Nitrification in terrestrial hot springs of Iceland and Kamchatka

Abstract

Archaea have been detected recently as a major and often dominant component of the microbial communities performing ammonia oxidation in terrestrial and marine environments. In a molecular survey of archaeal ammonia monooxygenase (AMO) genes in terrestrial hot springs of Iceland and Kamchatka, the amoA gene encoding the alpha-subunit of AMO was detected in a total of 14 hot springs out of the 22 investigated. Most of these amoA-positive hot springs had temperatures between 82 and 97 degrees C and pH range between 2.5 and 7. In phylogenetic analyses, these amoA genes formed three independent lineages within the known sequence clusters of marine or soil origin. Furthermore, in situ gross nitrification rates in Icelandic hot springs were estimated by the pool dilution technique directly on site. At temperatures above 80 degrees C, between 56 and 159 mumol NO(3)(-) L(-1) mud per day was produced. Furthermore, addition of ammonium to the hot spring samples before incubation yielded a more than twofold higher potential nitrification rate, indicating that the process was limited by ammonia supply. Our data provide evidence for an active role of archaea in nitrification of hot springs in a wide range of pH values and at a high temperature.

Crenarchaeol dominates the membrane lipids of Candidatus Nitrososphaera gargensis, a thermophilic Group I.1b Archaeon

“…Our results signify that all cultivated representatives of Group I Crenarchaeota to date synthesize crenarchaeol, thus providing support for the suggested specificity of crenarchaeol to Archaea involved in ammonia oxidation (de la Torre et al, 2008). Crenarchaeol has also been detected at sites of archaeal ammonia oxidation in the marine water column of the coastal North Sea (Wuchter et al, 2006), the Black Sea , Icelandic hot springs (Reigstad et al, 2008), Nevada and California hot springs (Pearson et al, 2004;Zhang et al, 2006;Pitcher et al, 2009) and agricultural soils (Leininger et al, 2006). Although Wuchter et al (2006) and Leininger et al (2006) found a strong correlation between crenarchaeol abundance and amoA copy numbers, but because of a lack of cultured representatives from Group I Crenarchaeota falling outside the recognized AOA, it yet cannot be unambiguously concluded that crenarchaeol synthesis is actually restricted to AOA.…”

Abundances and potential activities of nitrogen cycling microbial communities along a chronosequence of a glacier forefield

“…De Boer and Kowalchuk (2001) found that Nitrosospira species, which are the most common AOB in soil (Kowalchuk et al, 2000), were not able to oxidize ammonium at pH values below 5.5. In contrast, several studies indicate that AOA are able to oxidize ammonium in a broad pH range (Leininger et al, 2006;Nicol et al, 2008;Reigstad et al, 2008) and appear to be better adapted to ammonium-poor environments (Di et al, 2009(Di et al, , 2010 and soils with low pH (Nicol et al, 2008).…”

A robust nitrifying community in a bioreactor at 50 °C opens up the path for thermophilic nitrogen removal

“…Thermophilic ammonia oxidation is fueling hydrothermal and geothermal life. Many archaeal ammonia monooxygenase subunit A (amoA) genes have been detected in high-temperature habitats such as deep-sea hydrothermal vents (Wang et al, 2009;Baker et al, 2012), subsurface thermal springs (Spear et al, 2007;Weidler et al, 2008) and terrestrial hot springs (Reigstad et al, 2008;Dodsworth et al, 2011). In addition to these oligotrophic ecosystems, the amoA gene was also found in nutrient-rich high-temperature engineered environments such as petroleum reservoirs and composting facilities (Zeng et al, 2011).…”