Ecology and distribution of Thaumarchaea in the deep hypolimnion of Lake Maggiore

Ammonia-oxidizing Archaea (AOA) play an important role in the oxidation of ammonia in terrestrial, marine, and geothermal habitats, as confirmed by a number of studies specifically focused on those environments. Much less is known about the ecological role of AOA in freshwaters. In order to reach a high resolution at the Thaumarchaea community level, the probe MGI-535 was specifically designed for this study and applied to fluorescence in situ hybridization and catalyzed reporter deposition (CARD-FISH) analysis. We then applied it to a fine analysis of diversity and relative abundance of AOA in the deepest layers of the oligotrophic Lake Maggiore, confirming previous published results of AOA presence, but showing differences in abundance and distribution within the water column without significant seasonal trends with respect to Bacteria. Furthermore, phylogenetic analysis of AOA clone libraries from deep lake water and from a lake tributary, River Maggia, suggested the riverine origin of AOA of the deep hypolimnion of the lake

modeling early time dynamics of relativistic heavy ion collisions

We studied isotropization and thermalization of the quark-gluon plasma produced by decaying color-electric flux tubes created at the very early stages of relativistic heavy ion collisions. We coupled the dynamical evolution of the initial field, which decays to a plasma by the Schwinger mechanism, to the dynamics of the many particles system produced by the decay. The evolution of such a system is described by relativistic transport theory at fixed values of the viscosity over entropy density ratio. Within a single self-consistent calculation scheme we computed quantities which serve as indicators of the equilibration of the plasma for a 1+1 dimensional expanding geometry. We find that the initial color-electric field decays within 1 fm/c and particles production occurs in less than 1 fm/c; however, in the case of large viscosity oscillations of the field appear along the entire time evolution of the system, affecting also the behaviour of the ratio between longitudinal and transverse pressure. In case of small viscosity we find that the isotropization time is about 0.8 fm/c and the thermalization time is about 1 fm/c, in agreement with the common lore of hydrodynamic approaches

New method to assess teh pozzolanic reactivity of mineral admixtures by measn of pH and electrical conductivity measurements in lime: pozzolan suspensions

A very simple method based on electrical conductivity and pH measurements was proposed for assessing reactivity of pozzolans. Calcium hydroxide:pozzolan water suspensions were monitored by means of measurements of electrical conductivity and pH values. In these suspensions, Ca(OH)2 in solid state was initially present, being them, thus, saturated in this reagent. Three testing temperatures were selected (40, 50 and 60 °C). In the experiments carried out, calcium hydroxide was suspended in deionized water for yielding a lime saturated suspension. The addition of siliceous pozzolan (two types of rice husk ash RHA and two types of densified silica fume DSF were tested) to the saturated lime suspension can produce the unsaturation of the system, depending on the testing time, testing temperature and reactivity of pozzolan. When unsaturation was reached, the loss of electrical conductivity was higher than 30% and the variation of pH was higher than 0.15 units. These threshold values were selected for characterizing the reactivity of pozzolans by means of a proposed template, classifying the pozzolan in three different reactivity levels.Mitsuuchi Tashima, M.; Soriano Martinez, L.; Monzó Balbuena, JM.; Borrachero Rosado, MV.; Akasaki, JL.; Paya Bernabeu, JJ. (2014). New method to assess teh pozzolanic reactivity of mineral admixtures by measn of pH and electrical conductivity measurements in lime: pozzolan suspensions. Materiales de Construcción. 64(316):32-44. doi:10.3989/mc.2014.00914S324464316Schneider, M., Romer, M., Tschudin, M., & Bolio, H. (2011). Sustainable cement production—present and future. Cement and Concrete Research, 41(7), 642-650. doi:10.1016/j.cemconres.2011.03.019Altmann, F., & Mechtcherine, V. (2013). Durability design strategies for new cementitious materials. Cement and Concrete Research, 54, 114-125. doi:10.1016/j.cemconres.2013.08.008Shi, C., Jiménez, A. F., & Palomo, A. (2011). New cements for the 21st century: The pursuit of an alternative to Portland cement. Cement and Concrete Research, 41(7), 750-763. doi:10.1016/j.cemconres.2011.03.0164. Payá, J. (2012) La "transmutación" sostenible de los residuos para nuevas materias primas en el ámbito del concreto. Dyna 79, 38–47.Donatello, S., Freeman-Pask, A., Tyrer, M., & Cheeseman, C. R. (2010). Effect of milling and acid washing on the pozzolanic activity of incinerator sewage sludge ash. Cement and Concrete Composites, 32(1), 54-61. doi:10.1016/j.cemconcomp.2009.09.002Soriano, L., Monzó, J., Bonilla, M., Tashima, M. M., Payá, J., & Borrachero, M. V. (2013). Effect of pozzolans on the hydration process of Portland cement cured at low temperatures. Cement and Concrete Composites, 42, 41-48. doi:10.1016/j.cemconcomp.2013.05.0077. Villar-Coci-a, E.; Frías, M.; Valencia-Morales, E.; Rojas, M.I.S. (2005) Validation of a kinetic-diffusive model to characterize pozzolanic reaction kinetics in sugar cane straw-clay ash/lime systems. Mater. Construcc. 55 [278], 29–40.8. Cruz, J.M.; Payá, J.; Lalinde, L.F.; Fita, I.C. (2011) Evaluation of electric properties of cement mortars containing pozzolans. Mater. Construcc. 61 [301], 7–26.Luxán, M. P., Madruga, F., & Saavedra, J. (1989). Rapid evaluation of pozzolanic activity of natural products by conductivity measurement. Cement and Concrete Research, 19(1), 63-68. doi:10.1016/0008-8846(89)90066-5Payá, J., Borrachero, M. ., Monzó, J., Peris-Mora, E., & Amahjour, F. (2001). Enhanced conductivity measurement techniques for evaluation of fly ash pozzolanic activity. Cement and Concrete Research, 31(1), 41-49. doi:10.1016/s0008-8846(00)00434-8Villar-Cociña, E., Valencia-Morales, E., González-Rodrı́guez, R., & Hernández-Ruı́z, J. (2003). Kinetics of the pozzolanic reaction between lime and sugar cane straw ash by electrical conductivity measurement: A kinetic–diffusive model. Cement and Concrete Research, 33(4), 517-524. doi:10.1016/s0008-8846(02)00998-5Frías, M., Villar-Cociña, E., Sánchez de Rojas, M. I., & Valencia-Morales, E. (2005). The effect that different pozzolanic activity methods has on the kinetic constants of the pozzolanic reaction in sugar cane straw-clay ash/lime systems: Application of a kinetic–diffusive model. Cement and Concrete Research, 35(11), 2137-2142. doi:10.1016/j.cemconres.2005.07.005Sinthaworn, S., & Nimityongskul, P. (2009). Quick monitoring of pozzolanic reactivity of waste ashes. Waste Management, 29(5), 1526-1531. doi:10.1016/j.wasman.2008.11.010Payá, J., Monzó, J., Borrachero, M. ., Mellado, A., & Ordoñez, L. . (2001). Determination of amorphous silica in rice husk ash by a rapid analytical method. Cement and Concrete Research, 31(2), 227-231. doi:10.1016/s0008-8846(00)00466-xMartínez-Velandia, D., Payá, J., Monzó, J., & Borrachero, M. V. (2011). Effect of sonication on the reactivity of silica fume in Portland cement mortars. Advances in Cement Research, 23(1), 23-31. doi:10.1680/adcr.8.00027Tashima, M. M., Fioriti, C. F., Akasaki, J. L., Bernabeu, J. P., Sousa, L. C., & Melges, J. L. P. (2012). Cinza de casca de arroz (CCA) altamente reativa: método de produção e atividade pozolânica. Ambiente Construído, 12(2), 151-163. doi:10.1590/s1678-86212012000200010Payá, J., Monzó, J., Borrachero, M. V., Peris-Mora, E., & Amahjour, F. (2000). Mechanical treatment of fly ashes. Cement and Concrete Research, 30(4), 543-551. doi:10.1016/s0008-8846(00)00218-

Community shift of ammonia-oxidizing bacteria along an anthropogenic pollution gradient from the Pearl River Delta to the South China Sea

The phylogenetic diversity and abundance of ammonia-oxidizing beta-proteobacteria (beta-AOB) was analyzed along an anthropogenic pollution gradient from the coastal Pearl River Delta to the South China Sea using the ammonia monooxygenase subunit A (amoA) gene. Along the gradient from coastal to the open ocean, the phylogenetic diversity of the dominant genus changed from Nitrosomonas to Nitrosospira, indicating the niche specificity by these two genera as both salinity and anthropogenic influence were major factors involved. The diversity of bacterial amoA gene was also variable along the gradient, with the highest in the deep-sea sediments, followed by the marshes sediments and the lowest in the coastal areas. Within the Nitrosomonas-related clade, four distinct lineages were identified including a putative new one (A5-16) from the different sites over the large geographical area. In the Nitrosospira-related clade, the habitat-specific lineages to the deep-sea and coastal sediments were identified. This study also provides strong support that Nitrosomonas genus, especially Nitrosomonas oligotropha lineage (6a) could be a potential bio-indicator species for pollution or freshwater/wastewater input into coastal environments. A suite of statistical analyses used showed that water depth and temperature were major factors shaping the community structure of beta-AOB in this study area

Niche differentiation between ammonia-oxidizing bacteria in aquatic environments

The aim of the studies presented in this thesis was the search for niche differentiation between the ammonia-oxidizing bacteria in aquatic environments. Ammonia-oxidizing bacteria are chemolitho-autotrophic microorganisms responsible for the first, mostly rate-limiting step of the nitrification process, i.e. the conversion of ammonia into nitrite. The recent development of molecular techniques had overcome the difficulties inherent to the classic cultivation-based methods applied to these slow-growing bacteria. Finally, a large diversity of ammonia-oxidizing bacteria has been uncovered in several aquatic environments. However, only a few studies focused on niche differentiation between these bacteria within the same estuarine or freshwater environment. The studies reported in this thesis demonstrated the existence of an intriguing niche differentiation between ammonia-oxidizing bacteria driven by different factors, such as ammonia and oxygen availability, salinity, tidal regime, physical-chemical characteristics of the substrate for the biofilm formation and anthropogenic influences. In particular, in shallow freshwater lakes dominated by submerged macrophytes ammonia-oxidizing bacteria appeared to utilize the epiphyton as a niche in addition to the benthic and pelagic compartments (Chapters II and III). The molecular detection of ammonia-oxidizing bacteria on the leaves of submerged macrophytes, like Potamogeton pectinatus, is the first time ever to be reported (Chapter II and III). Diversity, numbers and activity of benthic, pelagic and epiphytic ammonia-oxidizing bacteria was influenced by the characteristics of both the compartments and the lakes in which the samples were collected (Chapter III). Ammonia-oxidizing bacteria showed higher diversity, numbers and activity in the benthic compartment in comparison to the pelagic compartment (Chapter III). Members of the Nitrosomonas oligotropha lineage dominated the pelagic compartment and were present in the benthic section together with members of the clusters 0 and 3 of the Nitrosospira lineage. The epiphyton was colonized by both pelagic and benthic ammonia-oxidizing bacteria. The dynamics of colonization of the epiphyton by benthic and pelagic ammonia-oxidizing bacteria were investigated in a microcosm experiment (Chapter IV). Results showed that benthic ammonia oxidizers colonized the surface of the macrophytes both during the sprouting of the tubers and the resuspension of sediment particles. Moreover, being attached to the macrophytes surface appeared to be favorable for pelagic species that were otherwise not detectable in their original compartment. Restoration procedures applied to the lakes in the past at different intensities, appeared to influence the overall fitness of ammonia-oxidizing bacteria negatively (Chapter III). Briefly, the best restored lake, i.e. Lake Nuldernauw, nowadays colonized by a Charophytes meadow showed the lowest diversity, numbers and potential activity of ammonia-oxidizing cells. The influence of anthropogenic inputs on the niche differentiation of ammonia-oxidizing bacteria was also shown in a study along a freshwater-estuarine gradient in addition to the effects of salinity as well as ammonia and oxygen availability (Chapter V). Salinity showed to be a steering factor for the succession from salt-sensitive to salt-tolerant ammonia-oxidizing species in freshwater sediment during a microcosm experiment with controlled environmental perturbations (Chapter VI). Finally, the studies presented in this thesis contributed to the knowledge on the niche differentiation between ammonia-oxidizing bacteria in freshwater and estuarine ecosystems by describing the epiphyton of submerged macrophytes as a novel niche for ammonia oxidizers and by describing the response of these bacteria to natural and anthropogenic environmental perturbations

Effects of substratum on the diversity and stability of ammonia-oxidising communities in a constructed wetland used for wastewater treatment

Aim: To study the relationship between the nature of the substratum and the diversity and stability of the ammonia-oxidizing microbial community in a constructed wetland for the treatment of wastewaters. Methods and Results: Samples have been taken the year around from sections of the wetland filled with different substrata. When present, the root zones of the helophyte Phragmites australis were also sampled. The diversity of the ammonia-oxidizing community was established by a coupled PCR–DGGE method based on the 16s rRNA gene. Averaged over the seasons, no large differences in community composition were observed between the different substrata, although the section with zeolite always showed t Conclusions: Although the ammonia-oxidizing communities did not differ significantly between the different sections of the constructed wetland, the characteristics of zeolite were most appropriate to accommodate a stable and active community of ammonia-oxidizing bacteria. The presence of the helophyte had no effect on the diversity and stability of the ammonia-oxidizing community. Significance and Impact of the Study: It has been shown that substrata used in constructed wetlands made no distinction between ammonia-oxidizing strains in relation to attachment. However, zeolite had the best performance with respect to activity over the season

Effects of substratum on the diversity and stability of ammonia-oxidising communities in a constructed wetland used for wastewater treatment

Aim: To study the relationship between the nature of the substratum and the diversity and stability of the ammonia-oxidizing microbial community in a constructed wetland for the treatment of wastewaters. Methods and Results: Samples have been taken the year around from sections of the wetland filled with different substrata. When present, the root zones of the helophyte Phragmites australis were also sampled. The diversity of the ammonia-oxidizing community was established by a coupled PCR–DGGE method based on the 16s rRNA gene. Averaged over the seasons, no large differences in community composition were observed between the different substrata, although the section with zeolite always showed t Conclusions: Although the ammonia-oxidizing communities did not differ significantly between the different sections of the constructed wetland, the characteristics of zeolite were most appropriate to accommodate a stable and active community of ammonia-oxidizing bacteria. The presence of the helophyte had no effect on the diversity and stability of the ammonia-oxidizing community. Significance and Impact of the Study: It has been shown that substrata used in constructed wetlands made no distinction between ammonia-oxidizing strains in relation to attachment. However, zeolite had the best performance with respect to activity over the seasons

Epiphyton as a Niche for Ammonia-Oxidizing Bacteria: Detailed Comparison with Benthic and Pelagic Compartments in Shallow Freshwater Lakes▿

Next to the benthic and pelagic compartments, the epiphyton of submerged macrophytes may offer an additional niche for ammonia-oxidizing bacteria in shallow freshwater lakes. In this study, we explored the potential activities and community compositions of ammonia-oxidizing bacteria of the epiphytic, benthic, and pelagic compartments of seven shallow freshwater lakes which differed in their trophic status, distribution of submerged macrophytes, and restoration history. PCR-denaturing gradient gel electrophoresis analyses demonstrated that the epiphytic compartment was inhabited by species belonging to cluster 3 of the Nitrosospira lineage and to the Nitrosomonas oligotropha lineage. Both the ammonia-oxidizing bacterial community compositions and the potential activities differed significantly between compartments. Interestingly, both the ammonia-oxidizing bacterial community composition and potential activity were influenced by the restoration status of the different lakes investigated