Temperature response of denitrification and anaerobic ammonium oxidation rates and microbial community structure in Arctic fjord sediments

Abstract

The temperature dependency of denitrification and anaerobic ammonium oxidation (anammox) rates from Arctic fjord sediments was investigated in a temperature gradient block incubator for temperatures ranging from -1 to 40°C. Community structure in intact sediments and slurry incubations was determined using Illumina SSU rRNA gene sequencing. The optimal temperature (Topt ) for denitrification was 25-27°C, whereas anammox rates were optimal at 12-17°C. Both denitrification and anammox exhibited temperature responses consistent with a psychrophilic community, but anammox bacteria may be more specialized for psychrophilic activity. Long-term (1-2 months) warming experiments indicated that temperature increases of 5-10°C above in situ had little effect on the microbial community structure or the temperature response of denitrification and anammox. Increases of 25°C shifted denitrification temperature responses to mesophilic with concurrent community shifts, and anammox activity was eliminated above 25°C. Additions of low molecular weight organic substrates (acetate and lactate) caused increases in denitrification rates, corroborating the hypothesis that the supply of organic substrates is a more dominant control of respiration rates than low temperature. These results suggest that climate-related changes in sinking particulate flux will likely alter rates of N removal more rapidly than warming.

Biotic and abiotic controls on co-occurring nitrogen cycling processes in shallow Arctic shelf sediments

“…Temperature block experiments have demonstrated that denitrification rates of Arctic-adapted microbes are highest at temperatures between 20 and 25 °C (ref. 17), but many other factors in situ can regulate the process. Thus, in the literature surveyed there is no clear temperature regulation of denitrification, anammox, or DNRA.…”

“…NO 3 − concentrations often correlate positively with ra , although multiple environmental factors in concert, including sediment reactivity, can explain ra better than any one sole factor15. Temperature may also have a regulatory role for the two processes since the optimum temperature for polar-adapted denitrifying bacteria is 20–25 °C, while the optimum temperature for polar-adapted anammox bacteria is lower, at 9–12 °C (refs 16, 17). While these data suggest that anammox may have a competitive advantage in perennially cold Arctic sediments, results from temperature block experiments showed ra at 2.5 °C was only ∼22% (ref.…”

Occurrence and importance of anaerobic ammonium-oxidising bacteria in vegetable soils

“…The microbial process is regulated by various environmental factors, and many studies have reported the controlling factors of anammox bacterial abundance and activity, primarily including the temperature (Schubert et al 2006;Hou et al 2013;Zhao et al 2013;Canion et al 2014), water column NO 3 − /NO 2 − availability (Meyer et al 2005;Rich et al 2008;Nicholls and Trimmer 2009;Hou et al 2013), sediment organic carbon concentration (Dalsgaard and Thamdrup 2002;Trimmer et al 2003;Hu et al 2012a) and salinity (Dale et al 2009;Hou et al 2013;Sonthiphand et al 2014). In the current study, Pearson moment correlation analyses showed that both the activity and abundance of anammox bacteria significantly correlated with the soil ammonium concentration in the examined soil cores (Table 3).…”

Effect of temperature downshifts on biological nitrogen removal and community structure of a lab-scale aerobic denitrification process

“…S3). Over the past decade, multiple studies have investigated the effect of transiently or permanently low temperatures on the nitrification and denitrification of microbial community shifts in natural soil and aquatic environments [43,44]. Low temperatures reduced bacterial richness and enriched psychrotolerant species in engineering samples [45,46].…”