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University of Nevada, Las Vegas; Center for Academic Enrichment and Outreach


Temperature has strong impacts on ecosystem function and biogeochemical cycles, particularly within extreme environments such as geothermal springs above 60 °C. The primary focus of this study was to investigate the denitrification pathways of Thermus (Bacteria) isolates from geothermal springs from Tengchong, China. This study tested the hypothesis that incomplete denitrification is a common characteristic of the genus Thermus, regardless of geographic origin or species affiliation, which would implicate them in the efflux of nitrous oxide (a strong greenhouse gas) to the atmosphere. In this study, we cultivated 25 isolates, including six known Thermus species, and measured the stoichiometry of nitrogenous products of nitrate respiration using gas chromatography and colorimetric assays. We also designed custom primers for polymerase chain reaction (PCR) amplification of denitrification genes including narG, nirS, nirK, and norB to screen for the genetic capacity for each step in denitrification. Experimental results show that all Thermus strains tested display incomplete denitrification pathways terminating at nitrite (NO2 -) or nitrous oxide (N2O), and possibly nitric oxide (NO).


Biogeochemical cycles; Denitrification; Gas chromatography; Greenhouse gases; Ecosystem management; Extreme environments; Nitrous oxide; Polymerase chain reaction; Stoichiometry; Temperature


Biology | Life Sciences



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