A novel perchlorate- and nitrate-reducing bacterium, Azospira sp. PMJ

Abstract

A novel perchlorate-reducing bacterium (PCRB), PMJ, was isolated from the mixed liquor suspended solids in the aerobic tank of a wastewater treatment plant. The 16S ribosomal RNA (rRNA), perchlorate reductase, and chlorite dismutase gene sequences revealed that PMJ belonged to the genus Azospira. PMJ was removed high-strength (700 mg/L) perchlorate and also removed low-strength (≤50 mg/L) perchlorate below the detection limit (2 μg/L) when acetate was used as a sole and carbon source. The maximum specific perchlorate utilization rate, q max, was 0.96 mg ClO4 (-)/mg dry cell weight day, and the half-saturation constant, K S , was lower than 0.002 mg ClO4 (-)/L. PMJ also utilized inorganic electron donors [(H2, S(0), and Fe(II)] with perchlorate as an electron acceptor. Perchlorate reduction by PMJ was completely inhibited by oxygen and chlorate but was not inhibited by nitrate. In the presence of similar concentrations (100∼140 mg/L) of nitrate and perchlorate, PMJ simultaneously removed both electron acceptors. Therefore, it was concluded that the strains PMJ might possess separate pathways for perchlorate and nitrate reduction. These results indicated that Azospira sp. PMJ could be efficiently used for treating perchlorate-contaminated groundwater and wastewater because many of these water bodies are known to contain both perchlorate and nitrate. In addition, low K S value and autotrophic perchlorate reduction of PMJ might be useful to design the biological treatment systems.

Survival strategy of comammox bacteria in a wastewater nutrient removal system with sludge fermentation liquid as additional carbon source

“…1). Denitrifying Azospira (6.51%), Haliangium (2.14%), Hyphomicrobium (0.90%), and Dechloromonas (0.23%) increased significantly, as they were able to grow on simple organic acids (Osaka et al 2006, Gliesche et al 2015, Nam et al 2016). The PAO Candidatus Accumulibacter (6.26%) were 2.3-9.5 times more abundant than those in phase I.…”

Natural attenuation of pools and plumes of carbon tetrachloride and chloroform in the transition zone to bottom aquitards and the microorganisms involved in their degradation

“…), where it accumulates and remains attached to the surface of mineral grains. This microorganism is an anaerobic, nitrate-dependent bacterium that rapidly uses the Fe(II) content of natural sediments as an electron donor under anoxic conditions and nitrate as the electron acceptor (Achenbach et al, 2001) to produce mixed-valence Fe(II)-Fe(III) byproduct precipitates, which are unstable iron minerals that correspond to green rusts (Chaudhuri et al, 2001;Lack et al, 2002;Weber et al, 2006;Nam et al;. Studies by different authors have confirmed the abiotic reductive dechlorination process of CT in the presence of green rusts (Liang and Butler, 2010;Yin et al, 2017), which are common natural electron donors in aquifers (Matocha, Dhakal and Pyzola, 2012) The high geological heterogeneity in the TZBA, with the presence of numerous interbedded layers of silty-clays, sands, and gravels with variable fine matrix content in this unit (see Section 4.1), accounts for the high textural heterogeneity observed, with abundant textural contrasts between fine and coarse materials.…”

Dissimilatory and Cytoplasmic Antimonate Reductions in a Hydrogen-Based Membrane Biofilm Reactor

“…Another exception was Dechloromonas, which decreased slightly in S2, but increased in S3. Dechloromonas, Sporomusa, unclassified_f_Rhodocyclaceae, Derxia, and Azospira are identified as hydrogen-oxidizing DSbRB that have an arrA gene; additional details about the DSbRB are presented in the Supporting Information. In general, the change in major abundance of autotrophic DSbRB was positive relative to the influent Sb­(V) concentration (ρ > 0.3, detailed in Table S5), indicating that DSbRB have a dissimilation Sb­(V) respiration capacity using Sb­(V) as an energy source.…”