scholarly journals Water-driven microbial nitrogen transformations in biological soil crusts causing atmospheric nitrous acid and nitric oxide emissions

2021 ◽  
Author(s):  
S. Maier ◽  
A. M. Kratz ◽  
J. Weber ◽  
M. Prass ◽  
F. Liu ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitrous Acid ◽  
Biological Soil Crusts ◽  
N Cycling ◽  
Microbial Consortia ◽  
Nitrogen Transformations ◽  
Soil Crusts ◽  
Microbial Nitrogen ◽  
Genes Encoding ◽  
Denitrification Genes

AbstractBiological soil crusts (biocrusts) release the reactive nitrogen gases (Nr) nitrous acid (HONO) and nitric oxide (NO) into the atmosphere, but the underlying microbial process controls have not yet been resolved. In this study, we analyzed the activity of microbial consortia relevant in Nr emissions during desiccation using transcriptome and proteome profiling and fluorescence in situ hybridization. We observed that < 30 min after wetting, genes encoding for all relevant nitrogen (N) cycling processes were expressed. The most abundant transcriptionally active N-transforming microorganisms in the investigated biocrusts were affiliated with Rhodobacteraceae, Enterobacteriaceae, and Pseudomonadaceae within the Alpha- and Gammaproteobacteria. Upon desiccation, the nitrite (NO2−) content of the biocrusts increased significantly, which was not the case when microbial activity was inhibited. Our results confirm that NO2− is the key precursor for biocrust emissions of HONO and NO. This NO2− accumulation likely involves two processes related to the transition from oxygen-limited to oxic conditions in the course of desiccation: (i) a differential regulation of the expression of denitrification genes; and (ii) a physiological response of ammonia-oxidizing organisms to changing oxygen conditions. Thus, our findings suggest that the activity of N-cycling microorganisms determines the process rates and overall quantity of Nr emissions.

scholarly journals Emission of nitrous acid from soil and biological soil crusts represents an important source of HONO in the remote atmosphere in Cyprus

2018 ◽  
Vol 18 (2) ◽  
pp. 799-813 ◽  
Author(s):  
Hannah Meusel ◽  
Alexandra Tamm ◽  
Uwe Kuhn ◽  
Dianming Wu ◽  
Anna Lena Leifke ◽  
...  
Keyword(s):  
Nitrous Acid ◽  
Biological Soil Crust ◽  
Ground Surface ◽  
Field Studies ◽  
Bare Soil ◽  
Biological Soil Crusts ◽  
Soil Crusts ◽  
Wide Range ◽  
Mediterranean Island ◽  
Water Holding

Abstract. Soil and biological soil crusts can emit nitrous acid (HONO) and nitric oxide (NO). The terrestrial ground surface in arid and semiarid regions is anticipated to play an important role in the local atmospheric HONO budget, deemed to represent one of the unaccounted-for HONO sources frequently observed in field studies. In this study HONO and NO emissions from a representative variety of soil and biological soil crust samples from the Mediterranean island Cyprus were investigated under controlled laboratory conditions. A wide range of fluxes was observed, ranging from 0.6 to 264 ng m−2 s−1 HONO-N at optimal soil water content (20–30 % of water holding capacity, WHC). Maximum NO-N fluxes at this WHC were lower (0.8–121 ng m−2 s−1). The highest emissions of both reactive nitrogen species were found from bare soil, followed by light and dark cyanobacteria-dominated biological soil crusts (biocrusts), correlating well with the sample nutrient levels (nitrite and nitrate). Extrapolations of lab-based HONO emission studies agree well with the unaccounted-for HONO source derived previously for the extensive CYPHEX field campaign, i.e., emissions from soil and biocrusts may essentially close the Cyprus HONO budget.

scholarly journals Emission of nitrous acid from soil and biological soil crusts represents a dominant source of HONO in the remote atmosphere in Cyprus

2017 ◽  
Author(s):  
Hannah Meusel ◽  
Alexandra Tamm ◽  
Uwe Kuhn ◽  
Dianming Wu ◽  
Anna Lena Leifke ◽  
...  
Keyword(s):  
Nitrous Acid ◽  
Biological Soil Crust ◽  
Ground Surface ◽  
Field Studies ◽  
Bare Soil ◽  
Biological Soil Crusts ◽  
Soil Crusts ◽  
Wide Range ◽  
Mediterranean Island ◽  
Water Holding

Abstract. Soil and biological soil crusts can emit nitrous acid (HONO) and nitric oxide (NO). The terrestrial ground surface in arid and semi-arid regions is anticipated to play an important role in the local atmospheric HONO budget, deemed to represent one of the unaccounted HONO sources frequently observed in field studies. In this study HONO and NO emissions from a representative variety of soil and biological soil crust samples from the Mediterranean island Cyprus were investigated under controlled laboratory conditions. A wide range of fluxes was observed, ranging from 0.6 to 264 ng m−2 s−1 HONO-N at optimal soil water content (20–30 % of water holding capacity, WHC). Maximum NO-N at this WHC fluxes were lower (0.8–121 ng m−2 s−1). Highest emissions of both reactive nitrogen species were found from bare soil, followed by light and dark cyanobacteria-dominated biological soil crusts (biocrusts), correlating well with the sample nutrient levels (nitrite and nitrate). Extrapolations of lab-based HONO emission studies agree well with the unaccounted HONO source derived previously for the extensive CYPHEX field campaign, i.e., emissions from soil and biocrusts may essentially close the Cyprus HONO budget.

scholarly journals Phylogenomics reveals dynamic evolution of fungal nitric oxide reductases and their relationship to secondary metabolism

2018 ◽  
Author(s):  
Steven A. Higgins ◽  
Christopher W. Schadt ◽  
Patrick B. Matheny ◽  
Frank E. Löffler
Keyword(s):  
Nitric Oxide ◽  
Secondary Metabolism ◽  
Genomic Analysis ◽  
Primary Role ◽  
Ancestral State ◽  
The Novel ◽  
Gene Duplications ◽  
Genes Encoding ◽  
Denitrification Genes ◽  
Genomic Regions

AbstractFungi expressing P450nor, an unconventional nitric oxide (NO) reducing cytochrome P450, are thought to be significant contributors to soil nitrous oxide (N2O) emissions. However, fungal contributions to N2O emissions remain uncertain due to inconsistencies in measurements of N2O formation by fungi. Much of the N2O emitted from antibiotic-amended soil microcosms is attributed to fungal activity, yet fungal isolates examined in pure culture are poor N2O producers. To assist in reconciling these conflicting observations and produce a benchmark genomic analysis of fungal denitrifiers, genes underlying fungal denitrification were examined in >700 fungal genomes. Of 167p450nor–containing genomes identified, 0, 30, and 48 also harbored the denitrification genesnarG,napAornirK, respectively. Compared tonapAandnirK,p450norwas twice as abundant and exhibited two to five-fold more gene duplications, losses, and transfers, indicating a disconnect betweenp450norpresence and denitrification potential. Furthermore, co-occurrence ofp450norwith genes encoding NO-detoxifying flavohemoglobins (Spearman r = 0.87,p= 1.6e−10) confounds hypotheses regarding P450nor’s primary role in NO detoxification. Instead, ancestral state reconstruction united P450nor with actinobacterial cytochrome P450s (CYP105) involved in secondary metabolism (SM) and 19 (11 %)p450nor-containing genomic regions were predicted to be SM clusters. Another 40 (24 %) genomes harbored genes nearbyp450norpredicted to encode hallmark SM functions, providing additional contextual evidence linkingp450norto SM. These findings underscore the potential physiological implications of widespreadp450norgene transfer, support the novel affiliation ofp450norwith fungal SM, and challenge the hypothesis ofp450nor’s primary role in denitrification.

scholarly journals Expression of Nitrite and Nitric Oxide Reductases in Free-Living and Plant-Associated Agrobacterium tumefaciens C58 Cells

2005 ◽  
Vol 71 (8) ◽  
pp. 4427-4436 ◽  
Author(s):  
Seung-Hun Baek ◽  
James P. Shapleigh
Keyword(s):  
Nitric Oxide ◽  
Agrobacterium Tumefaciens ◽  
Nitrogen Atmosphere ◽  
Low Oxygen ◽  
Free Living ◽  
Nitric Oxide Synthase Inhibitor ◽  
Genes Encoding ◽  
Agrobacterium Tumefaciens C58 ◽  
Synthase Inhibitor ◽  
Denitrification Genes

ABSTRACT A number of the bacteria that form associations with plants are denitrifiers. To learn more about how the association with plants affects expression of denitrification genes, the regulation of nitrite and nitric oxide reductases was investigated in Agrobacterium tumefaciens. Analysis of free-living cells revealed that expression of the genes encoding nitrite and nitric oxide reductases, nirK and nor, respectively, requires low-oxygen conditions, nitric oxide, and the transcriptional regulator NnrR. Expression of nor was monitored in plant-associated bacteria using nor-gfp fusion expression. In root association experiments, only a small percentage of the attached cells were fluorescent, even when they were incubated under a nitrogen atmosphere. Inactivation of nirK had no significant effect on the ability of A. tumefaciens to bind to plant roots regardless of the oxygen tension, but it did decrease the occurrence of root-associated fluorescent cells. When wild-type cells containing the gfp fusion were infiltrated into leaves, most cells eventually became fluorescent. The same result was obtained when a nirK mutant was used, suggesting that nitric oxide activated nor expression in the endophytic bacteria. Addition of a nitric oxide synthase inhibitor to block nitric oxide generation by the plant prevented gfp expression in infiltrated nitrite reductase mutants, demonstrating that plant-derived nitric oxide can activate nor expression in infiltrated cells.

Experimental evidence for plasmid-bornenor-nirgenes inSinorhizobium melilotiJJ1c10

2004 ◽  
Vol 50 (9) ◽  
pp. 657-667 ◽  
Author(s):  
Yiu-Kwok Chan ◽  
Wayne A McCormick
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Sinorhizobium Meliloti ◽  
Nitrite Reduction ◽  
Nucleotide Sequence Analysis ◽  
Gene Products ◽  
Oxide Reduction ◽  
Accessory Gene ◽  
Genes Encoding ◽  
Denitrification Genes

In denitrification, nir and nor genes are respectively required for the sequential dissimilatory reduction of nitrite and nitric oxide to form nitrous oxide. Their location on the pSymA megaplasmid of Sinorhizobium meliloti was confirmed by Southern hybridization of its clones with specific structural gene probes for nirK and norCB. A 20-kb region of pSymA containing the nor-nir genes was delineated by nucleotide sequence analysis. These genes were linked to the nap genes encoding periplasmic proteins involved in nitrate reduction. The nor-nir-nap segment is situated within 30 kb downstream from the nos genes encoding nitrous oxide reduction, with a fix cluster intervening between nir and nos. Most of these predicted nor-nir and accessory gene products are highly homologous with those of related proteobacterial denitrifiers. Functional tests of Tn5 mutants confirmed the requirement of the nirV product and 1 unidentified protein for nitrite reduction as well as the norB-D products and another unidentified protein for nitric oxide reduction. Overall comparative analysis of the derived amino acid sequences of the S. meliloti gene products suggested a close relationship between this symbiotic N2fixer and the free-living non-N2-fixing denitrifier Pseudomonas G-179, despite differences in their genetic organization. This relationship may be due to lateral gene transfer of denitrification genes from a common donor followed by rearrangement and recombination of these genes.Key words: denitrification genes, nitric oxide reductase, nitrite reductase, Rhizobiaceae, Sinorhizobium meliloti.

scholarly journals Succession of N cycling processes in biological soil crusts on a Central European inland dune

2012 ◽  
Vol 83 (1) ◽  
pp. 149-160 ◽  
Author(s):  
Robert Brankatschk ◽  
Thomas Fischer ◽  
Maik Veste ◽  
Josef Zeyer
Keyword(s):  
Biological Soil Crusts ◽  
N Cycling ◽  
Central European ◽  
Soil Crusts

Discussion on wind factor influencing the distribution of biological soil crusts on surface of sand dunes

2013 ◽  
Vol 5 (6) ◽  
pp. 739
Author(s):  
Wu YongSheng ◽  
Erdun Hasi ◽  
Yin RuiPing ◽  
Zhang Xin ◽  
Ren Jie ◽  
...  
Keyword(s):  
Sand Dunes ◽  
Biological Soil Crusts ◽  
Soil Crusts

scholarly journals Exposure to low doses of pesticides induces an immune response and the production of nitric oxide in honeybees

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Merle T. Bartling ◽  
Susanne Thümecke ◽  
José Herrera Russert ◽  
Andreas Vilcinskas ◽  
Kwang-Zin Lee
Keyword(s):  
Nitric Oxide ◽  
Immune Responses ◽  
Bacterial Pathogen ◽  
Wild Plants ◽  
P450 Monooxygenase ◽  
Abiotic Stressors ◽  
Genes Encoding ◽  
Pesticides Exposure ◽  
Colony Survival ◽  
Oxide Synthase

AbstractHoneybees are essential pollinators of many agricultural crops and wild plants. However, the number of managed bee colonies has declined in some regions of the world over the last few decades, probably caused by a combination of factors including parasites, pathogens and pesticides. Exposure to these diverse biotic and abiotic stressors is likely to trigger immune responses and stress pathways that affect the health of individual honeybees and hence their contribution to colony survival. We therefore investigated the effects of an orally administered bacterial pathogen (Pseudomonas entomophila) and low-dose xenobiotic pesticides on honeybee survival and intestinal immune responses. We observed stressor-dependent effects on the mean lifespan, along with the induction of genes encoding the antimicrobial peptide abaecin and the detoxification factor cytochrome P450 monooxygenase CYP9E2. The pesticides also triggered the immediate induction of a nitric oxide synthase gene followed by the delayed upregulation of catalase, which was not observed in response to the pathogen. Honeybees therefore appear to produce nitric oxide as a specific defense response when exposed to xenobiotic stimuli. The immunity-related and stress-response genes we tested may provide useful stressor-dependent markers for ecotoxicological assessment in honeybee colonies.

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