Oscillatoria

Abstract: From information on pollution-tolerant algae compiled from reports from 165 authors, the genera and species most often referred to as significant fall into a relatively stable series. Diatoms, pigmented flagellates, green, and blue-green algae are all well represented among the pollution-tolerant genera and species. The top 8 genera are Euglena, Oscillatoria, Chlamydomonas, Scenedesmus, Chlorella, Nitzschia, Navicula, and Stigeoclonium, and the top 5 species, Euglena viridis, Nitzschia palea, Oscillatoria limosa, Scenedesmus quadricauda, and Oscillatoria tennis. In some genera, e.g., Euglena, a single species is far more significant than all others as a pollution-tolerant form. In other genera, e.g., Oscillatoria, only a slight difference distinguishes the pollution tolerance of 2 or more species. Algal genus and species pollution indices arc presented for use in rating water samples with high organic pollution.

Abstract: The production of microcystins (MC) from Microcystis aeruginosa UTEX 2388 was investigated in a P-limited continuous culture. MC (MC-LR, MC-RR, and MC-YR) from lyophilized M. aeruginosa were extracted with 5% acetic acid, purified by a Sep-Pak C18 cartridge, and then analyzed by high-performance liquid chromatography with a UV detector and Nucleosil C18 reverse-phase column. The specific growth rate (m )o fM. aeruginosa was within the range of 0.1 to 0.8/day and was a function of the cellular P content under a P limitation. The N/P atomic ratio of steady-state cells in a P-limited medium varied from 24 to 15 with an increasing m. The MC-LR and MC-RR contents on a dry weight basis were highest at m of 0.1/day at 339 and 774 m gg 21 , respectively, while MC-YR was not detected. The MC content of M. aeruginosa was higher at a lower m, whereas the MC-producing rate was linearly proportional to m. The C fixation rate at an ambient irradiance (160 microeinsteins m 22 s 21 ) increased with m. The ratios of the MC-producing rate to the C fixation rate were higher at a lower m. Accordingly, the growth of M. aeruginosa was reduced under a P limitation due to a low C fixation rate, whereas the MC content was higher. Consequently, increases in the MC content per dry weight along with the production of the more toxic form, MC-LR, were observed under more P-limited conditions. The bloom of cyanobacterium Microcystis aeruginosa is a ubiquitous phenomenon in eutrophic lakes and reservoirs in many countries of the world. Many strains of Microcystis are known to produce cyanobacterial hepatotoxins called microcystins. The toxin, a soluble peptide, is lethal to many kinds of aquatic organisms and damages zooplankton, fish (14), and the liver of higher animals (2, 22). Many studies on the effects of environmental factors on microcystin production by cyanobacteria have been conducted with Microcystis (7, 13, 19, 20, 22‐24), Anabaena (15, 16), Oscillatoria (17), and Synechocystis (11) species. The toxin of M. aeruginosa is at a maximum at light intensities between 40