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Life history of Philophthalmus megalurus (Cort, 1914) in western OregonMcMillan, Toni Anne 01 January 1971 (has links)
The specific identification of a megalurous cercaria found in the snail Oxytrema plicifera was accomplished by completing the life cycle in the laboratory. This species is compared with the eastern Philophthalmus megalurus and P. gralli with which it was once confused. The eggs, miracidia, and rediae of the Oregon species were found to be similar to those of the above species. The body and organ sizes and sucker ratios for the cercariae and adult stages obviously indicate that the Oregon species is Philophthalmus megalurus.
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Polyphasic examination of microbial communities in soils contaminated with organic pollutantsJuck, David F. January 2001 (has links)
No description available.
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Polyphosphates and microbial uptake of phosphorus : studies with soil and solution cultureFleming, Nigel Kevin. January 1992 (has links) (PDF)
Includes bibliographical references
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Osmoadaptation mechanisms of cyanobacteria and archaea from the stromatolites of hamelin pool, Western Australia.Goh, Falicia Qi Yun, Biotechnology & Biomolecular Sciences, Faculty of Science, UNSW January 2007 (has links)
The stromatolites of Shark Bay Western Australia, located in a hypersaline environment, is an ideal biological system for studying survival strategies of cyanobacteria and halophilic archaea to high salt and their metabolic cooperation with other bacteria. To-date, little is known of the mechanisms by which these stromatolite microorganisms adapt to hypersalinity. To understand the formation of these sedimentary structures, detailed analysis of the microbial communities and their physiology for adaptation in this environment are crucial. In this study, microbial communities were investigated using culturing and molecular methods. Phylogenetic analysis of the 16S rRNA gene was carried out to investigate the diversity of microorganisms present. Unique phylotypes from the bacteria, cyanobacteria and archaea clone libraries were identified. Representative cyanobacteria isolates and Halococcus hamelinensis, a halophilic archaea isolated from in this study, were the focus for identifying osmoadaptation mechanisms. The presence of osmolytes in these microorganisms was detected by Nuclear magnetic resonance spectroscopy (NMR). It was found that the cyanobacterial isolates studied utilised different osmolytes. Glucosylglycerol, unique to marine cyanobacteria was not identified; instead various saccharides, glycine betaine and TMAO were the predominant solutes present. Thus cyanobacteria are likely to possess more complex mechanisms of adaptation to osmotic stress than previously thought. Findings here also indicated that H. hamelinensis accumulates glycine betaine and glutamate instead of potassium ions. DNA molecular methods were employed to identify candidate genes for the uptake of osmoprotectants. Three putative glycine betaine transporters from Halococcus hamelinensis were identified. Functionality of one of these glycine betaine transporters was determined by complementation studies. For the first time, an archaeal glycine betaine transporter was shown to be successfully complemented in a glycine betaine transport deficient mutant (E. coli MKH13). This study has increased our understanding of how microorganisms co-exist in fluctuating environments in response to solubilisation/precipitation or dilution/evaporation processes, resulting in a hypersaline environment. It also provides an excellent platform for the identification of any novel osmolytes/compatible solutes that might have been produced by these microorganisms that have been isolated for the first time from stromatolites.
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The isolation, growth and survival of thermophilic bacteria from high temperature petroleum reservoirsGrassia, Gino Sebastian, n/a January 1995 (has links)
The microbial ecology of 45 high temperature (> 50 ° C) petroleum reservoirs was
investigated by isolating and characterizing bacteria that were present in their produced
fluids. Initial work was aimed at selecting a suitable high temperature petroleum
reservoir for the study of natural microbial populations. Experimental work then
focussed on establishing the physico-chemical conditions that prevail in the selected
reservoir and on developing media and enrichment conditions for the isolation of
microorganisms indigenous to the reservoir. The ability of reservoir bacteria to grow
and survive under the physical and chemical conditions found in the selected reservoir
was used to assess the likelihood of an indigenous origin for these bacteria.
The petroleum reservoir selected for study was the Alton petroleum reservoir (SW
Queensland, Australia). It was established that most of the physico-chemical conditions
in the Alton reservoir had remained unchanged since oil recovery began. The stability
of redox conditions (90 mV) in the reservoir over its operating life was identified as an
important factor in the coexistence of strict aerobic and strict anaerobic bacterial
populations within the reservoir. An important change that has occurred in the Alton
reservoir over its operating life because of oil recovery was an increase in water pH
from 6.41 to 8.42 as a result of carbon dioxide loss (1.36 atm to 0.0134 atm) from the
reservoir.
Development of novel enrichment procedures that simulated Alton reservoir conditions
led to the isolation of previously unreported aerobic and anaerobic populations of
thermophilic bacteria. The aerobic bacteria isolated were identified as either endosporeforming
heterotrophic bacteria from the genus Bacillus or nonspore-forming
heterotrophic bacteria resembling members of the genus Thermoleophilum. All aerobes
grew on carbon sources such as acetate and n-heptadecane that are normal constituents
of the reservoir. The anaerobic bacteria isolated were characterized as sheathed
fermentative bacteria from the order Thermotogales or non-sheathed fermentative
bacteria. In parallel studies, the natural microbial populations in other reservoirs were
investigated and I concluded that fermentative microorganisms were common
inhabitants of high temperature petroleum reservoirs. The isolation of fermentative
bacteria from these high temperature petroleum reservoirs established that fermentative
bacteria are a fourth major microbial group, together with hydrocarbon-oxidizers,
sulphate-reducers and methanogens, to be reported in petroleum reservoirs. The
fermentative bacteria use organic nutrients and carbohydrates, but not contemporary
crude oil as the principal nutrient source within reservoir waters.
The thermophilic bacteria isolated from Alton petroleum reservoir demonstrated growth
characteristics such as temperature (optima 50-70 ° C and range 37-85 ° C), pH (optima
6.0-9.0 and range 5.0-9.0 and salinity (optima 0-15 g per litre and range 0-30 g per
litre), that were consistent with conditions encountered in the Alton reservoir
(temperature 75 � C, pH 8.5 and TDS 2.7 g per litre). The isolated bacteria also
demonstrated a number of characteristics that might enable them to survive adverse
conditions that could be encountered in a petroleum reservoir environment. The
characteristics that contribute to aerobic bacteria surviving in and overcoming periods
of oxygen limitation include well-documented processes such as sporulation, by
Bacillus spp., and microaerophily. The characteristics that contribute to fermentative
bacteria surviving were: (1) a natural tolerance to reservoir physico-chemical
fluctuations, (2) an ability to remain viable when metabolic activity was suppressed to
very low rates by the growth-limiting conditions imposed, and (3) possible formation of
viable ultramicrobacteria (UMB). Formation of UMB (bacteria smaller than 0.3 |im) by
thermophilic bacteria has not been reported previously.
The recovery of thermophilic UMB by filtration from the Alton reservoir water
indicates that these bacteria occur in natural habitats. This study found the formation of
thermophilic UMB and their survival characteristics differed considerably from that
reported for the mesophilic, marine bacterium Vibrio sp. DWI. Unlike mesophilic
marine bacteria, thermophilic bacteria did not always respond to nutrient deprivation by
forming UMB and that these UMB did not show any increased ability to survive in the
face of adverse conditions. Although the formation of UMB as part of routine cell
growth and division was not demonstrated directly in this study, circumstantial
evidence suggests that they form part of a natural life cycle. The exact conditions that
result in UMB formation and their role in survival remain unresolved.
The capacity of nonspore-forming indigenous populations from Alton to survive sudden
shifts in environmental conditions that might result from common oilfield operations
was poor. Such operations were demonstrated to be inhibitory or lethal to Alton
reservoir bacteria. It also was concluded that such oilfield operations suppress
indigenous microbiota. However, the impacts of most oilfield operations within a
reservoir are likely to be confined to the immediate area surrounding injection and
producing wells. Minimizing the localized effects of oilfield practices on indigenous
reservoir populations will lead to the better management of undesirable microbial
activity in reservoirs such as H2S formation (souring) and facilitate development of
better microbially mediated oil recovery process. This study showed that selected
reservoir isolates possess characteristics which are suitable for in situ biotechnological
applications such as microbially enhanced oil recovery (MEOR). Characteristics
favourable for enhanced oil recovery include a capability for UMB formation, which
would enable better dispersion, and resistance to high concentrations of reservoir
components such as calcium, magnesium, strontium, heavy metals and hydrocarbons.
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The microbial ecology of equine laminitis of alimentary originMilinovich, Gabriel Unknown Date (has links)
No description available.
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Linking soluble C to microbial community composition and dynamics during decomposition of ����C-labeled ryegrassMcMahon, Shawna K. 13 January 2004 (has links)
Ryegrass residue consists of three main C fractions: readily available soluble C,
intermediately available cellulose and hemicellulose, and slowly available lignin.
Changes in chemical composition during decomposition influence rate of degradation as
well as composition of the microbial community involved. Use of ����C-labeled plant
material coupled with analysis of phospholipid fatty acids (PLEA) by isotope ratio mass
spectrometry results in a powerful tool for linking microbial community structure and C
cycling processes during decomposition.
The objective was to investigate the role of soluble C in the decomposition of
ryegrass straw. We wanted to determine (i) if the presence or absence of labile C in straw
affects C mineralization by the microbial community, (ii) if community structure would
differ based on the presence of labile C, and (iii) if community structure would shift as
decomposition progressed.
Residue was added to soil microcosms at rates that reflect field loads. Treatments
were unleached straw (US), leached straw (LS), and leachate (L), plus an unamended
control (C). Added substrates had ������C values between 120% and 180% the native soil
signature was 26%. Respiration was measured every 4 to 6 hours for the first 5 d, and
weekly thereafter. Destructive sampling took place after 0.6, 1 .6, 1 5, 1 8. 50, and 80 d of
incubation and microbial biomass '��C (MBC) and PLFAs were analyzed.
The soluble component of ryegrass straw strongly influenced C mineralization
and assimilation, as well as microbial community composition and dynamics. CO2
evolution rates and ����C signatures were similar in US and L during the first 3 d of
incubation. Most soluble C from leachate was consumed during that time, indicated by
the rapid decrease in ������C value of CO2 evolved from L treatment. Substrate-derived C
moved quickly into and through the microbial biomass.
Distinct temporal shifts occurred in community composition. Early communities
in amended soils were dominated by short and branched-chain PLFAs such as 15:Oa.
Later samples contained more complex and longer PLFAs. 19:Ocy was an indicator for
late succession communities in US and L, and 18:2w6,9 characterized late samples in LS.
Soluble C affected when the temporal shift occurred in LS and L, communities shifted
earlier than in US. Lipids were differentially enriched with ����C. Fungi, as indicated by
18:2w6,9, were more effective at incorporating substrate C into cellular lipids, as this was
the most highly labeled of all PLFAs. / Graduation date: 2004
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N₂ fixation and denitrification in a floodplain forest in central Amazonia, BrazilKreibich, Heidi, January 2002 (has links) (PDF)
Thesis (Dr. rer. nat.)--Philipps-Universität Marburg, 2002. / Title from PDF t.p. (viewed on Apr. 24, 2007). Includes bibliographical references (p. 143-163).
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Quantification and Ecological Perspectives on Cyanophage and Aquatic VirusesMatteson, Audrey Renee 01 May 2011 (has links)
The field of viral ecology is still relatively new and many processes by which viruses influence hosts are still widely unknown. One problem is that there are few standardized techniques in virus ecology, making comparisons of data very difficult. To better understand the methodology, we first set out to make a video showing the process for the viral production assay using the “dilution and reoccurrence” method, which has become the standard to analyze production rates in aquatic ecosystems. Using this method, we also determined the production rates of viruses during a seasonal pelagic phytoplankton bloom during a cruise off the coast of the north island of New Zealand in the subtropical Pacific Ocean. Other biotic and abiotic parameters were also compared throughout the bloom. Production rates were within normal ranges, but showed that viruses were very important for the remobilization of nutrients in the nitrogen-limited system.
It is well known that the cyanobacterial genera Synechococcus and Prochlorococcus thrive in the world’s oceans with Synechococcus and other cyanobacterial species also succeeding in freshwater ecosystems. Cyanophages are viruses which infect cyanobacteria and many studies have investigated their diversity using the portal vertex g20 gene in the Cyanomyoviridae family. Although we know that there is significant genetic richness in these phage in marine and freshwater environments, information on their numerical distributions is rare. Using quantitative PCR with the g20 gene, we determined that cyanomyoviruses are ubiquitous and abundant in the Atlantic and Pacific Oceans as well as within Lake Erie. Using statistical analyses we were able to find correlations between cyanomyoviruses and other biotic and abiotic parameters: in the Sargasso Sea, cyanomyovirus abundance correlated well to biology, but in the other systems there was no significant correlation to biological abundances. This suggests that the constraints of this group of viruses may be different in different aquatic realms.
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Anthropogenic heavy metals in organic forest soils : distribution, microbial risk assessment, and Hg mobility /Åkerblom, Staffan. January 2006 (has links)
Thesis (doctoral)--Swedish University of Agricultural Sciences, 2006. / Thesis documentation sheet inserted. Appendix reprints four manuscripts co-authored with others. Includes bibliographical references. Also issued electronically via World Wide Web in PDF format; online version lacks appendix.
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