No description available.

No description available.

A culture collection of clonal, axenic cultures of 35 Arthrospira strains and five strains, which were duplicate subcultures of the original isolates, was established. In addition, eight morphological mutants were isolated from cultures of these strains. All strains are different from those belonging to the genus Spirulina as concluded from TEM and PyMS studies. All Arthrospira strains, duplicates and different morphotypes were screened for variation in morphological, ultrastructural, physiological and biochemical characters for taxonomic purposes. Special emphasis was put on the analysis of factors which influence the morphology of the trichome helix, as this is the feature most characteristic forArthrospira strains. For example, the orientation of coiling was found to be influenced by genetic drift or the growth temperature, but can also be reversed by mechanical impact. Studies were also made on the ability to utilize sugars for growth. None of the strains grew on sucrose, but many grew on glucose and/or fructose. Growth in the presence of sucrose under photoheterotrophic conditions required an adaptation process, though sucrose is not being utilized for growth. Analysis of fatty acid composition of all strains revealed quantitative differences between strains, most markedly in the unsaturated fatty acid fraction. Repeat experiments showed the same results each time, indicating the value of this approach for identification purposes. Similarly, lectin-binding to cell surface structures proved to be a useful approach for differentiation between strains. Analysis of the whole cell composition by pyrolysis mass spectrometry (PyMS) did not confirm the clusters based on other phenotypic characters, but showed that there is a high similarity between duplicate strains or different morphotypes derived from the same stock. Numerical analysis of the data for 28 characters resolved the helical strains in two phenotypic clusters which show a high correlation to the two molecular clusters based on ARDRA of the ITS of the same set of strains. The helical trichome morphology of the strains showed the highest correlation to either of the clusters. Comparison of species descriptions and morphological characters of the strains, as determined in the presented work, indicate, that phenotypic cluster I is composed of Arthrospira maxima, A. fusiformis and A. indica, while A. platensis forms phenotypic cluster II

Twenty-two different unialgal clonal isolates have been obtained at random for experimental purposes over a period of about one year. Also, during this period, at least 12 other species or strains have been isolated into unialgal cultures which had not yet been identified and/or significantly cleared of heterotrophic contaminants.

This thesis reports the effect of the non-toxic cyanobacterium Oscillatoria agardhii CYA29 and its spent medium on the cell-bound toxin levels in Microcystis aeruginosa PCC7820 and Nodularia sp. PCC7804. Microcystin levels were elevated when O. agardhii or its spent medium were added to cultures of M. aeruginosa PCC7820. This effect was also observed for two nodularin variants in Nodularia PCC7804. However, growth of M. aeruginosa in its own spent medium did not lead to elevated microcystin levels. Some Gram-negative bacteria use quorum sensing, the determination of population density by pheromones, to regulate the expression of traits in a density dependent manner. The presence of the bacterial pheromones, acyl-homoserine lactones (AHLs), was investigated in cyanobacteria and a simple and fast synthesis for AHLs employed. No AHLs have been found in the cyanobacterial species tested, neither by Chromobacterium violaceum CV026 nor by Escherichia coli HB101 pUCD607 bioassay. No changes in dry weight or microcystin concentration were observed in M. aeruginosa PCC7820 grown in the presence of the AHL N-hexanoyl-DL-homoserine lactone. The activity of the spent medium of O. agardhii CYA29 was retained when it was heated up to 100°C for 20 min, frozen or freeze-dried. Molecular weight cut-off filtration showed the active compound to be less than 1 kD in size. The active component could not be extracted by dichloromethane or methanol, and activity was lost upon acidification. A small peptide of five amino acid moieties was isolated from an active fraction of the spent medium, four of which have been identified by 1H NMR to be serine, glycine, alanine, and the modified serine(thiazole). To my knowledge this is the first report of serine(thiazole) in natural products and the first thiazole containing peptide from O. agardhii.

Indiana University-Purdue University Indianapolis (IUPUI) / This project examines the impact of confounding variables that have limited the accuracy of remotely predicting phycocyanin in three Indiana drinking and recreational water reservoirs. In-situ field reflectance spectra were collected from June to November 2006 over a wide range of algal bloom conditions using an ASD Fieldspec (UV/VNIR) spectroradiometer. Groundtruth samples were analyzed for chlorophyll a, phycocyanin, total suspended matter, and other water quality constituents. Previously published spectral algorithms for the detection of phycocyanin were evaluated against lab measured pigment concentrations using linear least squares regression. Algorithm performance varied across study sites (best performing models by reservoir resulted in r2 values of 0.32 to 0.84). Residuals of predicted versus measured pigment concentrations were analyzed against concentration of potential confounding water constituents. Residual analysis revealed optically active constituents contributed between 25% and 95% of original phycocyanin model errors. Inclusion of spectral variables into models to account for significant confounders resulted in improved spectral estimates of phycocyanin (r2 = 0.56 to 0.93).

The work in this thesis is an extension of a large study carried out by this college at Rothamsted Experimental Station (J. Featherstone-Witty, Ph.D thesis, 1974; with Keay, and Froggatt in press) and was aimed at scaling down the fieldwork to lysimeter investigations in order to elucidate the true value of algal inoculation as a replacement for synthetic fertilizers. Two lysimeters (each measuring 5m. x 3m.) were constructed above ground on concrete rafts with a built in facility to collect drainage water from the four quarters of each lysimeter. Both units were filled with calcareous soil (pH. 8). Each unit was divided into 4 treatments and sown to spring wheat. Previous indications were that this variety would benefit more from algal release of nitrogen than winter wheat because of a later maturation, and hence greater likelihood of the ears receiving nitrogen released from algal cells during late summer. A continuous record was kept of variations in soil, crop and drainage water nitrogen together with surface nitrogen fixation measurements (using the acetylene reduction technique), so that estimates of the efficiency of algal inoculation, to increase soil-N levels, could be made. Laboratory studies have suggested nitrogen fixation occurs only in soils low in nitrogen (less than about 4ppm) and algal cells apparently release very little extracellular nitrogen when grown on solid surfaces. These low levels of nitrogen would not support crop yields equivalent to those achieved by the application of synthetic fertilizers. Results from the two year lysimeter study suggest no improvement in crop yield for the algal inoculated treatments, compared with the controls, though total crop nitrogen, for the algal treatments was approximately 7% higher than the fertilizer treatments and 60% higher than the mean value for the two controls; ear nitrogen was as much as 46% higher than the controls. Algal inoculation, together with herbicide application, proved the best treatment, improving both crop dry weight and nitrogen composition significantly.

No description available.

The purpose of this investigation is to determine the effect of varying geosmin concentrations on the growth of selected cyanophytes which did not produce a notable odor in culture.

This investigation has determined the presence of biological nitrogen fixation in two reservoirs in the southwestern United States: Lake Arlington and Lake Ray Hubbard. Subsequent tests have gathered baseline data on the effects of various biological, chemical, and physical parameters on in situ nitrogen fixation in these reservoirs. Of specific importance is the relationship between nitrogen fixation arid occasional blooms of blue-green algae which produce such problems as testes and odors in these water-supply impoundments.