role of denitrifying bacteria as a methane sink

Denitrifying bacteria have been found to play a significant role in the oxidation of methane (CH4) (where methane is converted to CO2, water, and energy) in deep freshwater bodies of water.1 This is important because methane is the second most significant anthropogenic greenhouse gas, with a global warming potential 25 times more potent than that of carbon dioxide,2 and freshwaters are a major contributor of global methane emsions.1

A study conducted on Europe’s Lake Constance found that anaerobic methane oxidation coupled to denitrification - also referred to as nitrate/nitrite-dependent anaerobic methane oxidation (n-damo) - is a dominant sink of methane in deep lakes. For a long time, it was believed that the mitigation of methane emissions was only due to aerobic methanotrophic bacteria (include link to methanotrophs wiki page). However, methane oxidation also takes place in anoxic, or oxygen depleted zones, of freshwater bodies. In the case of Lake Constance, this is carried out by M. oxyfera-like bacteria.1 M. oxyfera-like bacteria are bacteria similar to Candidatus Methylomirabilis oxyfera, which is a species of bacteria that acts as a denitrifying methanotroph.3

The results from the study on Lake Constance found that nitrate was depleted in the water at the same depth as methane, which suggests that methane oxidation was coupled to denitrification. It could be inferred that it was M. oxyfera-like bacteria carrying out the methane oxidation because their abundance peaked at the same depth where the methane and nitrate profiles met.1 This n-damo process is significant because it aids in decreasing methane emissions from deep freshwater bodies and it aids in turning nitrates into nitrogen gas, reducing excess nitrates.

Sources:


 * 1) Deutzmann, Joerg S., Peter Stief, Josephin Brandes, and Bernhard Schink. "Anaerobic methane oxidation coupled to denitrification is the dominant methane sink in a deep lake." Proceedings of the National Academy of Sciences 111, no. 51 (2014): 18273-18278.
 * 2) Boucher, O., Friedlingstein, P., Collins, B., Shine, K. “The indirect global warming potential and global temperature change potential due to methane oxidation.” Environmental Research Letters. Vol 4. (2009).
 * Wu, M., van Teeseling M., Willems M., van Donselaar, E., Klingl, A., Rachel, R., Geerts, W., Jetten, M., Strous, M., van Niftrika, L. “Ultrastructure of the Denitrifying Methanotroph ‘Candidatus Methylomirabilis oxyfera,’ a Novel Polygon-Shaped Bacterium.” Journ. of Bacteriology. 284-291. (2011).

Denitrifying bacteria and wastewater treatment

Denitrifying bacteria are an essential component in treating wastewater. Wastewater often contains large amounts of nitrogen (in the form of ammonium or nitrate), which could be damaging to human health and ecological processes if left untreated. The process and methods vary, but it generally involves converting ammonium to nitrate, and finally to nitrogen gas. Since denitrifying bacteria are heterotrophic, an organic carbon source is supplied to the bacteria in an anoxic basin. With no available oxygen, denitrifying bacteria use the oxygen present in the nitrate to oxidize the carbon. This leads to the creation of nitrogen gas from nitrate, which then bubbles up out of the wastewater.1

Sources:

Ni, Bing-Jie, et al. “CHAPTER 16. Denitrification Processes for Wastewater Treatment.” Metalloenzymes in Denitrification Metallobiology, Nov. 2016, pp. 368–418., doi:10.1039/9781782623762-00368.