Evaluating wastewater stabilizing constructed wetland, through diversity and abundance of the nitrite reductase gene nirS, with regard to nitrogen control

Nitrate removal, communities of denitrifiers and adverse effects in different carbon substrates for use in denitrification beds

“…6A), but the ${\text{NO}}_3^{-}-\text{N}$ removal rate increased 1.2 times. This temperature dependence of denitrification genes corresponds with seasonal measurements of nitrite reductase gene copies in wetlands (Chon et al, 2010). The copies of 16S rRNA genes also increased with temperature, with the exception of the sawdust barrel (Table 2), so the greater copy number of denitrification genes in the substrate at higher temperature was also partially due to an increase in bacterial biomass.…”

“…Additionally, nitrite reductase genes ( nirS and nirK ), which are responsible for the second step of denitrification, were on average more abundant in this study (Table 2) than in constructed wetlands (Chon et al, 2010), or rice fields (Yoshida et al, 2009). Furthermore, the significant linear relationship of the increase of ${\text{NO}}_3^{-}$ removal, and the increase of measured DR + C/N, indicated that microbial denitrification was responsible for the ${\text{NO}}_3^{-}-\text{N}$ removal, regardless of the carbon substrate in the experimental barrels and showed that the acetylene inhibition method was a good measure for comparative ${\text{NO}}_3^{-}$ removal estimations between C substrates (Fig.…”

“…6A), and these values were on average greater than those measured in constructed wetlands or rice fields (Chon et al, 2010; Yoshida et al, 2009). However, the abundance of denitrification genes in pine and eucalyptus woodchips were slightly lower, but in the same range as the wetland and rice field studies (Chon et al, 2010; Yoshida et al, 2009). But woodchips, especially those from cold incubations, showed the greatest abundance of nitrite reductase genes as a proportion of total bacterial DNA (16S rRNA), coupled with low 16S rRNA gene copies (Table 2, Fig.…”

“…Interestingly many denitrifying organisms have been shown to reduce ${\text{NO}}_3^{-}$ only to nitrous oxide (Cheneby et al, 1998, 2004) and some, such as Agrobacterium tumerfaciens C58 do not possess nitrous oxide reductase ( nosZ ) (Wood et al, 2001). Many studies have shown that differences in the diversity and abundance of denitrifying bacterial genes were correlated to a variety of physical and chemical conditions; organic carbon in glacier foreland (Kandeler et al, 2006), temperature in constructed wetlands (Chon et al, 2010), water logging in rice paddy soils (Yoshida et al, 2009), organic or conventional fertilizer in agricultural soils (Dambreville et al, 2006; Enwall et al, 2005), native and cultivated soils (Stres et al, 2004), soil pH in grassland soils (Cuhel et al, 2010), nitrous-oxide emissions (Philippot et al, 2009) and ${\text{NO}}_3^{-}$ concentration in woodlands with different vegetation (Lindsay et al, 2010). However, the diversity and abundance of denitrifying bacteria under consistent environmental conditions (e.g., same temperature, ${\text{NO}}_3^{-}$ concentration, DO concentration, flow rate), but with different carbon substrates are poorly known.…”

Treatment of petrochemical wastewater by microaerobic hydrolysis and anoxic/oxic processes and analysis of bacterial diversity

“…Some species of the genus Defluviicoccus were related to glycogen accumulating organisms that are able to anaerobic uptake of acetate and propionate as carbon source (Dai et al, 2007). The bacteria of genus Xanthomonadales belonged to the heterotrophic denitrifiers, which were detected in a constructed wetland and played an important role in denitrification (Chon et al, 2010).…”