Inaug.-Diss.--Königsberg.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2006 / Includes bibliographical references.

Nitrification is a central part of the nitrogen cycle, whereby the most reduced form, ammonia, is converted to the most oxidised form, nitrate via nitrite. The first step is performed by ammonia oxidising bacteria (AOB) and archaea (AOA), with the second step performed by nitrite oxidising bacteria (NOB). Although both groups are closely associated in nature, ammonia oxidisers have received more attention compared to NOB as ammonia oxidation is considered the rate-limiting step. Nitrobacter and Nitrospira are two important groups of soil NOB. To determine whether there are specific associations of AOA or AOB with certain NOB, the effect of organic and inorganic ammonia sources was tested by adding glutamate or ammonium sulphate to soil together with either 5% 12CO2 or 13CO2 to determined autotrophic growth by DNA-SIP. The results demonstrated that while the various ammonia and nitrite oxidisers responded differently, there was no direct evidence of specific coupled interactions. The effects of soil pH on Nitrobacter and Nitrospira was then investigated in a long-term pH gradient in an agricultural field. The results demonstrated that Nitrospira abundance was lower in acidic soils, whereas Nitrobacter abundance remained equally or more abundant. pH also influenced the relative distribution of Nitrobacter and Nitrospira populations, with distinct community structures at both high and low pH. The interaction of AOA and NOB was further investigated in a co-culture experiment, and demonstrated that the removal of nitrite and free nitrous acid NOB enhanced both rates and amounts of ammonia oxidised, indicating that in acidic environments these relationships may be particularly critical. Finally, the use of the compound PTIO was investigated for potential use in elucidating specific relationships between AOA and NOB. Results demonstrated a lack of specificity for the target group, and was unstable in soil, and therefore its use in soil should proceed with caution.

Magister Scientiae - MSc / The major objective of this study was to investigate soil ammonia-oxidizing bacterial diversity and composition associated with plant roots of Proteaceae plants and to compare it with non-plant associated soil. / South Africa

A total of 200 Rhizobium meliloti isolates were sampled from alfalfa (Medicago sativa L.) nodules in five uninoculated fields throughout Arizona. Dominant strains (≥ 20% nodule occupancy at each site) were identified using plasmid profile analysis and intrinsic antibiotic resistance patterns. The major dominant strains and a commercial strain (102F77b) were evaluated for their N fixing effectiveness in a Leonard jar study. All strains were highly effective, and no significant differences were found (p ≥ 0.05) in shoot weight, root weight, nodule weight, acetylene reduction and total N content among the strain treatments. These effective dominant R. meliloti strains indigenous to Arizona soil probably contribute to the state's high alfalfa yield. Furthermore, indigenous strains AZTCYJ, AZSC, and AZY have potential as inoculants for arid lands due to their high effectiveness and unique resistances to extreme abiotic stresses present in arid land soils.

Wastewater treatment plants (WWTPs) are required to remove ammonium (NH4+) from wastewater due to its oxygen demand and toxicity to the aquatic organisms. Ammonium is removed in the activated sludge treatment system by nitrification and denitrification processes. Nitrification is the oxidation of NH4+ to nitrate (NO3-) by autotrophic nitrifying bacteria which use carbon dioxide (CO2) as a carbon source for growth. These bacteria grow slowly with low nitrification rates limiting WWTPs capacity. In this research it was hypothesized that supplying higher concentrations of CO2 during aeration increases nitrification rates, resulting in a reduction of the solids retention time (SRT). This hypothesis was tested with two lab-scale sequencing batch reactors seeded with sludge from a full-scale activated sludge WWTP and fed synthetic wastewater. The control reactor was aerated with regular air (0.03% CO2) and the experimental reactor was aerated with air containing 1% CO2. Ammonium and NO3- were measured online to determine the nitrification rates. Samples for solids and chemical oxygen demand (COD) determination were collected to evaluate the system performance. Supplying CO2 to the experimental reactor throughout the entire react cycle resulted in proliferation of filamentous bacteria, poor settling, and washout of the biomass. However, nitrate formation rates in the experimental reactor were 3 times higher than the control before washout occurred. In a subsequent experiment, CO2 was supplied to the experimental reactor only during the last 5 hours of the cycle, resulting in excellent settling and nitrification rates 6 times higher than in the control. A confirmatory experiment was conducted that lowered the SRT from 8 days to 6, 4, and 2 days. Nitrate formation rates were up to 12 times higher in the experimental reactor compared to the control, with an average of 4 times higher. Additionally, the sludge volume index (SVI) suggested a positive impact of CO2 on settling performance. No impact of CO2 on COD removal was observed. The results obtained suggest a positive effect of CO2 on the nitrate formation and settling performance in the activated sludge system, indicating that nitrification can be achieved at low SRTs which might optimize WWTPs capacity.

Graduation date: 1996

Bibliography: leaves 183-202 / xxiv, 202 leaves, [46] leaves of plates : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Agricultural Biochemistry, Waite Agricultural Research Institute, 1984

Orientador: Silvio José Bicudo / Coorientador: Rogério Peres Soratto / Banca: Marcio Christian S. Domingues / Banca: Priscila Gonzales Figueiredo / Banca: Carlos Jorge da Silva / Banca: Luciano Soares de Souza / Resumo: O triticum aestivum é uma espécie de ciclo anual, pertencente à família Poaceae. Cultivado em regiões de climas subtropical e temperado, ocupa a segunda maior área plantada no mundo. Para obtenção de altas produtividade dentre outros cuidados, é essencial o fornecimento de nutrientes na quantidade demandada pelas cultivares de alto potencial produtivo, com destaque para o nitrogênio (N). A fixação biológica de nitrogênio é realizada por microrganismos simbióticos associados com raízes das plantas. Entre os microrganismos simbióticos que fixam nitrogênio associados com raízes de plantas, destacam-se os do gênero Azospirillum brasilense. O objetivo no presente trabalho foi avaliar a eficiência do uso da inoculação Azospirillum brasilense no desenvolvimento e componentes produtivos da cultura do trigo. O estudo foi dividido em dois experimentos sendo o primeiro em ambiente protegido e o segundo em ambiente não protegido, ambos na Faculdade de Ciências Agronômicas - Universidade Estadual Paulista "Júlio de Mesquita Filho", Campus de Botucatu, SP, no ano agrícola 2013. O delineamento utilizado foi o de blocos inteiramente casualizados para ambiente protegido e blocos casualizados para ambiente não protegido, com 10 tratamentos em esquema fatorial 3x3+1. Sendo os tratamentos compostos pelo uso de duas estirpes (Ab-V5 e Ab-V6) isoladamente e em combinação das mesmas (Ab-V5+Ab-V6), todos aplicados em três concentrações 65, 130 e 195 milhões de unidades formadoras de colônia (UFC) de... / Abstract: Triticum aestivum is a yearly crop species belonging to the Poaceae family. It is cultivated in regions with subtropical and temperate climate, and takes up the second largest planted area in the world. Nutrient provision in the demanded amount by high productive potential cultivars, mainly nitrogen (N), is essential to obtain high productivity. The biological fixation of nitrogen is done by symbiotic microorganisms associated with plan roots. Azospirillum brasilense is one of the genera in which the symbiotic microorganisms fixate nitrogen associated with plant roots. This study aimed to evaluate the agronomical efficiency of Azospirillum brasilense inoculation on the growth and productive components of wheat cultivation. The study was divided into two experiments: the fist protected environment, and the second non-protected environment conditions, both in the School of Agriculture - Universidade Estadual Paulista "Júlio de Mesquita Filho", Campus of Botucatu, SP, Brazil, during 2013 crop year. The experiment had completely randomized block design for the fist experiment in protected environment, and random blocks for the second experiment in non-protected environment, with 10 treatments in 3x3+1 factorial scheme. The treatments consisted of two separate (V5 and V6) and combined (V5+V6) stocks and three concentrations (65, 130 and 195 million UFC of bacteria) were applied. The control treatment had no bacterial inoculation. For the protected environment, each experimental plot consisted of plants cultivated in an asbestos recipient with the following dimensions: 0.50 m of height, 0.88 m of width and 1.05 m of length, and 0.462 m3 of soil. Seven 0.88-m rows with 0.15 m spacing and 40 seeds per meter were utilized. In the field experiment, the experimental plot consisted of ten 2.0-m rows with 0.17 m spacing and 45 seeds per meter. For both experiments, the seeding density was 266 seeds m2, aiming ... / Doutor

O lançamento de compostos nitrogenados em corpos d’água pode resultar em problemas ambientais, sendo assim tratar águas residuárias, como o esgoto sanitário com o objetivo de remover não apenas matéria orgânica, mas tambémnitrogênio tem sido objeto de estudo há algumas décadas. O objetivo deste trabalho foi avaliar o desempenho de um reator de leito estruturado e fluxo contínuo, com recirculação, na remoção de matéria orgânica e nitrogênio presente em esgoto sanitário, sob diferentes ciclos de Aeração intermitente (AI) e avaliar a influência destes ciclos no desenvolvimento de bactérias nitrificantes (Bactérias Oxidadoras de Amônia – BOA e Bactérias Oxidadoras de Nitrito – BON) e desnitrificantes (DESN) aderidas (Material Suporte - MS) e em suspensão (Efluente – EF e Lodo – LD). O reator utilizado possuía volume útil de 9,4 L. Como material suporte (MS) foi utilizado espuma de poliuretano, cortada e fixada em hastes de PVC. Foram trabalhadas 3 fases de aeração (AE) e não aeração (AN) com diferentes tempos: Fase 1 (4 h AE/ 2 h AN); Fase 2 (2 h AE/ 1 h AN) e Fase 3 (2 h AE/ 2 h AN). Durante todas as fases o tempo de detenção hidráulico foi mantido em 16 h e o efluente recirculado a uma vazão de 3 vezes a vazão afluente. Foram analisados: pH, alcalinidade total, temperatura, Demanda Química de Oxigênio (DQO), Demanda Bioquímica de Oxigênio (DBO), Nitrogênio Kjeldhl Total (NKT), N-amoniacal – N-NH4+, nitrito- N-NO2 e nitrato- N-NO3. A concentração das BOA, BON e DESN foi determinada utilizando o Número Mais Provável.gSSV-1 (NMP.gSSVmL-1). Na Fase 1 o percentual de remoção de NKT, N-NH4+ e NT foi de 76±10%, 70±21% e 67±10% respectivamente. Na Fase 2 de 80±15% de remoção de NKT, 86±15% de N-NH4+ e 68±9% de remoção de NT e na Fase 3 de 58±20%, 72±28% e 41±6% de NKT, N-NH4+ e NT, respectivamente. A eficiência de desnitrificação nas 3 fases foi acima de 70%, indicando que no reator ocorreu o processo de Nitrificação e desnitrificação Simultânea (NDS). Os percentuais de remoção de DQOT foram de 88%±4 na Fase 1, 94%±7 na Fase 2 e 90%±11 na Fase 3. A ANOVA multivariada aplicada ao NMP.gSSV-1, indicou que houve diferença significativa (F: 20,2; p-valor <0,01) entre a concentração dos organismos analisados nos diferentes ciclos de AI. Porém as diferenças entre os NMP.gSSV-1 não depende apenas de fatores isolados e sim de quais meios, fases e grupos estão sendo analisados. Dos resultados conclui-se que o sistema foi eficiente em termos de remoção de nitrogênio e matéria orgânica, e que a fase que apresentou a maior disponibilidade de Oxigênio Dissolvido (OD) e relação C/N (Fase 2), foi a que obteve as menores concentrações efluentes de matéria orgânica e N-NH4+. Apontasse que houve diferença significativa entre a concentração (NMP.gSSV-1) dos organismos analisados (BOA, BON e DESN), porém esta diferença não depende de fatores isolados e sim de quais meios (MS, EF ou LD, fases (1, 2 ou 3) e grupos (BOA, BON e DESN) está sendo considerado. / The release of nitrogen compounds in water bodies can result in many environmental problems, so treat wastewater, such as sewage in order to remove not only organic matter but also nitrogen has been studied a few decades. From the above, the objective of this study was to evaluate the performance of a structured bed reactor, continuous flow, with recirculation, in removing organic matter and nitrogen present in wastewater under different cycles of intermittent aeration (AI) and to evaluate the influence of these cycles in the development of nitrifying bacteria (Oxidizing Bacteria Ammonia - BOA and Bacteria Oxidizing Nitrite - BON) and denitrifying (DESN) adhered (Support Material - MS) and suspension (Effluent - EF and sludge - LD). The reactor used has usable volume of 9.4 L. As support materials (MS) polyurethane foam was used, cut and fixed in PVC rods. 3 were worked aeration phases (AE) and non-aeration (AN) at different stage: Stage 1 (4 h EA / AN 2H); Stage 2 (2H EA / AN 1 h) and Phase 3 (2H EA / AN 2 h). During all hydraulic detention time phases was kept at 16 h and the effluent recirculated at a rate of 3 times the inflow. Were analyzed: pH, total alkalinity, temperature, chemical oxygen demand (COD), Biochemical Oxygen Demand (BOD), nitrogen Kjeldhl Total (NKT), ammonia-N-N-NH4+, nitrito-N-NO2+andnitrato-NO3-. The concentration of BOA, BON and DESN was determined using the number More Provável.gSSV-1 (NMP.gSSV-1). In phase 1 the percentage removal NTK N-NH4+ and NT was 76±10%, 70±21% and 67±10% respectively. In Phase 2 80±15% of removel NKT, 86±15% of N-NH4+ e 68±9% of removel NT e na Fase 3 de 58±20%, 72±28% and 41±6% of NKT, N-NH4+ of NT, respectively. The denitrification efficiency in stage 3 was over 70%, indicating that occurred in the reactor the process of simultaneous nitrification and denitrification (NDS). DQOT the removal percentages were 88 ± 4% in Phase 1, 94 ± 7 in Phase 2 and 90± 11% in Phase 3. The multivariate ANOVA applied to NMP.gSSV-1, it indicated that there was significant (F: 20,2, p <0,01) between the analyzed concentration of organisms AI in different cycles, but the differences between NMP.gSSV-1 depends not only isolated factors but of which means, and phase groups being analysis. From the results it is concluded that the working system is efficient in terms of nitrogen removal and organic matter, and that the stage with the highest availability of Dissolved Oxygen (DO) and C/N ratio (Step 2), was the one obtained the lower concentrations of organic matter effluents and N-NH4+. Hinted that there was a significant difference between the concentration (NMP.100mL-1) of the analyzed organizations (BOA, BON and DESN), but this difference does not depend on factors alone but of which means (MS, EF or LD), stages (1, 2 or 3) and groups (BOA, BON and DESN) is being considered.