The object of this thesis was to examine microbial interactions in offshore crude oil storage systems with special reference to the role played by the sulphate-reducing bacteria (SRB). The aim was to characterise the SRB present in such systems; to isolate and characterise crude oil-degrading bacteria and to develop simple models of the system. SRB were shown to be present in samples from offshore by the detection of high levels of SRB and sulphide, and of depleted sulphate levels. SRB were enriched for, isolated and characterised from offshore oil storage facilities and pure cultures of the organisms <i>Desulfovibrio desulphuricans, Desulfovibrio sapovorans, Desulfobacter postgatei</i> and <i>Desulfobulbus propionicus</i> were isolated. <i>Desulfobacter</i> was shown to be the key organism in this environment, responsible for the terminal oxidation of acetate produced from the incomplete oxidation of higher fatty acids by the <i>Desulfovibrio</i> spp. and the <i>Desulfobulbus</i>. The enrichment, isolation and partial characterisation of oil-degrading bacteria of the genera <i>Pseudomonas</i> and <i>Micrococcus</i> was also carried out. These organisms were shown to use both aliphatic and aromatic components of crude oil. The breakdown of hydrocarbons provides both the anaerobic conditions and carbon sources necessary for the growth of SRB. Liquid and gel-stabilised model systems in which both the temporal and spatial development of oil-degrading communities (including SRB) were constructed.

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Thesis (Ph. D.)--Miami University, Dept. of Microbiology, 2009. / Title from second page of PDF document. Includes bibliographical references (p. 195-218).

Anthropogenic freshwater salinization, which is caused by numerous human activities including agriculture, urbanization, and deicing, impacts an estimated 37% of the contiguous drainage area in the United States. High salt concentrations in brackish and marine environments (~1,500 – 60,000 µS cm-1) influence aquatic bacteria. Less is known about the effects of freshwater salt concentrations (≤ 1,500 µS cm-1) on bacterial ecology, despite the pervasiveness of freshwater salinization. Bacteria perform many fundamental ecosystem processes (e.g. biogeochemical cycling) and serve as indicators of human health risk from exposure to waterborne pathogens. Thus, to understand how salt pollution affects freshwater ecosystems, there is a critical need to understand how freshwater salinization is impacting bacterial ecology. Using a series of controlled mesocosm experiments, my objectives were to determine how (1) survival of fecal indicator bacteria (FIB), (2) the diversity of native freshwater bacterial communities, and (3) bacterial respiration and nutrient uptake rates responded across a freshwater salinity gradient of different salt profiles. Survival rates (t90) of Escherichia coli, the EPA recommended freshwater FIB, increased by over 200% as salinity increased from 30 to 1,500 µS cm-1. Survival rates were also significantly higher in water with elevated Mg2+ relative to other base cations, suggesting that different salt sources and ion profiles can have varied effects in FIB survival. Thus, freshwater salinization could cause accumulating concentrations of FIB even without increased loading, increasing the risk of bacterial impairment. Diversity of native bacterial communities also varied across a freshwater salinity gradient, with a general increase in species richness as salinity reached 1,500 µS cm-1. Community variability (β-diversity) was greatest at intermediate salinities of 125 – 350 µS cm-1 and decreased towards the upper and lower extremes (30 and 1,500 µS cm-1, respectively). These diversity patterns suggest that osmotic stress is an environmental filter, but filtering strength is lowest at intermediate salinities causing a change from more deterministic to more stochastic assembly mechanisms. Different salt types also produced distinct bacterial community structures. Lastly, bacterial respiration doubled as salinity increased to 350 – 800 µS cm-1, revealing a subsidy-stress response of bacterial respiration across a freshwater salinity gradient. Corresponding changes in nitrogen and phosphorus uptake increased N:P ratios in ambient water, especially in mesocosms with elevated Ca2+, which could affect nutrient limitation in salinized streams enriched with Ca2+. Bacterial community structure based on Bray-Curtis dissimilarity was not correlated to pairwise changes in respiration rates but was linked to net nitrogen and phosphorus uptake after five days. Collectively, these results establish that freshwater salinization alters bacterial ecology at the individual population, whole community, and ecosystem process scales. Further, different salt types (e.g., CaCl2, MgCl2, NaCl, KCl, sea salt) had varying effects on bacteria at all levels and should be considered when predicting the effects of salinization on freshwater ecosystems. Developing more nuanced salt management plans that consider not only amount, but different types, of salts in freshwaters could help improve our ability to predict human health risk from waterborne pathogens and mitigate/ reduce salinity-induced impacts to freshwater ecosystem processes and services. / Doctor of Philosophy / Humans rely on streams, rivers, and lakes for many services including transportation, recreation, food, and clean drinking water. Despite our reliance on freshwater ecosystems, human activity has significantly degraded freshwater resources worldwide. Recently, salt pollution caused by human activity on land, known as freshwater salinization, has emerged as a widespread water quality issue. Numerous human activities including agriculture, urbanization, resource extraction, and deicing have increased freshwater salt concentrations in 37% of the United States' contiguous drainage area. Large changes in salinity (i.e. from freshwater to oceanic salinities) are known to affect bacteria that perform many important ecological functions, such as nutrient cycling and water purification, while the effects of smaller changes in salinity more typical within the freshwater range are unknown. I used controlled laboratory experiments to determine how freshwater salinization affects (1) survival rates of Escherichia coli, (2) diversity of native bacterial communities, and (3) bacterial nutrient cycling. My results revealed that freshwater salinization can significantly increase how long E. coli survive in freshwater. E. coli are used to detect the presence of waterborne pathogens and reduce human health risk. Thus, freshwater salinization might reduce the reliability of E. coli as an indicator of waterborne pathogens as well as increase concentrations of bacterial that are potentially harmful to human health in freshwater. Additionally, freshwater salinization affected bacterial diversity by altering the ways in which bacterial communities form. In general, the number of bacterial species present increased as salinity reached the upper freshwater limit, but communities were most variable at intermediate freshwater salt concentrations. These diversity patterns suggest that different salt concentrations can either cause or reduce stress in bacteria, resulting in significantly different bacterial communities. Lastly, moderate increases in freshwater salt concentrations doubled bacterial respiration and nutrient uptake rates. Bacterial respiration influences how energy flows through ecosystems, and freshwater salinization could potentially alter this process. Different salt types also had different effects of bacterial ecology. Collectively, my results establish that freshwater salinization impacts bacteria at the individual, community, and ecosystem levels.

The vagina is one organ of the body which has not been studied exhaustively. Moreover, most of the studies found in the contemporary literature have been performed on women affected by a variety of genital diseases. In the present study the vaginal epithelium was examined with a histological method, morphometry, whereby cyclical changes related to hormonal variation during the menstrual cycle were demonstrated. Determination of the quantity of estrogen receptors in the vaginal epithelium on two occasions during the menstrual cycle revealed a significantly greater number in the follicular than in the luteal phase. The results of these studies indicate the presence of a menstrual variation in the vaginal epithelium comparable to that in the endometrium. Phenoxymethylpenicillin (pcV) was used as a marker substance to study the dynamics of the transport mechanisms into the vagina. PcV was found to accumulate in the vaginal fluid and high concentrations persisted for a long period of time. In hysterectomized women, the appearance of pcV in the vaginal fluid followed the same pattern. Consequently, the substance is transported through the vaginal wall and need not enter with the secretions from the internal genitalia. The greatest concentration of pcV was in the distal portion of the vagina, possibly due to the specific internal circulation of fluid within the vagina. Bacterial vaginosis as an example of an ‘ecological disease’ has been studied with regard to the formation of endotoxin, a constituent of the cell wall of Gram- negative bacteria. Large amounts of endotoxin were found and the clinical implication of this finding has been pointed out. Furthermore, the influence of pcV on the vaginal microbial flora of healthy women has been investigated. A change from a situation with predominance of lactobacilli to the appearance of Gram-negative rods was observed. In one of the women the lactobacilli disappeared completely and were replaced by E. coliand high levels of endotoxin in the vaginal fluid were found. This study demonstrates the complexity of the ecological balance of the vaginal microbial flora and illustrates the difficulty of defining a ‘normal’ vaginal condition. Is there any unquestionable state of ‘normality’ even in a healthy woman free from symptoms of genital disease? / <p>S. 1-22: sammanfattning, s. 25-64: 6 uppsatser</p> / digitalisering@umu