Thesis (M. Tech. Environmental health) -- Central University of technology, Free State, 2011 / The threat to the world food supply and the concern for public health as a result of food-borne diseases has been established as a constant global problem. The safety of food, in particular, is of significance to consumers and producers alike. Regarding the diseases related to food-borne pathogens, the disease syndromes affecting the entire human body has become inestimable. The focus of the study was to establish the effect of sanitisers, detergents and household storage temperatures on the growth profiles and toxicity of typical food related organisms. The endotoxin, LPS of these Gram-negative organisms in communal growth as compared to pure culture was the focus of the investigation. Pure and communal samples were grown in the presence of the extrinsic stresses including storage temperature. The change in toxicity was measured using the Limulus amoebocyte lysate test and the possible change in the immune response was determined using the porcine-IL-6 test. The first obvious finding was that the overall sensitivity of organisms was similar for the same sanitiser and the same detergent. The sensitivity of the community varied slightly but in principle followed the same pattern as the individual organisms. The LD50 for all growth samples were as follows: 32 X 104 PPM for sanitiser 1 and sanitiser 2, and 16X 104 PPM for detergent 1 and detergent 2. Growth in community was found not to be the arithmetic sum of the individual growth patterns. The detergents had a marked effect on the growth of all samples throughout the growth cycle. The sub-optimum household storage temperatures inhibited the growth throughout the cycle but growth did not cease entirely. This finding may have revealed that the acceptable refrigeration temperatures still allows for pathogen growth and thus for biofilm formation. Furthermore, the response of the community to the extrinsic stresses appears to be entirely different to the pure culture and therefore needs further exploration to address the problem. Regarding the quantification by LAL, it was found that the enumeration of the food-borne pathogens isolated from households might not be indicative of acclimatisation obtained over short periods of time and the causal stress turning these organisms into more or less toxic pathogens. The sanitisers and detergents induced competition in colonial fashion and the growth varied between feast and famine. The extrinsic stresses had a more observable effect on the older biofilm as this was shown by a decrease in toxicity. The toxicity as quantified by porcine-IL-6 yielded a mixture of stimulation levels for the cytokine. The toxicity change indicated by the test showed a variation between lowering and noticeable elevation for pure cultures. A marked elevation in toxicity was detected in community at storage temperature 4°C. The study would suggest that porcine IL-6 is not an accurate biomarker for pyrogenicity since its sensitivity is questionable and its inability to indicate toxicity if there is a possible change in the LPS structure. It should be said that further elucidation is needed to support this finding. Having said all that, it is no surprise that the validation for the two tests favours the LAL procedure. The large room for pre-test stimulation in pigs’ blood also tends to cast a shadow on the IL-6 findings. The findings of the study contribute to the body of knowledge covering the effects and quantitative analysis of toxins in food. This should add to safety assurance by sensitizing the industry regarding the most suitable analytical methodologies to apply.

Made available in DSpace on 2014-06-11T19:22:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-12-04Bitstream added on 2014-06-13T19:27:10Z : No. of bitstreams: 1 silva_ipf_me_botfca.pdf: 811263 bytes, checksum: f5d3077013320ac555e0dc1689b1cc81 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O glufosinate é um herbicida derivado do fosfinotricina, uma toxina microbiana natural isolada a partir de duas espécies de fungos do gênero Streptomyces. O mecanismo de ação é a inibição direta da enzima glutamina sintetase, que resulta no aumento da concentração de amônio, sendo tóxico para as células. A pesquisa teve como objetivo avaliar a velocidade de absorção do glufosinate e seus efeitos em plantas daninhas e na cultura do algodão. O experimento foi conduzido em casa-de-vegetação com o cultivar de algodão FiberMax 910 e as plantas daninhas Brachiaria decumbens e Ipomoea grandifolia plantadas em vasos. O experimento foi instalado com duas formulações do herbicida, glufosinate de amônio (2,0 L p.c. ha-1) e glufosinate de potássio (2,0 L ha-1), cinco períodos sem a ocorrência de chuvas (1; 3; 6; 24 e 48 horas após aplicação) e uma testemunha sem aplicação com quatro repetições por tratamento. As plantas para as análises laboratoriais foram coletadas com dois dias após aplicação, quando começaram a aparecer os primeiros sintomas de intoxicação visual. As variáveis analisadas foram teor de amônia, glutamato, glutamina e glufosinate; sintomas de intoxicação visual e taxa de transporte de elétrons (ETR). Foi observado... / Glufosinate is derived of phosphinothricin, a natural microbial toxin isolated from two species of the Streptomyces fungus. The mechanism of action is through direct inhibition of the glutamine synthetase enzyme, which results in the increase of ammonium concentration, becoming toxic to the cells. The objective of this study was to evaluate the rate of absorption of glufosinate and its effects on weeds and cotton culture. The experiment was conducted in a green house, the cultivar of cotton FiberMax 910, Brachiaria decumbens and Ipomoea grandifolia planted in 5 liter pots. The experiment was conducted with two formulations of the herbicide, glufosinate ammonium (2.0 pc L ha-1) and glufosinate potassium (2.0 L ha-1), five periods without rainfall (1, 3, 6, 24 and 48 hours after application) and an untreated control with all treatments were replicated four times. The plants for laboratory analysis were collected within 2 days after application, when the first visual symptoms of intoxication began to appear. The analyzed variables were the ammonia content, the content of compounds that belongs to the glufosinate metabolic route (glutamate and glutamine), glufosinate content, visual symptoms of intoxication and electron transport rate (ETR). It was observed that the absorption of glufosinate occurs within 48 hours of application for both formulations and evaluated species. The amount of ammonia in the commercial formulation did not interfere with ammonia levels observed in intoxicated plants. The highest levels of ammonia for cotton occurred at 5 hours without rain, and for B. decumbens and I. grandifolia with 6 hours without rain. We have observed a significant reduction of glutamate and glutamine in plants treated with the two formulations of glufosinate, with the lowest levels found in cotton and B. decumbens carried out in... (Complete abstract click electronic access below)

Orientador: Caio Antonio Carbonari / Coorientador: Edivaldo Domingues Velini / Banca: Fernando Tadeu de Carvalho / Banca: Ana Catarina Cataneo / Resumo: O glufosinate é um herbicida derivado do fosfinotricina, uma toxina microbiana natural isolada a partir de duas espécies de fungos do gênero Streptomyces. O mecanismo de ação é a inibição direta da enzima glutamina sintetase, que resulta no aumento da concentração de amônio, sendo tóxico para as células. A pesquisa teve como objetivo avaliar a velocidade de absorção do glufosinate e seus efeitos em plantas daninhas e na cultura do algodão. O experimento foi conduzido em casa-de-vegetação com o cultivar de algodão FiberMax 910 e as plantas daninhas Brachiaria decumbens e Ipomoea grandifolia plantadas em vasos. O experimento foi instalado com duas formulações do herbicida, glufosinate de amônio (2,0 L p.c. ha-1) e glufosinate de potássio (2,0 L ha-1), cinco períodos sem a ocorrência de chuvas (1; 3; 6; 24 e 48 horas após aplicação) e uma testemunha sem aplicação com quatro repetições por tratamento. As plantas para as análises laboratoriais foram coletadas com dois dias após aplicação, quando começaram a aparecer os primeiros sintomas de intoxicação visual. As variáveis analisadas foram teor de amônia, glutamato, glutamina e glufosinate; sintomas de intoxicação visual e taxa de transporte de elétrons (ETR). Foi observado... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Glufosinate is derived of phosphinothricin, a natural microbial toxin isolated from two species of the Streptomyces fungus. The mechanism of action is through direct inhibition of the glutamine synthetase enzyme, which results in the increase of ammonium concentration, becoming toxic to the cells. The objective of this study was to evaluate the rate of absorption of glufosinate and its effects on weeds and cotton culture. The experiment was conducted in a green house, the cultivar of cotton FiberMax 910, Brachiaria decumbens and Ipomoea grandifolia planted in 5 liter pots. The experiment was conducted with two formulations of the herbicide, glufosinate ammonium (2.0 pc L ha-1) and glufosinate potassium (2.0 L ha-1), five periods without rainfall (1, 3, 6, 24 and 48 hours after application) and an untreated control with all treatments were replicated four times. The plants for laboratory analysis were collected within 2 days after application, when the first visual symptoms of intoxication began to appear. The analyzed variables were the ammonia content, the content of compounds that belongs to the glufosinate metabolic route (glutamate and glutamine), glufosinate content, visual symptoms of intoxication and electron transport rate (ETR). It was observed that the absorption of glufosinate occurs within 48 hours of application for both formulations and evaluated species. The amount of ammonia in the commercial formulation did not interfere with ammonia levels observed in intoxicated plants. The highest levels of ammonia for cotton occurred at 5 hours without rain, and for B. decumbens and I. grandifolia with 6 hours without rain. We have observed a significant reduction of glutamate and glutamine in plants treated with the two formulations of glufosinate, with the lowest levels found in cotton and B. decumbens carried out in... (Complete abstract click electronic access below) / Mestre

Indiana University-Purdue University Indianapolis (IUPUI) / Pseudomonas aeruginosa is a gram negative opportunistic pathogen with the capacity to cause serious disease by forming biofilms, most notably in the lungs of cystic fibrosis (CF) patients. Biofilms are communities of microorganisms that adhere to a solid surface, undergo global regulatory changes, secrete exopolysaccharides, and are innately antibiotic resistant. Virulence modulation is an important tool utilized by P. aeruginosa to propagate infection and biofilm formation in the CF airway. Many different virulence modulatory pathways and proteins have been identified including the protein, MgtE. MgtE has recently been discovered and has been implicated in virulence modulation, as an isogeneic mutation of mgtE leads to increased cytotoxicity. To further elucidate the role of MgtE in P. aerugionsa infections, transcriptional and translational regulation of this protein following antibiotic treatment has been explored. I have demonstrated that mgtE is transcriptionally upregulated following antibiotic treatment of most of the twelve antibiotics tested utilizing RT-PCR and QRT-PCR. A novel model system was employed, which utilizes cystic fibrosis bronchial epithelial (CFBE) cells homozygous for the ΔF508 mutation for these studies. This model system allows P. aeruginosa biofilms to form on CFBE cells modeling the P. aeruginosa in the CF airway. Translational effects of antibiotic treatment on MgtE have been attempted via Western blotting and cytotoxicity assays. Furthermore, to explore the possibility that mgtE is interacting with a known regulatory pathway, a transposon-mutant library was utilized and the regulatory proteins, AlgR and NarX, among others have been identified as possibly interacting with MgtE. Lastly, an MgtE homologue from Staphylococcus aureus was utilized to further demonstrate the virulence modulatory effects of MgtE by demonstrating the expression of the homologue results in decreased cytotoxicity, exactly like expression of the native P. aeruginosa MgtE. This research explores a newly discovered protein that impacts cytotoxicity and biofilm formation and provides valuable information about P. aeruginosa virulence.

Indiana University-Purdue University Indianapolis (IUPUI) / In this research, Environmental Fluid Dynamic Code (EFDC) and Adaptive- Networkbased Fuzzy Inference System Models (ANFIS) were developed and implemented to determine the spatial-temporal distribution of cyanobacterial metabolites: 2-MIB and geosmin, in Eagle Creek Reservoir, IN. The research is based on the current need for understanding algae dynamics and developing prediction methods for algal taste and odor release events. In this research the methodology for prediction of 2-MIB and geosmin production was explored. The approach incorporated a combination of numerical and heuristic modeling to show its capabilities in prediction of cyanobacteria metabolites. The reservoir’s variable data measured at monitoring stations and consisting of chemical/physical and biological parameters with the addition of calculated mixing conditions within the reservoir were used to train and validate the models. The Adaptive – Network based Fuzzy Inference System performed satisfactorily in predicting the metabolites, in spite of multiple model constraints. The predictions followed the generally observed trends of algal metabolites during the three seasons over three years (2008-2010). The randomly selected data pairs for geosmin for validation achieved coefficient of determination of 0.78, while 2-MIB validation was not accepted due to large differences between two observations and their model prediction. Although, these ANFIS results were accepted, the further application of the ANFIS model coupled with the numerical models to predict spatio-temporal distribution of metabolites showed serious limitations, due to numerical model calibration errors. The EFDC-ANFIS model over-predicted Pseudanabaena spp. biovolumes for selected stations. The predicted value was 18,386,540 mm3/m3, while observed values were 942,478 mm3/m3. The model simulating Planktothrix agardhii gave negative biovolumes, which were assumed to represent zero values observed at the station. The taste and odor metabolite, geosmin, was under-predicted as the predicted v concentration was 3.43 ng/L in comparison to observed value of 11.35 ng/l. The 2-MIB model did not validate during EFDC to ANFIS model evaluation. The proposed approach and developed methodology could be used for future applications if the limitations are appropriately addressed.