Diagnóstico y tratamiento del lipedema en España. Resultados de encuesta online / Diagnosis and treatment of lipedema in Spain. Results of an online survey

Introducción: El lipedema es el depósito de tejido graso doloroso fundamentalmente en miembros inferiores. Afecta casi siempre a mujeres, y está infradiagnosticado e infratratado. El objetivo del estudio es describir las características del diagnóstico y los tipos de tratamientos realizados por los pacientes con lipedema en España. Material y métodos: Estudio descriptivo transversal mediante encuesta online anónima realizada entre noviembre-diciembre 2019. Se calculó el tamaño muestral mínimo para un nivel de confianza del 95% y margen de error del 5%. Se recogieron las variables sociodemográficas (edad, sexo y comunidad de residencia), aspectos diagnósticos y la mejoría percibida con diferentes opciones de tratamiento. Resultados: Se obtuvieron 463 respuestas válidas. La edad media de inicio de la sintomatología fue de 18,2 años (DE: 9,0). El 69% de los pacientes comenzaron con clínica entre los 10-19 años. Transcurrieron 19,9 años (DE: 10,1) desde el inicio de la clínica, y se necesitaron 4,9 visitas médicas (DE: 3,3) para obtener un diagnóstico. El diagnóstico se realizó con más frecuencia en la medicina privada por cirujanos. El 78,4% de los pacientes probaron, al menos, 3 tipos diferentes de tratamientos. La pérdida de peso fue el tratamiento más utilizado y las prendas de compresión la opción percibida como más efectiva. Un 34% de los pacientes tienen acceso a la prescripción de prendas de compresión. Conclusiones: Actualmente el lipedema carece de un tratamiento estandarizado, y las diferentes terapias realizadas no son percibidas como satisfactorias por los pacientes. Es necesario mejorar su conocimiento para obtener un diagnóstico temprano y proporcionar a los pacientes tratamientos adecuados.(AU)

Introduction: Lipedema is a chronic and progressive disease. Most studies agree that it is underdiagnosed and undertreated. The aim of this study was to identify the diagnostic characteristics and types of treatment for lipedema in the Spanish population. Material and methods: A cross-sectional descriptive study was carried out through an anonymous 10-item online survey in November- December 2019. The minimum sample size was calculated for a 95% confidence level and 5% margin of error. Information was collected on sociodemographic variables (age, sex, place of residence), diagnostic characteristics and perceived improvement with distinct treatment options. Results: A total of 463 valid responses were obtained. The mean age at first manifestation was 18.2 (SD: 9.0) years. Onset occurred between the ages of 10 and 19 years in 69% of the patients. It took an average of 19.9 (SD: 10.1) years to receive a diagnosis and 4.9 medical visits. Diagnosis was most frequently made in private clinics by surgeons. Most patients (78.4%) had tried at least three different types of treatment. Weight loss was the most frequent treatment (92%) and compression garments were perceived to be the most effective. Only 34% of respondents had access to financing for compression garments. Conclusions: Currently, there is no standard treatment for lipedema and patients perceive current treatments to be unsatisfactory. Better knowledge of this entity is needed to allow early diagnosis and provide adequate treatment.(AU)

TbasCO: trait-based comparative 'omics identifies ecosystem-level and niche-differentiating adaptations of an engineered microbiome.

A grand challenge in microbial ecology is disentangling the traits of individual populations within complex communities. Various cultivation-independent approaches have been used to infer traits based on the presence of marker genes. However, marker genes are not linked to traits with complete fidelity, nor do they capture important attributes, such as the timing of gene expression or coordination among traits. To address this, we present an approach for assessing the trait landscape of microbial communities by statistically defining a trait attribute as a shared transcriptional pattern across multiple organisms. Leveraging the KEGG pathway database as a trait library and the Enhanced Biological Phosphorus Removal (EBPR) model microbial ecosystem, we demonstrate that a majority (65%) of traits present in 10 or more genomes have niche-differentiating expression attributes. For example, while many genomes containing high-affinity phosphorus transporter pstABCS display a canonical attribute (e.g. up-regulation under phosphorus starvation), we identified another attribute shared by many genomes where transcription was highest under high phosphorus conditions. Taken together, we provide a novel framework for unravelling the functional dynamics of uncultivated microorganisms by assigning trait-attributes through genome-resolved time-series metatranscriptomics.

[Diagnosis and treatment of lipedema in Spain. Results of an online survey]. / Diagnóstico y tratamiento del lipedema en España. Resultados de encuesta online.

INTRODUCTION: Lipedema is a chronic and progressive disease. Most studies agree that it is underdiagnosed and undertreated. The aim of this study was to identify the diagnostic characteristics and types of treatment for lipedema in the Spanish population. MATERIAL AND METHODS: A cross-sectional descriptive study was carried out through an anonymous 10-item online survey in November- December 2019. The minimum sample size was calculated for a 95% confidence level and 5% margin of error. Information was collected on sociodemographic variables (age, sex, place of residence), diagnostic characteristics and perceived improvement with distinct treatment options. RESULTS: A total of 463 valid responses were obtained. The mean age at first manifestation was 18.2 (SD: 9.0) years. Onset occurred between the ages of 10 and 19 years in 69% of the patients. It took an average of 19.9 (SD: 10.1) years to receive a diagnosis and 4.9 medical visits. Diagnosis was most frequently made in private clinics by surgeons. Most patients (78.4%) had tried at least three different types of treatment. Weight loss was the most frequent treatment (92%) and compression garments were perceived to be the most effective. Only 34% of respondents had access to financing for compression garments. CONCLUSIONS: Currently, there is no standard treatment for lipedema and patients perceive current treatments to be unsatisfactory. Better knowledge of this entity is needed to allow early diagnosis and provide adequate treatment.

Revisión sistemática del tratamiento de la espasticidad en el adulto con daño cerebral adquirido / Systematic review of the treatment of spasticity in acquired adult brain damage

La espasticidad es un trastorno motor, caracterizado por un aumento del tono muscular, y que aparece como consecuencia de un trastorno del sistema nervioso central, dando lugar a déficit y discapacidad, con deterioro de la calidad de vida. En el daño cerebral adquirido del adulto, la espasticidad constituye un problema grave y frecuente, apareciendo en un 20-30% de pacientes con ictus y en un 13-20% de pacientes con traumatismo craneoencefálico moderado-grave. El objetivo principal de este trabajo es realizar una revisión sistemática de los tratamientos utilizados en la espasticidad del paciente adulto con daño cerebral adquirido secundario a ictus y traumatismo craneoencefálico. Como objetivo secundario se pretende averiguar las principales escalas de valoración utilizadas para la medida de la espasticidad en estos pacientes. Se ha realizado una búsqueda sistemática de ensayos controlados aleatorizados, publicados entre el 1 de enero de 2013 y 30 de junio de 2017 en inglés y castellano, en las bases de datos PubMed, Biblioteca Cochrane plus y Ovid. Se han seleccionado finalmente 17 estudios, con una calidad metodológica al menos aceptable, según la escala de Jadad. Los tratamientos más frecuentemente investigados son la toxina botulínica, especialmente el serotipo A, junto a medidas rehabilitadoras. Las escalas clínicas son las más frecuentemente utilizadas para la evaluación de la espasticidad

Spasticity is a motor disorder characterised by an increase in muscle tone that appears as a consequence of a central nervous system disorder, leading to deficit and disability and impairing quality of life. In acquired adult brain damage, spasticity is a severe and frequent problem, appearing in 20-30% of patients with stroke and in 13-20% of patients with moderate-severe traumatic brain injury. The main objective of this study was to perform a systematic review of the treatments used in spasticity in adult patients with acquired brain damage secondary to stroke and head trauma. A systematic search of randomised controlled trials, published between January 1, 2013 and June 30, 2017 in English and Spanish, was carried out in the PubMed, Cochrane plus Library and Ovid databases. We finally selected 17 studies, with methodological quality that was at least acceptable according to the Jadad scale. The most frequently investigated treatments are botulinum toxin, especially serotype A, together with rehabilitative measures. Clinical scales are the most frequently used to assess spasticity

[Systematic review of the treatment of spasticity in acquired adult brain damage]. / Revisión sistemática del tratamiento de la espasticidad en el adulto con daño cerebral adquirido.

Spasticity is a motor disorder characterised by an increase in muscle tone that appears as a consequence of a central nervous system disorder, leading to deficit and disability and impairing quality of life. In acquired adult brain damage, spasticity is a severe and frequent problem, appearing in 20-30% of patients with stroke and in 13-20% of patients with moderate-severe traumatic brain injury. The main objective of this study was to perform a systematic review of the treatments used in spasticity in adult patients with acquired brain damage secondary to stroke and head trauma. A systematic search of randomised controlled trials, published between January 1, 2013 and June 30, 2017 in English and Spanish, was carried out in the PubMed, Cochrane plus Library and Ovid databases. We finally selected 17 studies, with methodological quality that was at least acceptable according to the Jadad scale. The most frequently investigated treatments are botulinum toxin, especially serotype A, together with rehabilitative measures. Clinical scales are the most frequently used to assess spasticity.

Evaluation of acid-phase digestion as a pretreatment to enhance co-digestion of source separated organics and municipal sewage sludges.

This work assessed if acid-phase digestion could improve volatile solids (VS) destruction and methane yield when co-digesting municipal sewage sludges (primary and waste activated sludge) and source separated organics (SSO). The SSO was made up of food waste and the organic fraction of municipal solid waste. Two laboratory-scale acid-phase digesters and three laboratory-scale methane-phase digesters were employed in order to determine the impacts of SSO co-digestion with municipal sludges both with and without acid-phase digestion as a pretreatment step. Reactors were operated at 35 °C using volatile solids loading rates of 34.2-44.1 g VS/LR-day for acid-phase digesters and 1.2-2.4 1 g VS/LR-day for methane-phase digesters. Solids retention times ranging from 1.2 to 1.5 day and 20.7 to 23.2 days were employed for acid-phase and methane-phase digesters, respectively. VS destruction ranged from 62% to 67%, with reactors receiving SSO achieving higher VS destruction. Results also show that reactors receiving SSO were able to handle organic loading increases of at least 39% without showing signs of overloading. Microbial community analysis revealed that SSO had a noticeable impact on acid-phase digestion with Megasphaera emerging as the most abundant genus.

Microbial acceleration of aerobic pyrite oxidation at circumneutral pH.

Pyrite (FeS2 ) is the most abundant sulfide mineral on Earth and represents a significant reservoir of reduced iron and sulfur both today and in the geologic past. In modern environments, oxidative transformations of pyrite and other metal sulfides play a key role in terrestrial element partitioning with broad impacts to contaminant mobility and the formation of acid mine drainage systems. Although the role of aerobic micro-organisms in pyrite oxidation under acidic-pH conditions is well known, to date there is very little known about the capacity for aerobic micro-organisms to oxidize pyrite at circumneutral pH. Here, we describe two enrichment cultures, obtained from pyrite-bearing subsurface sediments, that were capable of sustained cell growth linked to pyrite oxidation and sulfate generation at neutral pH. The cultures were dominated by two Rhizobiales species (Bradyrhizobium sp. and Mesorhizobium sp.) and a Ralstonia species. Shotgun metagenomic sequencing and genome reconstruction indicated the presence of Fe and S oxidation pathways in these organisms, and the presence of a complete Calvin-Benson-Bassham CO2 fixation system in the Bradyrhizobium sp. Oxidation of pyrite resulted in thin (30-50 nm) coatings of amorphous Fe(III) oxide on the pyrite surface, with no other secondary Fe or S phases detected by electron microscopy or X-ray absorption spectroscopy. Rates of microbial pyrite oxidation were approximately one order of magnitude higher than abiotic rates. These results demonstrate the ability of aerobic microbial activity to accelerate pyrite oxidation and expand the potential contribution of micro-organisms to continental sulfide mineral weathering around the time of the Great Oxidation Event to include neutral-pH environments. In addition, our findings have direct implications for the geochemistry of modern sedimentary environments, including stimulation of the early stages of acid mine drainage formation and mobilization of pyrite-associated metals.

Amplifying the benefits of agroecology by using the right cultivars.

Tropical soils are particularly vulnerable to fertility losses due to their low capacity to retain organic matter and mineral nutrients. This urges the development of new agricultural practices to manage mineral nutrients and organic matter in a more sustainable way while relying less on fertilizer inputs. Two methods pertaining to ecological engineering and agroecology have been tested with some success: (1) the addition of biochar to the soil, and (2) the maintenance of higher earthworm densities. However, modern crop varieties have been selected to be adapted to agricultural practices and to the soil conditions they lead to and common cultivars might not be adapted to new practices. Using rice as a model plant, we compared the responsiveness to biochar and earthworms of five rice cultivars with contrasted selection histories. These cultivars had contrasted responsivenesses to earthworms, biochar, and the combination of both. The mean relative increase in grain biomass, among all treatments and cultivars, was 94% and 32%, respectively, with and without fertilization. Choosing the best combination of cultivar and treatment led to a more than fourfold increase in this mean benefit (a 437% and a 353% relative increase in grain biomass, respectively, with and without fertilization). Besides, the more rustic cultivar, a local landrace adapted to diverse and difficult conditions, responded the best to earthworms in terms of total biomass, while a modern common cultivar responded the best in term of grain biomass. This suggests that cultivars could be selected to amplify the benefit of biochar- and earthworm-based practices. Overall, selecting new cultivars interacting more closely with soil organisms and soil heterogeneity could increase agriculture sustainability, fostering the positive feedback loop between soils and plants that has evolved in natural ecosystems.

Development of a solar-powered microbial fuel cell.

AIMS: To understand factors that impact solar-powered electricity generation by Rhodobacter sphaeroides in a single-chamber microbial fuel cell (MFC). METHODS AND RESULTS: The MFC used submerged platinum-coated carbon paper anodes and cathodes of the same material, in contact with atmospheric oxygen. Power was measured by monitoring voltage drop across an external resistance. Biohydrogen production and in situ hydrogen oxidation were identified as the main mechanisms for electron transfer to the MFC circuit. The nitrogen source affected MFC performance, with glutamate and nitrate-enhancing power production over ammonium. CONCLUSIONS: Power generation depended on the nature of the nitrogen source and on the availability of light. With light, the maximum point power density was 790 mW m(-2) (2.9 W m(-3)). In the dark, power output was less than 0.5 mW m(-2) (0.008 W m(-3)). Also, sustainable electrochemical activity was possible in cultures that did not receive a nitrogen source. SIGNIFICANCE AND IMPACT OF THE STUDY: We show conditions at which solar energy can serve as an alternative energy source for MFC operation. Power densities obtained with these one-chamber solar-driven MFC were comparable with densities reported in nonphotosynthetic MFC and sustainable for longer times than with previous work on two-chamber systems using photosynthetic bacteria.

Characterization of two ammonia-oxidizing bacteria isolated from reactors operated with low dissolved oxygen concentrations.

AIMS: To obtain ammonia-oxidizing bacterial (AOB) strains inhabiting low dissolved oxygen (DO) environments and to characterize them to better understand their function and ecology. METHODS AND RESULTS: Using a serial dilution method, two AOB strains (ML1 and NL7) were isolated from chemostat reactors operated with low DO concentrations (0.12-0.24 mg l(-1)). Phylogenetically, strains ML1 and NL7 are affiliated to AOB within the Nitrosomonas europaea and Nitrosomonas oligotropha lineages, respectively. Kinetically, strain ML1 had high affinity for oxygen (0.24 +/- 0.13 mg l(-1)) and low affinity for ammonia (1.62 +/- 0.97 mg N l(-1)), while strain NL7 had high affinity for ammonia (0.48 +/- 0.35 mg l(-1)), but a surprisingly low affinity for oxygen (1.22 +/- 0.43 mg l(-1)). A co-culture experiment was used to iteratively estimate decay constants for both strains. CONCLUSIONS: The results indicated that AOB without high affinity for oxygen may have other mechanisms to persist in low DO environments, with high affinity for ammonia being important. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides a method to determine AOB growth kinetic parameters without assuming or neglecting decay constant. And, this is the first report on oxygen affinity constant of a N. oligotropha strain.

Reproductive biology of Oreochromis niloticus (Perciformes: Cichlidae) at Emiliano Zapata dam, Morelos, Mexico

The reproductive season of tilapia was studied by monthly samplings at Emiliano Zapata dam, Morelos State, Mexico. From February 1999 through February 2000 a sample of 50 fish was taken from the commercial catch (castnet, 6.5 cm of mesh size). The observed sex ratio was 1:1.29 (females:males) (2=10.26; p<0.05). The tilapia reached maturity at 151.3 mm (females) and 152.0 mm (males) of total length. Rainy (August) and dry (February) seasons were determined as the breeding period. Fecundity variation was better correlated with length (r=0.7473; p<0.002) than with weight (r=0.7395; p<0.002). The fecundity ranged between 243 and 847 oocytes per fish, with egg diameter from 300 to 3 700 µm. Intensive breeding activity in August and February coincide with phytoplankton biomass increase

Se analizó la biología reproductiva de la tilapia en la presa Emiliano Zapata, Morelos, México. Para esto se realizaron muestreos de febrero 1999 a febrero 2000. Se tomaron 50 organismos mensuales de la captura comercial obtenidos con una atarraya de 6.5 cm de luz de malla. La proporción sexual fue de1:1.29 hembras:machos (2=10.26; p<0.05). La madurez sexual se alcanza a los 151.3 mm (hembras) y a los 152.0 mm (machos) de longitud total. Se detectaron dos épocas de reproducción para la especie: durante la estación lluviosa (agosto) y durante la estación de secas (febrero). La fecundidad relativa presentó mayor correlación con la longitud (r=0.7473; p<0.002) que con el peso (r=0.7395; p<0.002). Por otra parte, el intervalo para la fecundidad osciló entre 243 y 847 ovocitos por pez, con diámetros de 300 a 3 700 µm. Asimismo, la actividad reproductiva de la especie en Agosto y Febrero, coincide con el incremento de biomasa fitoplanctónica

Reproductive biology of Oreochromis niloticus (Perciformes: Cichlidae) at Emiliano Zapata dam, Morelos, Mexico.

The reproductive season of tilapia was studied by monthly samplings at Emiliano Zapata dam, Morelos State, Mexico. From February 1999 through February 2000 a sample of 50 fish was taken from the commercial catch (castnet, 6.5 cm of mesh size). The observed sex ratio was 1:1.29 (females:males) (chi(2)=10.26; p<0.05). The tilapia reached maturity at 151.3 mm (females) and 152.0 mm (males) of total length. Rainy (August) and dry (February) seasons were determined as the breeding period. Fecundity variation was better correlated with length (r=0.7473: p<0.002) than with weight (r=0.7395; p<0.002). The fecundity ranged between 243 and 847 oocytes per fish, with egg diameter from 300 to 3 700 microm. Intensive breeding activity in August and February coincide with phytoplankton biomass increase.

Introduction to the IWA task group on biofilm modeling.

An International Water Association (IWA) Task Group on Biofilm Modeling was created with the purpose of comparatively evaluating different biofilm modeling approaches. The task group developed three benchmark problems for this comparison, and used a diversity of modeling techniques that included analytical, pseudo-analytical, and numerical solutions to the biofilm problems. Models in one, two, and three dimensional domains were also compared. The first benchmark problem (BM1) described a monospecies biofilm growing in a completely mixed reactor environment and had the purpose of comparing the ability of the models to predict substrate fluxes and concentrations for a biofilm system of fixed total biomass and fixed biomass density. The second problem (BM2) represented a situation in which substrate mass transport by convection was influenced by the hydrodynamic conditions of the liquid in contact with the biofilm. The third problem (BM3) was designed to compare the ability of the models to simulate multispecies and multisubstrate biofilms. These three benchmark problems allowed identification of the specific advantages and disadvantages of each modeling approach. A detailed presentation of the comparative analyses for each problem is provided elsewhere in these proceedings.

Comparing biofilm models for a single species biofilm system.

A benchmark problem was defined to evaluate the performance of different mathematical biofilm models. The biofilm consisted of heterotrophic bacteria degrading organic substrate and oxygen. Mathematical models tested ranged from simple analytical to multidimensional numerical models. For simple and more or less flat biofilms it was shown that analytical biofilm models provide very similar results compared to more complex numerical solutions. When considering a heterogeneous biofilm morphology it was shown that the effect of an increased external mass transfer resistance was much more significant compared to the effect of an increased surface area inside the biofilm.

Modelling a spatially heterogeneous biofilm and the bulk fluid: selected results from benchmark problem 2 (BM2).

The numerical simulation of mass transfer and conversion in spatially heterogeneous biofilms on the meso-scale requires an accurate description of the hydrodynamics in the biofilm systems and of spatial effects. This leads to systems of three-dimensional nonlinear partial differential equations that are numerically very expensive to solve and to data requirements that are not easy to meet. In this paper several modeling approaches to reduce the physical complexity and, hence, accelerate the computation are compared. They range from a mere reduction of dimensionality by lumping the problem along a secondary flow direction to global mass balances or empirical correlations, at the core of which a one-dimensional boundary value problem must be solved. It is found that even strongly simplified models can describe the qualitative behaviour of the model with regard to variations in the geometrical and hydrodynamic model parameters quite well. In order to obtain also quantitatively reliable results the hydrodynamics must be considered in an appropriate manner.

Results from the multi-species benchmark problem 3 (BM3) using two-dimensional models.

In addition to the one-dimensional solutions of a multi-species benchmark problem (BM3) presented earlier (Rittmann et al., 2004), we offer solutions using two-dimensional (2-D) models. Both 2-D models (called here DN and CP) used numerical solutions to BM3 based on a similar mathematical framework of the one-dimensional AQUASIM-built models submitted by Wanner (model W) and Morgenroth (model M1), described in detail elsewhere (Rittmann et al., 2004). The CP model used differential equations to simulate substrate gradients and biomass growth and a particle-based approach to describe biomass division and biofilm growth. The DN model simulated substrate and biomass using a cellular automaton approach. For several conditions stipulated in BM3, the multidimensional models provided very similar results to the 1-D models in terms of bulk substrate concentrations and fluxes into the biofilm. The similarity can be attributed to the definition of BM3, which restricted the problem to a flat biofilm in contact with a completely mixed liquid phase, and therefore, without any salient characteristics to be captured in a multidimensional domain. On the other hand, the models predicted significantly different accumulations of the different types of biomass, likely reflecting differences in the way biomass spread within the biofilm is simulated.

Simultaneous determination of bacterial viability and identity in biofilms using ethidium monoazide and fluorescent in situ hybridization.

A protocol for simultaneously interrogating bacterial viability and identity using in situ, culture-independent methods is described. Viability is assayed using ethidium monoazide (EMA) staining of cells with compromised membranes, and identity is determined using fluorescent in situ hybridization (FISH). Experiments with planktonic cultures were used to demonstrate the compatibility of EMA staining and FISH after covalently bonding EMA to nucleic acids by photoreaction. Applications to biofilm samples showed that diffusion limitations in the biofilm matrix were not problematic and that effective discrimination of viable target cells within a mixed microbial community was possible.

Presence of Rhodocyclus in a full-scale wastewater treatment plant and their participation in enhanced biological phosphorus removal.

The objective of this research was to assess the relevance of organisms related to Rhodocyclus in enhanced biological phosphorus removal in full-scale wastewater treatment plants. The presence of these organisms in full-scale plants was first confirmed by fluorescent in situ hybridization. To address which organisms were involved in phosphorus removal, a method was developed which selected polyphosphate-accumulating organisms from activated sludge samples by DAPI staining and flow cytometry. Sorted samples were characterized using fluorescent in situ hybridization. The results of these analyses confirmed the presence of organisms related to Rhodocyclus in full-scale wastewater treatment plants and supported the involvement of these organisms in enhanced biological phosphorus removal. However, a significant fraction of the polyphosphate-accumulating organisms were not related to Rhodocyclus.

Molecular analysis of ammonia-oxidizing bacterial populations in aerated-anoxic orbal processes.

Aerated-anoxic processes operate under the principle that small additions of oxygen to an anoxic reactor induce simultaneous nitrification and denitrification. In these systems, ammonia oxidation in the anoxic zone can easily account for 30-50% of the total nitrification in the reactor, even though the dissolve oxygen concentration is usually below detection limit. To investigate whether the nitrification efficiency in aerated-anoxic processes was due to the presence of specialized ammonia-oxidizing bacteria (AOB), an analysis of the AOB population in an aerated-anoxic Orbal process and a conventional nitrogen removal process was carried out using phylogenetic analyses based on the ammonia monooxygenase A (amoA) gene. Terminal restriction fragment length polymorphism (TRFLP) analyses revealed that Nitrosospira-like organisms were one of the major contributors to ammonia oxidation in a full-scale aerated-anoxic Orbal reactor. However, the relative populations of Nitrosospira-like and Nitrosomonas-like AOB were not constant and appeared to have seasonal variability. Cloning and sequence comparison of amoA gene fragments demonstrated that most of the AOB in the aerated-anoxic Orbal process belonged to the Nitrosospira sp. and Nitrosomonas oligotropha lineages. The abundance of Nitrosospira-like organisms in aerated-anoxic reactors is significant, since this group of AOB has not been usually associated with nitrification in wastewater treatment plants.

Transformation of 2,4,6-trinitrotoluene by purified xenobiotic reductase B from Pseudomonas fluorescens I-C.

The enzymatic transformation of 2,4,6-trinitrotoluene (TNT) by purified XenB, an NADPH-dependent flavoprotein oxidoreductase from Pseudomonas fluorescens I-C, was evaluated by using natural abundance and [U-(14)C]TNT preparations. XenB catalyzed the reduction of TNT either by hydride addition to the aromatic ring or by nitro group reduction, with the accumulation of various tautomers of the protonated dihydride-Meisenheimer complex of TNT, 2-hydroxylamino-4,6-dinitrotoluene, and 4-hydroxylamino-2, 6-dinitrotoluene. Subsequent reactions of these metabolites were nonenzymatic and resulted in predominant formation of at least three dimers with an anionic m/z of 376 as determined by negative-mode electrospray ionization mass spectrometry and the release of approximately 0.5 mol of nitrite per mol of TNT consumed. The extents of the initial enzymatic reactions were similar in the presence and in the absence of O(2), but the dimerization reaction and the release of nitrite were favored under aerobic conditions or under anaerobic conditions in the presence of NADP(+). Reactions of chemically and enzymatically synthesized and high-pressure liquid chromatography-purified TNT metabolites showed that both a hydroxylamino-dinitrotoluene isomer and a tautomer of the protonated dihydride-Meisenheimer complex of TNT were required precursors for the dimerization and nitrite release reactions. The m/z 376 dimers also reacted with either dansyl chloride or N-1-naphthylethylenediamine HCl, providing evidence for an aryl amine functional group. In combination, the experimental results are consistent with assigning the chemical structures of the m/z 376 species to various isomers of amino-dimethyl-tetranitrobiphenyl. A mechanism for the formation of these proposed TNT metabolites is presented, and the potential enzymatic and environmental significance of their formation is discussed.