1.Ammonia-limited conditions cause of Thaumarchaeal dominance in volcanic grassland soil.
Daebeler A1, Bodelier PL2, Hefting MM3, Laanbroek HJ4. FEMS Microbiol Ecol. 2015 Mar;91(3). pii: fiv014. doi: 10.1093/femsec/fiv014. Epub 2015 Feb 5.
The first step of nitrification is carried out by ammonia-oxidizing bacteria (AOB) and archaea (AOA). It is largely unknown, by which mechanisms these microbes are capable of coexistence and how their respective contribution to ammonia oxidation may differ with varying soil characteristics. To determine how different levels of ammonium availability influence the extent of archaeal and bacterial contributions to ammonia oxidation, microcosm incubations with controlled ammonium levels were conducted. Net nitrification was monitored and ammonia-oxidizer communities were quantified. Additionally, the nitrification inhibitor allylthiourea (ATU) was applied to discriminate between archaeal and bacterial contributions to soil ammonia oxidation. Thaumarchaeota, which were the only ammonia oxidizers detectable at the start of the incubation, grew in all microcosms, but AOB later became detectable in ammonium amended microcosms. Low and high additions of ammonium increasingly stimulated AOB growth, while AOA were only stimulated by the low addition.
2.Inhibition of nitrification in municipal wastewater-treating photobioreactors: Effect on algal growth and nutrient uptake.
Krustok I1, Odlare M2, Truu J3, Nehrenheim E2. Bioresour Technol. 2016 Feb;202:238-43. doi: 10.1016/j.biortech.2015.12.020. Epub 2015 Dec 17.
The effect of inhibiting nitrification on algal growth and nutrient uptake was studied in photobioreactors treating municipal wastewater. As previous studies have indicated that algae prefer certain nitrogen species to others, and because nitrifying bacteria are inhibited by microalgae, it is important to shed more light on these interactions. In this study allylthiourea (ATU) was used to inhibit nitrification in wastewater-treating photobioreactors. The nitrification-inhibited reactors were compared to control reactors with no ATU added. Microalgae had higher growth in the inhibited reactors, resulting in a higher chlorophyll a concentration. The species mix also differed, with Chlorella and Scenedesmus being the dominant genera in the control reactors and Cryptomonas and Chlorella dominating in the inhibited reactors. The nitrogen speciation in the reactors after 8days incubation was also different in the two setups, with N existing mostly as NH4-N in the inhibited reactors and as NO3-N in the control reactors.
3.Molecularly imprinted polymer dedicated to the extraction of glyphosate in natural waters.
Puzio K1, Claude B2, Amalric L3, Berho C3, Grellet E3, Bayoudh S4, Nehmé R1, Morin P1. J Chromatogr A. 2014 Sep 26;1361:1-8. doi: 10.1016/j.chroma.2014.07.043. Epub 2014 Jul 22.
Three molecularly imprinted polymers (MIPs) have been synthesized in order to bind efficiently glyphosate (GLY) in natural waters (mineral and underground). Since the target analyte is polar and hydrophilic, electrostatic interactions and hydrogen bonds have been favored with two templates (phenylphosphonic acid and diethyl(α-aminobenzyl)-phosphonic acid) and two functional monomers (1-allyl-2-thiourea and methacrylic acid). MIPs have been assessed by comparison of the recoveries obtained with MIP and NIP (non imprinted polymer) by solid-phase extraction (SPE). The selectivity of MIP versus NIP was satisfactory for the three imprinted polymers with a very straightforward protocol: conditioning of 250 mg of MIP or NIP packed in 3-mL polypropylene cartridges with 3 mL Milli-Q water, loading of Milli-Q water (15 mL) spiked with 5 mg L(-1) of GLY and its metabolite, aminomethylphosphonic acid (AMPA) and elution by 3 mL NH4OH (10mM) or 3 mL HCl (100mM).
4.Enhanced transformation of tetrabromobisphenol a by nitrifiers in nitrifying activated sludge.
Li F1, Jiang B2, Nastold P3, Kolvenbach BA3, Chen J4, Wang L1, Guo H1, Corvini PF1,3, Ji R1. Environ Sci Technol. 2015 Apr 7;49(7):4283-92. doi: 10.1021/es5059007. Epub 2015 Mar 23.
The fate of the most commonly used brominated flame retardant, tetrabromobisphenol A (TBBPA), in wastewater treatment plants is obscure. Using a (14)C-tracer, we studied TBBPA transformation in nitrifying activated sludge (NAS). During the 31-day incubation, TBBPA transformation (half-life 10.3 days) was accompanied by mineralization (17% of initial TBBPA). Twelve metabolites, including those with single benzene ring, O-methyl TBBPA ether, and nitro compounds, were identified. When allylthiourea was added to the sludge to completely inhibit nitrification, TBBPA transformation was significantly reduced (half-life 28.9 days), formation of the polar and single-ring metabolites stopped, but O-methylation was not significantly affected. Abiotic experiments confirmed the generation of mono- and dinitro-brominated forms of bisphenol A in NAS by the abiotic nitration of TBBPA by nitrite, a product of ammonia-oxidizing microorganisms (AOMs). Three biotic (type II ipso-substitution, oxidative skeletal cleavage, and O-methylation) and one abiotic (nitro-debromination) pathways were proposed for TBBPA transformation in NAS.