Plant-Microbe Interactions Drive Denitrification Rates, Dissolved Nitrogen Removal, and the Abundance of Denitrification Genes in Stormwater Control Measures

Abstract

The microbial community and function along with nitrate/nitrite (NOx) removal rates, and nitrogen (N) partitioning into "uptake", "denitrification", and "remaining" via isotope tracers, were studied in soil bioretention mesocolumns (8 unique plant species). Total denitrification gene reads per million (rpm) were positively correlated with % denitrified ( r = 0.69) but negatively correlated with total NOx removal following simulated rain events ( r = -0.79). This is likely due to plant-microbe interactions. Plant species with greater root volume, plant and microbial assimilation %, and NOx removal % had lower denitrification genes and rates. This implies that although microorganisms have access to N, advantageous functions, like denitrification, may not increase. At the conclusion of the 1.5-year experiment, the microbial community was strongly influenced by plant species within the Top zone dominated by plant roots, and the presence or absence of a saturated zone influenced the microbial community within the Bottom zone. Leptospermum continentale was an outlier from the other plants and had much lower denitrification gene rpm (average 228) compared to the other species (range: 277 to 413). The antimicrobial properties and large root volume of Leptospermum continentale likely caused this denitrification gene depression.

Metagenomic analysis reveals distinct patterns of denitrification gene abundance across soil moisture, nitrate gradients

“…S4), indicating that there was not a notable selective loss of members of the community at the agricultural field site. Complex N-competition relationships with crop plants might account for lesser nar read abundance at the agricultural field site (Morse, 2018), but it is unclear why this would not likewise impact nap.…”

“…Sequence comparisons to identify reads derived from N-oxide genes were done using DIAMOND (Buchfink et al, 2015). Taxonomic assignment of metagenomic reads was performed using a clustering and alignment-based approach, which is described in the study by Morse et al, 2018. These data sets were manually curated to confirm protein assignments and are available at http://hdl.…”

“…A validation of the specificity of cNor or qNor read assignment also relied on a similar approach (see supporting information for more details). Taxonomic assignment of metagenomic reads was performed using a clustering and alignment-based approach, which is described in the study by Morse et al, 2018.…”

Performance Assessment of a Laboratory Scale Prototype Biofiltration System in Tropical Region

“…Further analysis through Kruskal-Wallis test indicated that there was no significant statistical difference between the inlet and outlet median TN concentrations for all groups as p > 0.05 (see Table 3). Therefore, TN concentration was independent from depth for Cyperus and Pedilanthus in the box biofilter, and this was likely because of little or no denitrification in the biofiltration system [46,47]. Further analyses were conducted to either prove or reject the hypothesis of correlation between TN removal and depth.…”

Real time control schemes for improving water quality from bioretention cells

“…Previous work researching bioretention systems have used local climate data to determine dosing volumes. Chandrasena et al (2017) report using a storm size of 5.75 mm per event while Glaister et al (2017) and Morse et al (2018) used a local yearly average of 540 mm. Each storm event was applied based on 20:1 sizing ratio for each column (TSM 2015).…”