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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Siderophore production of fluorescent pseudomonads is sensitive to fluctuations in the levels of oxygen and carbon dioxide

Kim, Do Hoon, 1962- January 1989 (has links)
Four strains of the fluorescent pseudomonads were studied to determine the effect of controlled atmospheres on the growth and fluorescent siderophore production at pH 6.0 and 7.8. Bacterial strains were grown in Liquid King's Medium B for 48 hr in the presence of O2/CO2 combination percentages of 21.0/0.03, 18.3/3.0, 15.0/6.0, 12.0/9.0, and 9.0/12.0. The bacterial biomass was determined after centrifugation and the siderophores were isolated, partially purified, and quantified spectrophotometrically. Results showed a steady decline in growth and in siderophore production per unit biomass with decreases in the O2/CO2 ratio at pH 7.8 and to a lesser extent at pH 6.0. The average percentage changes in siderophore production levels, relative to control were +0.8, -1.2, -18.2, and -40.6 at pH 6.0; -33.0, -50.4, -66.8, and -64.1 at pH 7.8 in the presence of O2CO2 levels of 18.0/3.0, 15.0/6.0, 12.0/9.0, and 9.0/12.0, respectively.
2

The dynamic behaviour of micro-organisms in continuous culture

Roberts, Jane Andrea Eileen January 1987 (has links)
No description available.
3

Microbial growth on 3-chloropropionic acid

Hughes, S. January 1988 (has links)
No description available.
4

Microbial infections of marine diesel engine lubricating oils - their significance and control

Genner, Colin January 1988 (has links)
No description available.
5

Interactions between microbial dynamics, water flow, and solute transport in unsaturated porous media

Yarwood, Rockie R. 20 August 2001 (has links)
Bioremediation in the vadose zone is unpredictable because of poor understanding of factors influencing microbial growth in this environment. A lab-scale experimental system was developed to examine, noninvasively, interactions between microbial growth, water flow, and solute transport in unsaturated porous media. Measurements of microbial colonization, and its impact on hydrology, were facilitated by using the luxCDABE-containing reporter bacterium Pseudomonas fluorescens HK44 and digital CCD imaging. Experiments were conducted in glass-walled two-dimensional flow cells (45 x 50 x 1 cm) packed with silica sand. Several bioengineering problems associated with chamber design and function required solution before microbial experiments were successful. These included: choice of materials for chamber components; development of sterilization, packing, and inoculation protocols; and development of procedures for data collection and chamber maintenance during experiments lasting several days. Bacterial growth was mapped daily by quantifying development of salicylate-induced bioluminescence. A model relating the rate of increase in light emission after induction successfully predicted microbial densities over four orders of magnitude (R��=0.95) provided that sufficient oxygen for the bioluminescence reaction was available. Total model-predicted growth during a one-week experiment agreed with potential growth calculated from the mass-balance of the system and previously established kinetic parameters (predicted, 1.2x10���� cells; calculated, 1.7x10���� cells). Although the rate of expansion of the colonized zone (and predicted populations in newly colonized regions) remained relatively constant, the proportion of the daily potential growth remaining within the chamber declined over time. Monitoring of bioluminescence revealed the development of an (hypothesized) anaerobic zone associated with microbial growth in the unsaturated porous media. Water content and flow streams were measured using light transmission. Accumulation of microbial growth modified the hydrologic properties of the sand causing up to 50% decrease in saturation within the colonized zone, diversion of flow around the colonized zone, and lowering (5 cm) of the capillary fringe height. Apparent solute velocity through the colonized region was reduced from 0.39 cm min����� (R��=0.99) to 0.25 cm min����� (R��=0.99). These experiments provide proof-of-concept for combining light transmission and bioluminescence technologies to study interactions between microbial growth and hydrology in unsaturated porous media. / Graduation date: 2002
6

Investigation into remediation of contaminated soil containing high sulphate and heavy metals concentration

Salami, Indah Rachmatiah Siti January 1999 (has links)
This study involved the investigation of a contaminated soil problem in Gateshead, UK. The site was previously a dumping area from industrial activities for over a hundred years and generated problems of high sulphate concentration and heavy metals in both the soil and the leachate which discharges into the River Tyne. The combination of such contaminants has not been widely investigated in the area of contaminated soil. The study was therefore divided into 2 parts, namely bioremediation of the contaminated soil and leachate treatment by reverse osmosis. The bioremediation study involved treatability tests which included slurry, microbial growth and column tests. The reverse osmosis study involved membrane fouling and leachate pre-treatment experiments. The bioremediation study stimulated the indigenous microorganisms by the addition of nutrients and carbon sources. The soil slurry and microbial growth tests determined the combination of nitrogen and phosphorus required to produce higher C02 evolution as an assessment of microbial activity. It was found in the column tests that the addition of a carbon source and appiopriate nutrient combinations resulted in a significant reduction of sulphate in both the leachate and the soil matrix. Furthermore, this was also accompanied by an increase in the microbial population in the soil matrix. It was also considered that- assimilatory sulphate reduction by microorganisms had taken place since H2S production could not be detected in the open system of the column. However, the high pH of the soil that was higher than 8 possibly caused H2S production undetected in this study. Zinc, manganesea nd copper,i n contrastw ere not reducedi n the soil matrix. Only arsenic showed significant reduction in the soil columns. Heavy metals were precipitateda nd were still presenti n high concentrationsin the leachatea nd would require further treatmenti n the liquid phase.T his was demonstratedb y the study of the use of a LPROM (Low PressureR everseO smosisM embrane)t o treat leachate from the contaminated soil. The reverse osmosis study showed that zinc and arsenic could be reduced by up to 86% and 97% respectively. Sulphate was also satisfactorily reduced up to 99%. However, the study on membrane fouling confirmed that the sulphate concentration was the main effect of fouling. Ferric chloride, aluminium sulphate, barium chloride and polyelectrolyte Zetag 92 were used for coagulation-flocculation in the pretreatment of the leachate. The study revealed that the sulphate concentration could only be reduced at the most by 43% using a FeC13, BaC12 and Zetag 92 combination. FeC13 showed better floc characteristics than alum whereas BaC12 improved sulphate removal but increased the turbidity in the supernatants. However, the use of BaC12 would significantly increase the cost of pretreatment. The study recommended a further investigation into the use of a range of readily available carbon, nitrogen and phosphorous sources in the soil column or at pilot-scale for designing a full-scale bioremediation system. Meanwhile, an investigation into other leachate pretreatment methods such as continuous microfiltration or anti-scalant addition was also suggested.
7

Assessment of Efficacy of Aseptic Techniques in Preventing Microbial Growth During Compounding of Sterile Preparations

Lamhang, Michael, Le, Daniel, Patel, Sunny, Lee, David January 2011 (has links)
Class of 2011 Abstact / OBJECTIVES: To determine if aseptic methods prescribed by the USP 797 are effective in preventing microbial growth when compounding intravenous medication. Sample size: 60 individual IV preparations, 20 for the control group and 20 per test group. METHODS: Sixty agar plates were made. The IV preparations for the control group were compounded with aseptic technique: washing hands with soap and water, wearing gloves, cleaning all ports with alcohol, and working in a laminar flow hood. A syringe was used to inject the water from the vial into the IV bag. This procedure was repeated in the same manner for Group A (no use of laminar flow hood) and Group B (no swiping of the injection ports with an alcohol swab), minus the aseptic technique in question. Once all 60 IV preparations were completed, a sterile inoculation tool was used to obtain a sample from the port of the IV bag. The plates were then inoculated. RESULTS: When compared to the control group, microbial growth in Group A was not significant (p=0.14). The contamination rate for Group B was also not significant (p=0.07). CONCLUSION: Solutions compounded using abbreviated techniques (not swabbing injection ports and not using laminar flow hood) are not more likely to be contaminated than when using all proper aseptic techniques simultaneously.
8

Modeling of Temperature Impacts on Fixed Film Microbial Growth and Nitrification Kinetics

Strombeck, Jacob January 2014 (has links)
Monod-type kinetic models, used in simulating microbial growth in biological treatment systems, suggest significant decreases of substrate utilization at lower temperatures. However, it is documented that performance of fixed film treatment systems are not hindered with declining temperatures. Previous studies at the Moorhead, MN, Wastewater Treatment Facility (WWTF) showed significant impacts of temperature on biofilm growth in its moving bed biofilm reactor (MBBR), and studies noted that at low temperatures more biomass was present. Previously, a series of kinetic bench-scale batch tests was performed to measure ammonium removal in the full-scale system. As part of this research, a diffusion based kinetic model was developed to simulate the bench-scale trials and determine if Monod kinetics and temperature corrections properly model fixed film systems. It was found that Monod kinetics and temperature corrections do apply to fixed film system as long as proper consideration is given to the change in biofilm characteristics.
9

Biofilm growth and colony variance in Streptococcus pneumoniae serotypes

Allegrucci, Magee. January 2007 (has links)
Thesis (Ph. D.)--State University of New York at Binghamton, Department of Biological Sciences, 2007. / Includes bibliographical references.
10

Survival of Microbial Indicators In constructed Wetlands

Vinluan, Edlin Artuz January 1996 (has links) (PDF)
Thesis (M.S. - Soil, Water and Environmental Science)--University of Arizona. / Includes bibliographical references (leaves 61-65).

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