Lowland rice production is expanding throughout South-East Asia necessarily onto soils of poorer nutrient status with a resulting decrease in yields. An understanding of the nutrient status of the rice rhizosphere is essential for the development of appropriate management practices to increase rice yields. Phosphorus (P) deficiency is one aspect of rice nutrition. Increased rice root respiration and P uptake efficiency, and an increase in H$ sp{+}$ released from roots and enhanced solubility of calcium phosphates are two possible mechanisms of tolerance to low P levels. These mechanisms were evaluated but could not be used as single tests to differentiate among cultivars for tolerance to P deficiency. Phosphorus reactions in the soil may be confounded by the chemistry of iron (Fe). Iron and P interactions in the rice rhizosphere were investigated using a Philippine paddy soil. Root loss of oxygen (O$ sb2$) into the rhizosphere caused the oxidation of Fe$ sp{2+}$ and the concurrent release of H$ sp{+}$. Root release of H$ sp{+}$ from cation-anion uptake imbalances also contributed to the acidification of the rhizosphere. Accumulation of Fe$ sp{3+}$ was found next to the root plane. Depletion of acid-soluble P coincided with the zone of acidification. Rice plants were able to utilize the acid-soluble P fraction during growth.

Copies of author's previously published articles in pocket. / Bibliography: leaves 203-219. / xv, 219 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Main objectives of the thesis are: i. to verify a sealed chamber acid digestion technique for dissolution of plant material for total F analysis by a F ion selective electrode.--ii. to improve this technique for routine, rapid F analysis of plant material.--iii. to identify the inorganic ionic species of F which could be present in the soil solution.--iv. to determine which of these species are taken up by the plant root and those which are toxic to the plant. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1996

Made available in DSpace on 2014-11-10T11:09:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-03-21Bitstream added on 2014-11-10T11:58:20Z : No. of bitstreams: 1 000773460_20150321.pdf: 1008813 bytes, checksum: deba55d68e74350057c6c524e3e7c525 (MD5) Bitstreams deleted on 2015-03-27T11:50:06Z: 000773460_20150321.pdf,Bitstream added on 2015-03-27T11:50:37Z : No. of bitstreams: 1 000773460.pdf: 2111669 bytes, checksum: 1ac861fe88f214a1b60524e27ada9a8d (MD5) / Atualmente, avançadas tecnologias têm sido desenvolvidas para a exploração de fontes naturais pouco exploradas (exemplo: rizosfera e suas interações microbianas e organismos marinhos), visando novos agentes quimioterapêuticos. Neste trabalho, plântulas de Senna spectabilis foram cultivadas em hidroponia, com coleta da microflora da rizosfera realizada em três tempos diferentes de desenvolvimento do vegetal. No total, foi possível o isolamento de 51 bactérias e 129 fungos e, após identificação por filogenia (16S rRNA), encontrou-se, como principais gêneros: Shigella, Pseudomonas, Stenotrophomonas, Bacillus, Burkholderia, Pseudoxanthomonas, Arthrobacter, Achromobacter e Rhizobiu. Foram escolhidas três bactérias, codificadas como CSP-50a, CSP-52b e CSP-53b, para o estudo cinético bacteriano, visando à relação do crescimento com a produção metabólica. A análise mostrou que as bactérias atingiram a fase estacionária em 40 horas, período em que há produção de metabólitos secundários. Para a caracterização dos metabólitos, as três linhagens foram inoculadas em meio líquido Nutriente à 25 °C, sob agitação e, ao atingir a fase de interesse, foi realizada partição líquido-líquido com acetato de etila. Os extratos foram analisados por espectrômetria de massas visando a detecção e caracterização dos metabólitos majoritários. Foi possível detectar 08 compostos e identificar 02. Dentro desse o ácido metropheno e, uma uma série isomérica de amidas e formamidas foram evidenciadas. Adicionalmente, a presença da série foi também confirmada através de uso de uma metodologia de desreplicação preliminar utilizando RMN. / Nowadays, advanced technologies are developed for the discovery of unexplored natural sources (e.g. rhizosphere microbial interaction and marine organisms), targeting new chemotherapeutic agents. In this work, Senna spectabilis’s seedlings were cultivated in hydroponic environment, and its rhizosphere’s microflora collected at three different stages of the plant’s development. It was possible to isolate 51 bacterias and 129 fungi and, after identification by phylogenetic (16S rRNA), was determined the main genders, such as Shigella, Pseudomonas, Stenotrophomonas, Bacillus, Burkholderia, Pseudoxanthomonas, Arthrobacter, Achromobacter and Rhizobiu. We chose three of bacterias, coded as CSP-50a, CSP-52b and CSP- 53b, for kinetic’s studies, aiming the comparison between the bacteria growth and the production of metabolites. This analysis showed that they reached the stationary phase at an average of 40 hours, when the production of secondary metabolites started. To characterize those metabolites, the three strains were grown on liquid nutrient medium at 25°C under agitation to achieve the phase of interest, followed by liquid-liquid partition with ethyl acetate. Analysis by mass spectrometry was performed aiming the detection and characterization of the major metabolites. It was possible to detect 08 compounds and identify 02. Metrophene acid, as well as an isomeric formamide series were detected. Additionally the formamides were also confirmed by the use of a preliminary methodology using NMR dereplication tool.

Orientador: Ian Castro-Gamboa / Banca: Cíntia Duarte de Freitas Milagre / Banca: Flávia Talarico Saia / Resumo: O descobrimento de novas moléculas bioativas tem sido o grande al vo ao decorrer dos anos da química dos produtos naturais, particularmente, micro - organismos tem se evidenciado como uma importante fonte do descobrimento de novos fármacos. Uma ampla gama de compostos provenientes de organismos microbianos são relatados na literatura, porém, recentes pesquisas demonstram que tais micro - organismos podem sofrer indução por determinados agentes externos, químicos ou físicos, através de mecanismos de defesa ou até mesmo o mutualismo existente em determinado meio, produzindo nov as estruturas químicas, que até então, tinham sua rota b iosintética silenciada devido a metodologias padrões de cultivo isolado. Através de utilização de culturas mistas de bactérias, o presente trabalho proporciona o conhecimento da relação existente entr e Pseudoxanthomonas indica e Shigella sp., ambas provenientes da rizosfera de Senna spectabilis . Para isso, as bactérias foram cultivadas em meio de cultivo líquido czapek broth, sendo realizado o estudo do crescimento das bactérias e produção de metabolit os frente ao tempo, tendo em vista uma maximização de resultados e maior indução de compostos químicos. A utilização de ferramentas analíticas de análise rápida e eficiente como a cromatografia líquida de alta eficiência ( HPLC ) associada a espectrometria de massas de alta resolução do ( HRMS ) propiciaram a obtenção do perfil cromatográfico dos micro - organismos estudados em cultura mista e simples, sendo possível observar a existência de compostos químicos produzidos apenas em co - c ultura, evidenciado o potencial existente da abordagem utilizada. / Abstract: The discovery of new bioactive molecules has been the big target to over the ye ars the chemistry of natural products, particularly micro - organisms has been shown to be an important source of discovery of new drugs. A wide range of compounds from microbial organisms are reported in the literature, however, recent research shows that t hese micro - organisms can undergo induction by certain external, chemical or physical agents, through defense mechanisms or even the existing m utualism on a particular medium, producing new chemical structures, which until then had silenced their biosynthet ic route due to methodologies patterns of isolated farming. Through use of mixed cultures of bacteria, this study provides knowledge of the relationship between Pseudoxanthomonas indica and Shigella sp ., Both from the rhizosphere of Senna spectabilis . For this, bacteria were grown in liquid Czapek broth cultivation being conducted the study of the growth of bacteria and production of metabolites against time, with a view to maximizing results and greater induction of chemical compounds. The use of analytics quickly and efficiently analyzes such as high - performance liquid chromatograp hy tools (HPLC) associated with high resolution mass spectrometry (HRMS) enabled the obtaining of the chromatographic profile of microorganisms studied in mixed and single cultur e, and you can to observe the existence of chemical compounds produced only in co - culture demonstrated the potential of the approach used. / Mestre

Orientador: Ian Castro-Gamboa / Banca: Angela Regina Araujo / Banca: Flavia Talarico Saia / Resumo: Atualmente, avançadas tecnologias têm sido desenvolvidas para a exploração de fontes naturais pouco exploradas (exemplo: rizosfera e suas interações microbianas e organismos marinhos), visando novos agentes quimioterapêuticos. Neste trabalho, plântulas de Senna spectabilis foram cultivadas em hidroponia, com coleta da microflora da rizosfera realizada em três tempos diferentes de desenvolvimento do vegetal. No total, foi possível o isolamento de 51 bactérias e 129 fungos e, após identificação por filogenia (16S rRNA), encontrou-se, como principais gêneros: Shigella, Pseudomonas, Stenotrophomonas, Bacillus, Burkholderia, Pseudoxanthomonas, Arthrobacter, Achromobacter e Rhizobiu. Foram escolhidas três bactérias, codificadas como CSP-50a, CSP-52b e CSP-53b, para o estudo cinético bacteriano, visando à relação do crescimento com a produção metabólica. A análise mostrou que as bactérias atingiram a fase estacionária em 40 horas, período em que há produção de metabólitos secundários. Para a caracterização dos metabólitos, as três linhagens foram inoculadas em meio líquido Nutriente à 25 °C, sob agitação e, ao atingir a fase de interesse, foi realizada partição líquido-líquido com acetato de etila. Os extratos foram analisados por espectrômetria de massas visando a detecção e caracterização dos metabólitos majoritários. Foi possível detectar 08 compostos e identificar 02. Dentro desse o ácido metropheno e, uma uma série isomérica de amidas e formamidas foram evidenciadas. Adicionalmente, a presença da série foi também confirmada através de uso de uma metodologia de desreplicação preliminar utilizando RMN. / Abstract: Nowadays, advanced technologies are developed for the discovery of unexplored natural sources (e.g. rhizosphere microbial interaction and marine organisms), targeting new chemotherapeutic agents. In this work, Senna spectabilis's seedlings were cultivated in hydroponic environment, and its rhizosphere's microflora collected at three different stages of the plant's development. It was possible to isolate 51 bacterias and 129 fungi and, after identification by phylogenetic (16S rRNA), was determined the main genders, such as Shigella, Pseudomonas, Stenotrophomonas, Bacillus, Burkholderia, Pseudoxanthomonas, Arthrobacter, Achromobacter and Rhizobiu. We chose three of bacterias, coded as CSP-50a, CSP-52b and CSP- 53b, for kinetic's studies, aiming the comparison between the bacteria growth and the production of metabolites. This analysis showed that they reached the stationary phase at an average of 40 hours, when the production of secondary metabolites started. To characterize those metabolites, the three strains were grown on liquid nutrient medium at 25°C under agitation to achieve the phase of interest, followed by liquid-liquid partition with ethyl acetate. Analysis by mass spectrometry was performed aiming the detection and characterization of the major metabolites. It was possible to detect 08 compounds and identify 02. Metrophene acid, as well as an isomeric formamide series were detected. Additionally the formamides were also confirmed by the use of a preliminary methodology using NMR dereplication tool. / Mestre

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-09-08T19:29:03Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) tese definita com folha de aprovação CORREÇÃO BIBLIOTECA data imprimir gravar.pdf: 3647168 bytes, checksum: 1df93fa61cfc9c0e2d172eb9eb4b645e (MD5) / Made available in DSpace on 2016-09-08T19:29:03Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) tese definita com folha de aprovação CORREÇÃO BIBLIOTECA data imprimir gravar.pdf: 3647168 bytes, checksum: 1df93fa61cfc9c0e2d172eb9eb4b645e (MD5) Previous issue date: 2015-11-15 / A busca por novos metabólitos secundários de interesse biotecnológicos tem aumentoado nos últimos anos. O objetivo foi isolar micro-organismos endofíticos e da rizosfera, avaliar o potencial biotecnológico dos micro-organismos endofíticos e da rizosfera de Ipomoea pes-caprae. Os endófitos isolados foram inoculados em meio específico para bactérias, actinobactérias (ALA, Meio Completo, ISP2) e fungos (BDA e Agar Sabouraud) à temperatura de 30°C. Para o isolamento das actinobactérias da rizosfera foi utilizado 10 g da amostra do solo rizosférico e este foi misturado a 90 mL de NaCl a 0,9%(m/v) a pH (5,6). Estes micro-organismos foram cultivados em meios de cultura ISP2 e Czapeck Dox a 30 ºC por 7 dias. Foi realizada atividade antimicrobiana de todos os micro-oranismos isolados tanto endofítico como rizosféricos. Para a enzima L- asparaginase foi realizada análise qualitativa e cinética através de Fermentação Semi-Sólida com farinha de soja como substrato. Além da análise qualitativa da L-asparaginase foi verificada a presença de hidrolase (amilase, protease, celulase e lipase. A análise química do extrato metanólico do endófito Streptomyces sp, fungos e actinobactéria rizosférica Nocardia sp foi realizada utilizando a cromatografia de camada delgada (CCD). Das bactérias endofíticas foi avaliada sua capacidade de produção de Ácido Indol Acético. As frequências de endófitos isolados foram: fungos-folha 44.71% (55/123), fungos raízes 13% (16/123), bactérias-folhas 41.46% (51/123), bactérias raízes 1.62% (2/123), actinobactéria 0,81% (1/123). Da rizosfera foram isolados 81 actinobactérias. Na atividade antimicrobiana a maioria dos micro-organismos da rizosfera e endofíticos apresentou atividade antimicrobiana para bactérias Gram-positivas. No extrato dos micro-organismos endofíticos e rizosférico como no extrato da planta foram verificadas a presença de composto mono-sesquiterpenos. A produção de L-aspraginase foi verificada nos micro-organismos endofíticos e nas actinobactérias rizosférica. Na cinética de produção de L-asparaginase pelo endófito Streptomyces sp, verificou-se que o melhor dia de produção foi de 10° dia (0,0702 U/mL de L-asparaginase). Com relação as hidrolase foi verifacdo a presença de amilase e protease na maioria dos endofíticos. Das 53 bactérias endofíticas isoladas, 8 linhagens são produtoras de ácido indol acético. Por tanto, a prospecção dos micro-organismos rizosféricos e endofíticos isolados da planta I. pes-caprae (L.) R. Br. é uma promissora fonte de substâncias de interesse biotecnológico. / The search for new secondary metabolites of biotechnological interest has stepped up in recent years. The aim of present study was to isolate endophytic and rhizosphere micro-organisms to evaluate the secondary metabolites produced by micro-organisms associated with the leaves, roots and rhizosphere of Ipomoea pes-caprae. The endophytes isolated were inoculated in media specific to actinobacteria, bacteria (ALA, full medium, ISP2) and fungi (BDA and Agar Sabouraud) at a temperature of 30°C. The isolation of actinobacteria from the rhizosphere used 10 g of the rhizosphere soil sample mixed with 90 mL of NaCl at 0.9% (m/v) and pH 5.6. These micro-organisms were cultivated in ISP2 and Czapeck Dox culture media at 30 ºC for 7 days. Antimicrobial activity was analyzed. Qualitative analysis, 23 experimental planning and kinetic analysis of the enzymatic activity of L-asparaginase was carried out using semi-solid fermentation with soya flour as a substrate. Chemical analysis of the methanolic extract of the endophyte Streptomyces sp, fungi and the rhizosphere actinobacteria Nocardia sp was conducted using thin layer chromatography (TLC). The capacity of the endophytic bacteria to produce indole acetic acid was measured. The frequencies for isolated endophytes were: fungi-leaves 44.71% (55/123), fungi-roots 13% (16/123), bacteria-leaves 41.46% (51/123), bacteria-roots 1.62% (2/123), and actinobacteria 0.81% (1/123). Eighty-one actinobacteria were isolated from the rhizosphere. Most of the rhizosphere and endophytic micro-organisms exhibited antimicrobial properties against Gram-positive bacteria. Mono-sesquiterpene compounds were found in the endophytic and rhizospheric micro-organisms and in the plant extract. Production of L-asparaginase was found in endophytic micro-organisms and in actinobacteria from the rhizosphere. 23 experimental planning of the production of the L-asparaginase enzyme by the Streptomyces sp endophyte suggests that the lower the quantity of micro-organism inoculate, the concentration of L- asparagine and temperature, the better the production of the L-asparaginase enzyme. The kinetics of L-asparaginase production by the Streptomyces sp endophyte showed that the best day for production was the 10th (0.0702 U/mL of L-asparaginase). Of the 53 endophytic bacteria isolated, eight strains produced indole acetic acid. The prospection of rhizosphere and endophytic micro-organisms isolated from I. pes-caprae (L.) R. Br. is thus a promising source of substances of biotechnological interest.

About 150 rhizobacteria and 49 rhizosphere fungi were isolated from the rhizosphere of grasses and sedges at Nylsvley Nature Reserve, Limpopo Province, South Africa. The rhizobacterial isolated were mostly Gram negative (72%) and rod shaped (73%). The dominant fungal genera were Trichoderma, Aspergillus, Pencillium, Neosartorya and Fusarium. The antagonistic activity of the above isolates were determined in a dual culture assay against a range of plant pathogens namely Colletotrichum gloeosporioides, Pythium irregulare, Penicillium digitatum, Fusarium solani and Geotrichum candidum. All rhizosphere fungal isolates showed positive antagonism against G. candidum (100%) and F. solani (100%). The rhizobacterial isolates showed positive antagonism against G. candidum (71%) and C. gloeosporioides (76%). The growth promotion and biocontrol activity of the rhizosphere isolates that showed broad-spectrum antagonistic activity against the fore mentioned pathogens were further evaluated on Canadian peat substrate under greenhouse condition. Although most of the rhizosphere isolates resulted in improved fresh leaf weight in comparison with the non-inoculated control in final growth promotion experiments, no statistical difference could be found in increasing leaf weight by one of the tested isolates. Some isolates and BactolifeTM prevented root infection by Pythium. However, only isolate 68B showed significant prevention of root infection compared to the Pythium inoculated control. The selected rhizobacteria, fungal and commercial biocontrol products that showed the most effective growth promotion and biocontrol activities were further evaluated in a re-circulating hydroponic system. Overall, isolate BSB (Bacillus subtilis) consistently enhanced the fresh leaf and root weight by 29.82 and 24.31% compared to the untreated control. Treatments with rhizobacteria isolate 91B and 43B significantly increased fresh leaf weight and suppressed Pythium root infection of lettuce. Isolate 91B and 121B significantly decreased the incidence of Pythium after the 1st and 2nd week of inoculation respectively. The combination of rhizobacteria BSB and 43B showed a synergistic effect as reflected in increased fresh leaf weight and total biomass per plant whilst suppressing root rot caused by Pythium group-F. Copyright 2003, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Begashaw, L 2003, Utilisation of rhizosphere microflora in the biocontrol of root rot and growth enhancement of lettuce under hydroponic systems, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-05092005-103113 / > E642/ag</gm> / Dissertation (MSc (Agric))--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted

Magister Scientiae (Biodiversity and Conservation Biology) - MSc (Biodiv and Cons Biol) / The Bokkeveld Plateau, a region hosting high plant endemism, is home to two arid mountain centre renosterveld types. One, Nieuwoudtville Shale Renosterveld, has partially been transformed into croplands and pastures, with about 40 % remaining as non-contiguous fragments on privately owned land, and is used as natural rangelands for sheep grazing. The vegetation, soil chemical parameters, and rhizosphere soil microbial ecology of a dominant plant, Eriocephalus purpureus, were assessed. A combination of field sampling and recording, laboratory analyses of soil samples, and interviews were used to glean data. Data were statistically analysed using multivariate techniques. Overall plant species richness did not differ among the study sites, though plant species richness and cover of the different plant growth form categories varied among the sites. Soil chemical parameters varied among sites. Soil chemical and rhizosphere soil microbial parameters co-varied, and showed different profiles among the study sites. High cover of E. purpureus was associated with high microbial enzyme activity, while high cover of (other, non-dominant) non-succulent shrubs was associated with high bacterial functional diversity. Cover of geophytes, Asparagus capensis and perennial grass was associated with high microbial biomass. The findings indicate that E. purpureus-dominated Niewoudtville Shale Renosterveld is heterogeneous not only in terms of vegetation, but also in terms of soil chemical and microbial parameters. The results support the conservation of all fragments of remaining renosterveld, as they may serve as valuable resources of not only plant genetic material but also of soil microbial communities.

The objective of this study was to investigate the spatial and temporal trends of a phytoremediation system comprised of poplar trees designed to control groundwater flow and remove primarily polycyclic aromatic hydrocarbons (PAHs). Several lab and field studies have demonstrated the success of poplar trees in effectively decreasing concentrations of volatile hydrocarbons, but few have demonstrated effects on PAH concentrations. Thus, the focus of this report will be the response of the poplar trees in relation to hydrophobic, nonvolatile polycyclic aromatic hydrocarbons (acenapthene, acenapthylene, anthracene, chrysene, fluoranthene, naphthalene, phenanthrene, and pyrene) in a shallow, surficial aquifer. This field study was conducted on a 1.7-acre site in Oneida, Tennessee contaminated with creosote that was once used for railroad cross-tie treatment. Spatial analysis was used to divide the site into areas based on contaminant levels and a layer of coal that served as a layer of low permeability at an approximate depth of 2 feet. The semi-impermeable coal layer does have an adverse impact on tree growth, while the contamination does not appear to adversely affect tree growth. The rate of growth is also impacted by the age of the tree at planting where younger trees grow faster than the older trees. A steady decrease in PAH concentrations has occurred at the multi-level samplers surrounded by a root zone that has penetrated the contamination. PAH compounds present at relatively high concentrations in the soil and groundwater do not appear to affect tree growth to a greater or lesser extent than lower PAH concentrations. While further research is required to affirm the positive effects of poplar trees at this site, the tree stand has responded well to the high PAH levels. / Master of Science

No description available.