Elevated nitrate enriches microbial functional genes for potential bioremediation of complexly contaminated sediments

Abstract

Nitrate is an important nutrient and electron acceptor for microorganisms, having a key role in nitrogen (N) cycling and electron transfer in anoxic sediments. High-nitrate inputs into sediments could have a significant effect on N cycling and its associated microbial processes. However, few studies have been focused on the effect of nitrate addition on the functional diversity, composition, structure and dynamics of sediment microbial communities in contaminated aquatic ecosystems with persistent organic pollutants (POPs). Here we analyzed sediment microbial communities from a field-scale in situ bioremediation site, a creek in Pearl River Delta containing a variety of contaminants including polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs), before and after nitrate injection using a comprehensive functional gene array (GeoChip 4.0). Our results showed that the sediment microbial community functional composition and structure were markedly altered, and that functional genes involved in N-, carbon (C)-, sulfur (S)-and phosphorus (P)-cycling processes were highly enriched after nitrate injection, especially those microorganisms with diverse metabolic capabilities, leading to potential in situ bioremediation of the contaminated sediment, such as PBDE and PAH reduction/degradation. This study provides new insights into our understanding of sediment microbial community responses to nitrate addition, suggesting that indigenous microorganisms could be successfully stimulated for in situ bioremediation of POPs in contaminated sediments with nitrate addition.

Spatial and temporal dynamics of bacterioplankton community composition in a subtropical dammed karst river of southwestern China

“…Betaproteobacteria have a similar variation pattern, though they are often the most abundant bacteria inhabiting the upper waters of lakes (Newton et al., ). Previous studies demonstrated that Proteobacteria are involved in a variety of biogeochemical processes in aquatic ecosystems (Damashek & Francis, ; Xu et al., ; Zhang et al., ). Thus, they are more active due to a greater availability of POC and DOC at that depth, as seen in Figures d and a, which demonstrates that depth has a significant effect on their abundance in freshwater (Gattuso, Peduzzi, Pizay, & Tonolla, ).…”

Effectiveness and Mode of Action of Calcium Nitrate and Phoslock® in Phosphorus Control in Contaminated Sediment, a Microcosm Study

“…The most drastic change in nitrate treatment occurred in the top layer, in which NH 4 Cl-P increased from 4.08 mg P/ kg on day 1 to 39.9 mg P/kg on day 66. Increase of NH 4 Cl-P in nitrate treatment was likely attributed to the increase of P releasing from decaying cells of bacterial biomass in deposited phytodetrital aggregates as nitrate addition might increase the microbial activity in the sediment (Xu et al 2014).…”

“…Research had shown that nitrate addition could not only eliminate black-odorous and suppress internal phosphorus loading in the contaminated sediment but also successfully stimulate indigenous microorganisms for in situ bioremediation (Hemond and Lin 2010;Xu et al 2014;Yamada et al 2012). Phoslock®, a new lanthanum-modified bentonite, was developed in the 1990s by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) of Australia (Robb et al 2003), and had succeeded in reducing phosphorus in both laboratory and field trials (Meis et al 2012;Meis et al 2013;Lürling and van Oosterhout 2013).…”

Short-term enhancement effect of nitrogen addition on microbial degradation and plant uptake of polybrominated diphenyl ethers (PBDEs) in contaminated mangrove soil

“…Microbial degradation was one of the most important means to remove PBDEs from contaminated soil [9,26]. In the present study, the PBDE dissipation in the soil planted with A. corniculatum was significantly higher than that in the unplanted soil, and more PBDE dissipation occurred in rhizosphere (R) than non-rhizosphere (non-R) soil (Fig.…”