No description available.

No description available.

Legionella can cause human disease which can be fatal. Routine monitoring for Legionella in water systems is not recommended by UK authorities. Evidence of the efficacy of control modalities against Legionella in these water systems is, therefore, not available. Although studies have been conducted with copper and silver ionization on its efficacy against Legionella and on its value in reducing hospital-acquired legionellosis, little evidence of its efficacy is available from routine monitoring data. This study demonstrates the efficacy of copper and silver ionization against Legionella in water systems of 10 hospitals from data obtained from routine monitoring for Legionella, copper and silver. The inefficiencies of maintaining temperatures above 50ºC at hot outlets and below 20ºC at cold outlets, as recommended by UK authorities for controlling Legionella in water systems, is also demonstrated from the data obtained from routine monitoring for Legionella and temperatures. The futility of maintaining hot temperatures above 50ºC and then to reduce them to temperatures that do not present a risk of scalding is also demonstrated from the data obtained. This efficacy of copper and silver ionization and inefficiency of maintaining temperatures at 50ºC against Legionella was demonstrated as well in novel model rigs, built to simulate a typical water system of a small hospital, by data obtained from Legionella, copper, and silver analysis, and temperature recordings. The differences in biofilm formation and Legionella growth on the surfaces of copper, polyethylene, and synthetic rubber, which are commonly used plumbing materials, were also examined in the model rigs as well as with a Robbins device. These studies indicated that copper is not as biocidal as previously reported in other studies, and gave similar results to polyethylene, which previously been shown to promote biofilm development. Synthetic rubber, however, showed to promote biofilm production and should not be used as a plumbing material.

Around half of oral bacteria have yet to be cultured, and their role in disease is therefore unknown. It is hypothesised that bacteria in biofilms have become dependent on growing in multi-species communities. TM7 phylum has no cultured representatives and some oral TM7 phylotypes have been associated with oral diseases such as periodontitis. The aims of this study were therefore to evaluate the ability of two model culture systems: Cooked Meat Medium and the Calgary Biofilm Device (CBD), to support the growth of mixed oral bacterial communities including uncultured bacteria, and to attempt to culture representatives of the TM7 division. The Cooked Meat Medium was used to establish a mixed bacterial community from 3 endodontic samples and their composition was analysed by Sanger sequencing and 454 pyrosequencing. A diverse bacterial community closely related to the original endodontic samples was maintained up to 480 days and included some uncultured bacteria present in the original samples. A mixed oral biofilm was established on the CBD from saliva. The effect of the presence of mucin and glucose in the growth media on community composition was evaluated, but no significant differences were seen. The effect of using propidium monoazide to remove extracellular DNA was assessed and was found to significantly affect the perceived composition of the biofilms. Uncultured taxa detected in culture included representatives of deep branches of Bacteroidetes and Clostridiales, and TM7 and SR1 phyla. TM7 members were detected in both models with specific PCR primers, but their proportion never exceeded 1 %. In an attempt to isolate TM7 division representatives a saliva microcosm was grown on agar. TM7 representatives were detected by colony hybridization and specific PCR and subcultured, producing enrichment. Two simple co-cultures of TM7 HOT352/HOT353 with Slackia exigua or Atopobium parvulum were obtained, but were not maintained.

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Cyanobacteria or blue-green algae are important resources. In some parts of the world, cyanobacteria are used as a staple food and their ability to fix nitrogen has been explored toincrease the productivity of many crops and transform a barren soil into a fertile one. An interesting property of cyanobacteria is their ability to absorb nitrogen and inorganic phosphorous, so they have been seen in water purification systems. Most interestingly cyanobacteria produce O2 and H2 by the combination of photosynthesis and nitrogen fixing ability; they could potentially become a producer of hydrogen fuel. This project investigates the characterizations of cyanobacteria cultivation in a tubular baffled photo bioreactor(TBPBR). Many benchmarking experiments were conducted in light boxes in order to understand the reaction kinetics and to examine the effects of the ratio of aeration surface over culture volume, light intensity, light quality, light cycle, mixing, initial cell density and temperature on the growth of Gloeothece membranacea and Oscillatoria amoena. Based on the benchmarking results, a tubular baffled photo bioreactor (TBPBR) was designed, constructed and commissioned. Further experiments were conducted using Gloeothece membranacea in order to characterize the continuous cultivation of in this novel photobioreactor; examine the effects of the light saturation and the period of light availability V on cell growth and determine the critical cell density for optimal growth. The kinetics information was extracted and compared with that of the benchmarking trials. The light saturation level for Gloeothece membranacea in the TBPBR was 80 μmole m-2 sec-1, and the minimum light exposure without affecting the growth was 6 hours, same as that in the light boxes. Also, much higher critical cell density (CCD)g of Gloeothece membranacea could be accommodated in the TBPBR than that in the light boxes. Furthermore, the optimum specific growth rate of Gloeothece membranacea was obtained at aeration flow rate of 0.08 vvm and Vol CO2/ Vol air = 6%.

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No description available.

No description available.

Salmonella Typhimurium is a major cause of morbidity and mortality in humans. It is also a commonly used model organism for intracellular Gram negative pathogens, a group of bacteria that is becoming increasingly resistant to available antibiotics. Systemic Salmonella infection involves proliferation in the small intestine followed by infection of epithelial and later macrophage host cells. In order to advance the understanding of the r^ole of metabolism in virulence, a genome-scale metabolic model of S. Typhimurium was constructed, based on genomic and biochemical data obtained from public databases. A method for modelling metabolic interactions between cells was developed and applied to models of S. Typhimurium and the probiotic Lactobacillus plan-tarum, in order to simulate the intestinal stage of infection. The analysis indicated that interactions, involving the transfer of glycolate from L. plantarum to S. Typhimurium, that favour growth of S. Typhimurium, are possible, by unlikely to occur in vivo. Data from Phenotype Microarray (PM), as well as DNA microarray data obtained during infection of cultured macrophage cells, was integrated with the S. Typhimurium model. The PM data was largely in agreement with model results for growth on carbon and nitrogen sources, and indicated moderate agreement for sulphur and phosphorus sources. A model-based method for analysis of nutrient availability during growth inside host cells, based on PM and DNA microarray data, was developed. This environment is poorly characterised and direct experimental methods for obtaining this information are not available. The analysis indicated a nutritionally complex host environment, dominated by glycerol 3-phosphate and certain nucleosides and amino acids. Owing to the complexity of the host environment, a method for identication of a sub-network of the model, required for viability on all growth supporting carbon sources was developed. The impact of sequentially removing combinations of reactions in the sub-network from the genome-scale model was evaluated. This analysis suggested approximately 60 reactions that in various combinations could be of relevance for designing antimicrobial intervention strategies, including antimicrobial agents and live attenuated vaccines.