Microbial potential for denitrification in the hyperarid Atacama Desert soils. (June 2021)

• Record Type: Journal Article
• Authors: Wu, Di; Senbayram, Mehmet; Moradi, Ghazal; Mörchen, Ramona; Knief, Claudia; Klumpp, Erwin; Jones, Davey L.; Well, Reinhard; Chen, Ruirui; Bol, Roland
• Is Part Of: Soil biology and biochemistry. Volume 157(2021)
• Publication Date: 2021-06
• Subjects: Denitification -- Greenhouse gases -- Nitrogen cycling -- Moisture status -- Xerophile; Soil biochemistry -- Periodicals; Soil biology -- Periodicals; Sols -- Biochimie -- Périodiques; Sols -- Biologie -- Périodiques; Sols -- Microbiologie -- Périodiques; Bodembiologie; Biochemie; 631.46
• DOI: 10.1016/j.soilbio.2021.108248
• Languages: English
• ISSNs: 0038-0717

Abstract

Abstract: The hyperarid soils of the Atacama Desert, Chile, contain the largest known nitrate deposits in the world. They also represent one of the most hostile environments for microbial life anywhere in the terrestrial biosphere. Despite known for its extreme dryness, several heavy rainfall events causing localised flash flooding have struck Atacama Desert core regions during the last five years. It remains unclear, however, whether these soils can support microbial denitrification. To answer this, we sampled soils along a hyperaridity gradient in the Atacama Desert and conducted incubation experiments using a robotized continuous flow system under a He/O2 atmosphere. The impacts of four successive extreme weather events on soil-borne N2 O and N2 emissions were investigated, i) water addition, ii) NO3 − addition, iii) labile carbon (C) addition, and iv) oxygen depletion. The 15 N–N2 O site-preference (SP) approach was further used to examine the source of N2 O produced. Extremely low N2 O fluxes were detected shortly after water and NO3 − addition, whereas pronounced N2 O and N2 emissions were recorded after labile-C (glucose) amendment in all soils. Under anoxia, N2 emissions increased drastically while N2 O emissions decreased concomitantly, indicating the potential for complete denitrification at all sites. Although increasing aridity significantly reduced soil bacterial richness, microbial potential for denitrification and associated gene abundance (i.e., napA, narG, nirS, nirK, cnorB, qnorB and nosZ ) was not affected. The N2 O 15 N site preference values based on two end-member model suggested that fungal and bacterial denitrification co-contributed to N2 O production in less arid sites, whereas bacterial denitrification dominated with increasing aridity. We conclude that soil denitrification functionality is preserved even with lowered microbial richness in the extreme hyperarid Atacama Desert. Future changes in land-use or extreme climate events therefore have a potential to destabilize the immense reserves of nitrate and induce significant N2 O losses in the region. Highlights: Denitrification was shown to occur in the hyperarid Atacama Desert. Denitrification potential and associated gene abundance was not affected by aridity. Increasing aridity reduced soil bacterial richness. Fungal and bacterial denitrification co-contributed to N2 O production. Bacterial denitrification dominated N2 O production with increasing hyperaridity.