Neste trabalho foi empregada uma metodologia rápida e eficiente para a identificação de metabólitos fitotóxicos produzidos por microrganismos. O isolamento do composto bioativo foi guiado através de bioensaio com Lemna minor. A espectrometria de massas, em especial o LC-MS, foi utilizada para acelerar o processo de identificação do composto ativo. As bactérias estudadas eram simbióticas do fungo fitopatogênico Sclerotium rolfsii. Seus respectivos extratos orgânicos obtidos de culturas em meio BD (batata dextrose) foram submetidos ao ensaio de fitotoxicidade com Lemna minor. Entre cinco bactérias foi selecionada a bactéria Burkholderia sp, a qual apresentou maior atividade no ensaio de fitotoxicidade. O fracionamento por cromatografia em coluna de sílica propiciou a identificação de uma fração ativa. A fitotoxina foi caracterizada como sendo um macropentólido de 20 membros. O composto pertence à classe dos polihidroxibutiratos (PHBs). Sua estrutura foi determinada por RMN 1H, RMN 13C, HMQC, HMBC, IV, ESI-MS/MS e também por comparação com dados da literatura. Esse composto nunca foi isolado de fontes naturais. Foi descrito na literatura uma rota sintética para sua obtenção, porém esta é a primeira vez que sua atividade fitotóxica é relatada. Este trabalho mostra uma nova perspectiva para o emprego de PHBs de baixo peso molecular e apresenta uma proposta de estrutura de composto fitotóxico que pode servir de modelo para a síntese de novos herbicidas. / In this work a quick and efficient methodology was employed for the identification of phytotoxic metabolites produced by microorganisms. The isolation of the bioactive compound was guided by Lemna minor bioassay. Mass spectrometry, especially LC-MS, was used to accelerate the process of identification of the phytotoxin. All bacteria were symbiotic to the phytopatogenic fungi Sclerotium rolfsii.. The bacterium Burkholderia sp was selected among the five bacteria analyzed, due to its greater phytotoxic activity in the bioassay. The phytotoxin was characterized as a 20 member macropentolide. This compound belongs to the polyhidroxybutirates (PHBs) chemical class. Its structure was determined by NMR1H, NMR 13C, HMQC, HMBC, IV, ESI-MS/MS and HRMS. It has never been isolated from natural sources before. Although a synthetic route has been proposed in the literature this is the first time that its phytotoxic activity is reported. This work leads to a new perspective for the application of low molecular weight PHBs and propose a phytotoxic structure that can be used as a model for the synthesis of new herbicide class.

Halten näringsämnen i livsmedel varierar bland annat med tillagningsmetod, lagringstid och lagringsförhållanden, som exponering för ljus och syre. Oklarheter finns för mikrovågors inverkan på näringsämnen och framförallt på vitamin B12. Eftersom många äldre drabbas av brist på vitamin B12, är detta av intresse eftersom många hemmaboende äldre människor får hemleverans av färdiga matportioner som är avsedda att värmas, ofta i mikrovågsugn. Syftet med studien var att kunna ge en indikation på om uppvärmning genom mikrovågor påverkar halten vitamin B12 i färdiga kylda måltider. Detta gjordes genom litteratursammanställning om vitamin B12 och mikrovågar samt genom bioassay med Lactobacillus delbrueckii. Vitamin B12 i ouppvärmd lax, lax värmd i mikrovågsugn samt lax värmd i konventionell ugn analyserades. Tillväxten av bakterier uppskattades genom mätning av turbiditet. Högst vitamin B12-halt sågs i mikrovågsvärmd lax, därefter ouppvärmd lax och ugnsvärmd lax. Statistiskt signifikanta skillnader sågs för analyserade vitamin B12-halter mellan ouppvärmt- och ugnsvärmt prov respektive mellan mikrovågsvärmt- och ugnsvärmt prov. De varierande vitaminhalterna kan bero på metodfel, otillräcklig vitaminextraktion eller att bakterierna inte konsumerat allt tillgängligt vitamin vid turbiditetsmätning. Slutsatsen av studien är att halten vitamin B12 i livsmedel inte verkar påverkas negativt av mikrovågor, däremot finns tendenser att halten minskar beroende av temperatur och tillagningstid.

M. Tech. / Diarrhoeal disease is an important public health problem worldwide as it is responsible for approximately 4 billion cases of diarrhoea per annum, of which 1.8 billion cases result in death. In most cases the causative agents are bacterial entero-pathogens such as Escherichia coli (E. coli), Salmonella, Shigella and Vibrio species. They enter the human body after consumption of contaminated water and food via the faecal-oral route of transmission. These pathogens are therefore identified from faecal matter with microbiological methods such as culture based techniques. There are however certain factors which negatively impact on the diagnosis. Recent literature has shown that bacterial pathogens may not be detected when they enter into a viable but non-culturable state (VBNC) making it difficult to detect the bacterial pathogens with culture based methods. The aim of the study was to detect entero-pathogenic bacteria from stool specimens using optimised protocols and a novel collection technique called the Bio-wipe kit. In the past sterile containers were used to collect and transport faecal matter to the WHRU laboratory for analysis. The disadvantage of this collection technique was that individuals were hesitant to provide faecal matter in a transparent container due to their social and moral status. The Bio-wipe kit eliminated some of the problems encountered with the previous collection technique as it is used in the same way as toilet tissue. Factors such as storage time and temperature was investigated for the recovery of faecal matter from the Bio-wipes since it was used in rural villages where the stool samples can not be refrigerated and transported to the lab immediately after the diarrhoeal episode. It was shown that the bacterial DNA can be recovered from the Bio-wipes within 5-10 days after usage when stored at 30°C and within 14 days after usage when stored at ambient temperature. Comparison of two in-house DNA extraction methods with the commercially available QIAamp® DNA stool mini kit indicated that the Guanidium thiocyanate without alpha casein method (GuSCN non ά-casein) could efficiently recover bacterial DNA from faecal matter free from the presence of inhibitors. This methodology could successfully recover amplifiable bacterial DNA in 92% (181/197) of the clinical Bio-wipes collected from individuals in the rural areas of the Vhembe region of the Limpopo province of South Africa. Various multiplex PCR’s (m-PCR) were optimised for this study for the detection and classification of diarrhoeagenic E. coli types, Salmonella, Shigella and Vibrio species. These m-PCR’s were proven to be very sensitive at detecting diarrhoegenic E.coli, Salmonella, Shigella and Vibrio species bacteria from the Bio-wipes. The extracted bacterial DNA from Bio-wipes recovered from clinical samples was amplified with the single genus specific multiplex PCR and 92% (181/197) of the samples tested positive for the E. coli mdh housekeeping gene, 3% (7/197) tested positive for the sodB housekeeping gene for V. cholerae spp, 5% (10/197) tested positive for the IpaH and Ial virulence genes for Shigella spp. and entero-invasive E. coli (EIEC) whereas none of the samples tested positive for the Salmonella virulence gene (IpaB). These results were confirmed with species specific multiplex PCR for each pathogen. It was concluded from this study that the Bio-wipe kit could be used for the collection of diarrhoeal and non-diarrhoeal faecal matter. The bacterial DNA could effectively be isolated from the recovered faecal matter using the GuSCN non α-casein DNA extraction method. The genus specific m-PCR was able to amplify low levels of bacterial DNA isolated from the Bio-wipes and thus the causative agents for diarrhoeal disease can successfully be diagnosed with the genus specific m-PCR. The Bio-wipe kit can be implemented for routine analysis and during diarrhoeal outbreaks as it is a cost effective, easy to use collection kit. The bacterial pathogens can easily and rapidly be diagnosed using the optimised molecular techniques instead of classical culture-based techniques.

No description available.

The revegetation of sterile acid mine spoils is a costly and lengthy process due to the many factors (pH, toxic materials, low nutrients, poor soil structure, temperature, moisture, length of growing season, etc.) which impede the establishment of stable plant communities . A microbial bioassay t echnique applied to soil systems has been developed to allow a rapid (four weeks) and integrated (with respect to nutrients and toxicants) determination of the best amendments for stabilizing mine spoils by revegetation. Using mine spoil from the Blackbird Mine, Cobalt (near Salmon), Idaho, various comb illations of nitrogen, phosphorus, chelaors, trace elements, potassium, manure and sal t leaching were studied with the bioassay by observing microscopically and by measuring nitrogen fixation and accumulation, dehydrogenase activity, chlorophyll~ accumulation, and other chemical parameters. It was concluded that the limiting factors for microbial (algal) growth were, in order of importance, pH control, soil moisture, and phosphorus. Other treatments failed to show statistically significant better results over the control. The fate of phosphorus in the spoil and its effecton growth response kinetics is also speculatively discussed.

Although modern medicine made great steps toward curing most diseases considered deadliest, yet cancer remains one of the major public health problems. The first part of this thesis investigates a new source of selective compounds that are potential candidates against cancer. Fifteen Russian compounds were tested in order to establish their efficiency against two types of cancer: human breast SK-Br-3 and colorectal carcinoma HT-29. The bioassay results show that seven of the new synthetic Russian compounds can be considered new drug leads, based upon their low toxicity and efficacy in slowing the growth of human breast cancer and colon cancer cells. The goal of the second part of the thesis was to isolate pure compounds that inhibit the growth of cancer cells from the methylene chloride extract of Eucalyptus viminalis Labill. This plant was selected for investigations since a preliminary screening of plants from Russia indicated that had activity against cancer. The result of this work was the isolation of a pure compound which has been analyzed using different spectroscopic techniques such as MS, HPLC, 1H-NMR, DEPT, 13C-NMR. The extracted compound was â-amyrin formate, which was previously reported by Malhotra,[49] from Canarium strictum Gum in 1987. Also, the bioassay results indicated that â-amyrin formate might be considered a possible drug lead against colon cancer and can be recommended for further investigations. This is the first report of isolation of â-amyrin formate from Eucalyptus viminalis Labill and the first test of the activity of this compound against colon cancer.

Gold nanoparticles (AuNPs) with their unique sizes, shapes, and properties have generated much enthusiasm over the last two decades, and have been explored for many potential applications. The successful application of AuNPs depends critically on the ability to modify and functionalize their surface to provide stability, compatibility, and special chemical functionality. This dissertation is aimed at exploring the chemical synthesis and surface modification of AuNPs with the effort to (1) control the number of functional groups on the particle surface, and to (2) increase the colloidal stability at the physiological conditions. To control the functionality on the particle surface, a solid phase place exchange reaction strategy was developed to synthesize the 2 nm AuNPs with a single carboxylic acid group attached on the particle surface. Such monofunctional AuNPs can be treated and used as molecular nanobuilding blocks to form more complex nanomaterials with controllable structures. A "necklace"-like AuNP/polymer assembly was obtained by conjugating covalently the monofunctional AuNPs with polylysine template, and exhibited an enhanced optical limiting property due to strong electromagnetic interaction between the nanoparticles in close proximity. To improve the colloidal stability in the psychological condition, biocompatible polymers, polyacrylic acid (PAA), and polyethylene glycol (PEG) were used to surface modify the 30 nm citrate-stabilized AuNPs. These polymer-modified AuNPs are able to disperse individually in the high ionic strength solution, and offer as the promising optical probes for bioassay applications. The Prostate specific antigen (PSA) and target DNA can be detected in the low pM range by taking advantages of the large scattering cross section of AuNPs and the high sensitivity of dynamic light scattering (DLS) measurement. In addition to the large scattering cross section, AuNPs can absorb strongly the photon energy at the surface plasmon resonance wavelength and then transform efficiently to the heat energy. The efficient photon-thermal energy conversion property of AuNPs has been used to thermal ablate the Aβ peptide aggregates under laser irradiation toward Alzheimer's disease therapy.

The discharge of wastewaters containing ammonia has become a major environmental concern, especially in the Chesapeake Bay watershed. A tentative instream limit of 1-2 mglL for total ammonia has been proposed in Virginia to protect marine aquatic life. This limit was based upon the national chronic criterion for un-ionized ammonia (0.035 mg/L) which was calculated using both freshwater and saltwater toxicity data. Therefore, additional bioassays needed to be performed with marine organisms in order to refine this limit based solely on saltwater organisms. Acute bioassays were conducted with one marine fish, the sheepshead minnow (Cyprinodon variegatus), and two marine invertebrates, the mysid (Mysidopsis bahia), and grass shrimp (Palaemonetes pugio). The acute LC 50 and the no-observed-effect-concentration (NOEC) were determined for each organism and compared to data in the literature. The species mean acute values (SMA V) for the sheepshead minnow (13.5% difference) and the mysid (14.7% difference) compared well with the literature, while the grass shrimp was more tolerant (81.2% difference) to ammonia than expected. The SMA V were calculated based upon the LC 50 data and used to assess both the national acute and chronic criterion for ammonia. Seven day chronic bioassays were performed with the sheep shead minnow (Cyprinodon variegatus). The LC 50 and the NOEC for both mortality and growth were calculated. The acute-chronic ratio was determined to be 6.95 for the sheepshead minnow and 4.35 for the mysid. Based upon these data, the refined national criteria for unionized ammonia was determined to be 0.054 mg/L. The instream limit can be set based upon the water pH, temperature, and salinity. / Master of Science

No description available.

Periphytic algae biomass, periphyton taxonomic composition and water quality were monitored from October, 1978 through October, 1979 in three experimental ponds on the University of Central Florida campus, Orlando, Florida. Differences in the abundance and seasonal periodicity of phytoplankton in the ponds presumably arose from intrinsic differences in the nature of the pond sediments. Ceramic tile and pressboard wood artificial substrates were sampled at two-month intervals to provide estimates of periphyton biomass and productivity; there was no significant difference in algal biomass on wood and tile substrates. Algal productivity on continuous-immersion (cumulative) substrates which supported a large accumulation of periphyton was substantially lower than productivity on uncolonized substrates immersed during the same period. thus indicated the existence of a carrying capacity for the periphyton community. Turbidity, which was largely determined by phytoplankton abundance, was significantly higher in Pond 2 (7.50 FTU) than in Ponds 1 and 3 (2.60 and 2.53 FTU, respectively) and resulted in reduced light penetration and development of a heterotrophic periphyton community in Pond 2. The algal flora of Pond 2 was dominated by small conditions, whereas Ponds 1 and 3 possessed periphyton communities dominated by large, filamentous green algae indicative of "clean" water.