Sulphate-reducing bacteria (SRB) are both ecologically and industrially significant in that they not only make a large contribution to detrital mineralization but also create massive corrosion problems. Methods for rapid detection and identification of two principle groups of SRB are described using phospholipid fatty acid biomarkers. Several Desulfobacter strains including 2ac9, AcBa, 3ac10, and 4ac11 as well as several other sulphate- and sulphur-reducing bacteria were examined for fatty acid biomarkers. The fatty acids 10Me16:0, cy 17:0(w7/8) and iso17:1w7c, iso15:1w7c are proposed as biomarkers for members of the genera Desulfobacter and Desulfovibrio respectively. A validation experiment was set up to verify use of the proposed biomarkers where a fermenter was enriched which made acetate and hydrogen available for sulphate-reduction. The SRB isolated from the system were found to be Desulfobacter and Desulfovibrio species and contained the correct proposed biomarkers. Titanium and steel tubes exposed to oxic, pumped Atlantic seawater were shown to recruit the SRB into biofilms. This was despite the fact that the seawater pumped through the pipes was oxygenated. Clearly both the metal and oxygen-utilizing bacteria created anaerobic microniches which permitted SRB to function even though obligately anaerobic. Further electrochemical experiments then demonstrated the corrosion effect of SRB in nominally 'aerobic' medium when protected from oxygen and supplied with carbon and energy by the facultatively anaerobic fermenter Vibrio natriegens. These data showed that the bacteria in batch culture conditions were more corroding than in continuous culture although this was independent of the bulk phase pH. The fastest corrosion rate however, was achieved when a continuous flow system lapsed into stagnating conditions. Cocultures with SRB produced slightly / faster corrosion rates than with Vibrio natriegens alone. Clearly the biomarker and electrochemical techniques may be used to quickly characterize a bacterial corrosion problem and then establish if SRB are a major component in the biofilm community. / Source: Dissertation Abstracts International, Volume: 48-12, Section: B, page: 3494. / Thesis (Ph.D.)--The Florida State University, 1987.

<p> Species from the genus <i>Chlamydia</i> are well known for their ability to infect a variety of organisms. They are obligate parasites that are widely distributed in nature and can withstand a variety of environmental stressors. Studies have recently demonstrated their prevalence in the environment lurking within protist reservoirs. The most characterized of these involves <i> Chlamydia</i> infections in the free-living amoebae <i>Acanthamoebae </i>. Recently, we have found that approximately half of wild collected <i> Dictyostelium discoideum</i> (social amoebae) are infected with <i> Neochlamydia</i>, a newly identified genus of the <i>Chlamydia</i> order. The goal of this project was to better understand the relationship between the bacteria <i>Neochlamydia</i> and the social amoebae Dictyostelium discoideum. Specifically, we asked whether <i>Neochlamydia </i> infections alter amoebae fitness using a collection of assays and environmental contexts. We found that <i>Neochlamydia</i> infected amoebae show subtle, but interesting, differences in fitness under a small subset of fitness contexts. We also attempted to transfer <i>Neochlamydia </i> to new amoebae hosts using 3 distinct strategies. Puzzlingly, we were unable to transfer <i>Neochlamydia</i> infections to new hosts, which leads us to speculate on how these infections are acquired in the wild.</p><p>

Source: Dissertation Abstracts International, Volume: 27-08, Section: B, page: 2583. / Thesis (Ph.D.)--The Florida State University, 1966.

The effects of disturbance on the marine sedimentary microbial community were studied using an integrated biochemical approach. Microbial biomass and community structure were determined by measuring the concentration of cellular components such as phospholipid fatty acids and muramic acid. Microbial growth was measured by the rate of tritiated thymidine into nucleic acid. A gas-chromatographic method for the measurement of poly-beta-hydroxyalkanoates was developed to allow assessment of the metabolic status of the microbial community. A method of exposing intact sediment cores to radiolabeled acetate was also developed. During the experimental validation of this method it was shown that the rate of acetate incorporation into phospholipid was a useful measure of microbial growth and that the ratio of the relative rate of acetate incorporation into phospholipid to the relative rate of acetate incorporation into poly-beta-hydroxyalkanoates reflected the short-term metabolic status of the microbial community. This ratio was observed to increase whenever sediments were disturbed. / Short-term (hours) changes within the marine sedimentary microbial community induced by three different disturbance events were compared. The disturbances were: sieving through a 1000 micron sieve, the feeding activities of sting rays, and the feeding activities of enteropnuest worms. Disturbance induced a series of time-dependent events. Microbial biomass and growth rates decreased after disturbance of the sediments. These declines were attributed to either predation or injury and death caused by abrasion. In contrast, the ratio of acetate incorporation into phospholipid to acetate incorporation into poly-beta-hydroxyalkanoates increased with disturbance. This increase was followed in time by increases in microbial growth rates and finally microbial biomass. The microbial community structure was also observed to shift following the disturbances. / Sediments were maintained in laboratory microcosms following sieving. After five days microeucaryotes and aerobic procaryotes had declined while the biomass of anaerobic procaryotes increased. Growth rates were depressed and the measures of community metabolic status indicated the organisms were under metabolic stress and were possibly undergoing starvation. / Source: Dissertation Abstracts International, Volume: 48-07, Section: B, page: 1887. / Thesis (Ph.D.)--The Florida State University, 1986.

The physical environment in the cryptoendolithic habitat in Antarctica were investigated using two complementary approaches: field measurements and theoretical models. / Light, air temperature, snow, wind and rock temperature and moisture on Linnaeus Terrace, Antarctica, were monitored for three years through a satellite-mediated automatic weather station. These data were coupled with existing information on light, temperature, and moisture requirements and used to estimate the period of biological activity. Metabolic activity in the community is restricted to the period from mid November to mid February, with the total number of hours of biological activity less than about 1000 hours per year. / The measured temperature data were supplemented through the construction of a computer model of the temperature regime. This model enabled the parameters affecting the horizontal and altitudinal distribution of the community to be examined. Colonization is possible on surfaces with zenith angle less than $15\sp\circ.$ At greater zenith angles, colonization is restricted to surfaces with azimuth angles less than $135\sp\circ$ or greater than $225\sp\circ.$ The upper elevational limit of the community is less than 2500 m. The thermal regime probably does not influence the zonation of the community within a rock. / The light regime within the community was investigated though the development of a general computer model of light transmission in close-packed particulate media. The apparent extinction coefficients in dry colonized rocks varies from 1.5 to 3.0 mm$\sp{-1},$ depending on the amount of iron-oxide in the crust and the degree of colonization. Saturating amounts of water decrease the extinction coefficient to about 65% of its dry value. In absolute numbers, the maximum irradiance at the top of the Hemichloris zone is about 1 $\mu{\rm M}$ photons ${\rm m}\sp{-2}$ ${\rm s}\sp{-1}$ when dry, 10 $\mu{\rm M}$ photons ${\rm m}\sp{-2}$ ${\rm s}\sp{-1}$ when wet. Because of the low light levels, it is expected that the eukaryotic microorganisms in the community are restricted to only a few cell divisions a year. / Source: Dissertation Abstracts International, Volume: 48-07, Section: B, page: 1888. / Thesis (Ph.D.)--The Florida State University, 1987.

Source: Dissertation Abstracts International, Volume: 32-03, Section: B, page: 1721. / Thesis (Ph.D.)--The Florida State University, 1971.

Source: Dissertation Abstracts International, Volume: 30-02, Section: B, page: 0753. / Thesis (Ph.D.)--The Florida State University, 1968.

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