Bioactive compound production by thermophilic and thermotolerant cyanobacteria (blue-green algae)

A thermotolerant species of Phormidium produced extracellular anti-microbial material during batch culture. Although this material was inactive when screened against a number of other cyanobacteria, it inhibited the growth of a wide range of Gram-positive and Gram-negative heterotrophic bacteria, Candida albicans and Cladosporium resinae.The authors are with the Department of Biological Sciences, University of Dundee, Dundee DD1 4HN, UK     

Studies on mixed mass cultivation of Anabaena spp. (nitrogen-fixing blue-green algae, cyanobacteria) on a large scale

Studies on mixed mass cultivation of Anabaena spp. on a large scale (5170m²) were conducted continuously for 3 years. Under the continental monsoon climate in northern subtropics (30°N, 115°E), 7–11 g dry weight m⁻² day⁻¹ of microalgal biomass on average was harvested in simple plastic greenhouses in the effective growth days during the warmer seasons. The maximum productivity was 22 g m⁻² day⁻¹ in the middle of summer. Observations on the productive properties of strains of Anabaena spp. indicated that they were different from and could compensate for each other in their productivities and adaptations to the seasonal changes. With different lining materials (PVC sheets, concrete, sand and soil) in the culture ponds, no significant variation of productivity was found, but bubbling with biogas in the middle of the day and the application of some growth regulating substances (2,4-D, NaHSO₃ and extracts of oyster mushroom spawn) was able to improve the production. The cost of microalgal biomass in this way was around 0·75–1·0 US dollar(s) per kilogram.     

Composition of cyclic peptide toxins among strains ofMicrocystis aeruginosa (blue-green algae,cyanobacteria)

The distribution of the cyclic heptapeptide toxin, microcystin, was studied among 31 strains of Microcystis aeruginosa. Microcystins-RR, -YR and -LR were detected in fifteen strains and microcystin-LR was in two strains, but no toxin was found in fourteen strains. All three toxins were detected in all 12 strains belonging to the large cell-size group recognized by cell size and allozyme genotype. This pattern of toxin composition is compatible with that of M. viridis. The small cell-size group showed variation in the toxin composition as in the case of allozyme genotype.     

Phycochromes b and d: their occurrence in some phycoerythrocyanin-containing blue-green algae (cyanobacteria)

Abstract
Phycochromes b and d, two types of photoreversibly photochromic pigments previously extracted from the blue-green alga Tolypothrix distorta , which contains phycoerythrocyanin, have now been found in three Anabaena strains also containing phycoerythrocyanin. Tests for the presence of phycochromes b and d in a number of blue-green algae lacking phycoerythrocyanin have been negative. The possibility that phycochrome b-type absorbance changes are due to changes in the α-subunit of phycoerythrocyanin is discussed.     

Hydrogen metabolism in the facultative anoxygenic cyanobacteria (blue-green algae) Oscillatoria limnetica and Aphanothece halophytica

Two facultative anoxygenic photoautotrophic cyanobacteria, Oscillatoria limnetica and Aphanothece halophytica were found capable of CO₂ photoassimilation using molecular hydrogen as electron donor in a photosystem I driven reaction. A. halophytica was also capable of evolving hydrogen from Na-dithionite reduced methylviologen in a light independent reaction.Abbreviations DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - DSPD Disallcylidenepropanediamine - FCCP Carbonylcyanide p-trifluoromethoxyphenyl hydrazone - Tricine N-tris(hydroxy methyl)-methylglycine     

Combination and positional distribution of fatty acids in lipids from blue-green algae

The main glycerolipids (monogalactosyl-, digalactosyl-, sulphoquinovosyl diacylglycerol, phosphatidylglycerol) from five blue-green algae (Microcystis, Anabaena, Nostoc, Oscillatoria, Tolypothrix) were analyzed for fatty acid composition, occurrence of diglyceride species and positional distribution of fatty acids between thesn-1- andsn-2-position of glycerol. In contrast to eucaryotic plants biosynthetically closely related lipids (monogalactosyl-, digalactosyl-, trigalactosyl diacylglycerol) show nearly identical diglyceride moieties, whereas sulphoquinovosyl diacylglycerol and phosphatidylglycerol are separated from galactolipids by composition as well as occurrence of fatty acids. On the other hand the positional distribution of fatty acids in all lipids is controlled exclusively by chain length and not by degree of unsaturation with C₁₈-fatty acids at thesn-1- and C₁₆-fatty acids at thesn-2-position. These results show that in procaryotic organisms the diversity in diglyceride portions of lipids is reduced as compared to eucaryotic organisms, but nevertheless does exist.Abbreviations MGD, DGD, TGD, SQD monogalactosyl-, digalactosyl-, trigalactosyl-, sulphoquinovosyl diacylglycerol - PG phosphatidyl glycerol     

The role of modelling in the control of toxic blue-green algae

Blooms and scums of blue-green algae (cyanobacteria)have occurred throughout the world for many years andare only one of many problems associated withover-enrichment by nutrients of fresh and marinewaters. Although much studied and written about,eutrophication poses complex and difficult managementproblems. The role of modelling as an aid to thecontrol of blue green algae is discussed.     

The effect of Daphnia on filament length of blue-green algae

Water from a hypertrophic lake rich in filamentous blue-green algae was passed through a continuous-flow system of aquaria containing Daphnia magna, and a control system without Daphnia. Daphnia caused a significant decrease in the blue-green algal density, and a two-fold reduction in filament length. It is suggested that feeding activity of Daphnia may result in an increase in the availability of blue-green filaments to filter-feeding cladocerans.     

Consequences of iron deficiency on photosynthetic and respiratory electron transport in blue-green algae

Growth of Aphanocapsa in low iron media resulted in a decrease of the endogenous iron pool. Below a critical concentration photosynthetic electron transfer was specifically depressed. This was caused by a strong inhibition of the synthesis of cytochromes b-559 of PSII, cytochromes b-563, f-557, and the Rieske Fe-S center of the cytochrome complex and especially the Fe-S centers of PSI. The influence of iron limitation on respiration and chlorphyll formation was negligible.Paper presented at the FESPP meeting (Strasbourg, 1984)     

Cyanobacteria dynamics in a restored Finnish lake: a long term simulation study

Several explanations have been presented for the formation of lacustrine cyanobacteria blooms. These include elevated water temperature, nutrient enrichment, low N/P ratios, low light energy requirements, high pH and/or low carbon dioxide concentration, selective zooplankton grazing, excretion of compounds which suppress the growth of competing algae, and migration. The impact of the first four were studied in Lake Tuusulanjärvi, a eutrophic Finnish lake, using deterministic simulation. The study, which covered 15 years, included a sequence of cases on the recovery of the lake after the implementation of two restoration measures: aeration of the hypolimnion, and termination of municipal waste discharge, both of which were done during the study period. The focus was on Microcystis and Oscillatoria, and on the N-fixing cyanobacteria, Anabaena and Aphanizomenon. Eukaryotic phytoplankton were also included in the study. Monitoring data were used. The roles of the hypotheses were discussed, from the point of view of the utility of the information in water resources management.     

Isolation and characterization of rapidly-growing,marine, nitrogen-fixing strains of blue-green algae

Five strains of heterocystous blue-green algae capable of high rates of growth and nitrogenase activity were isolated from shallow coastal environments. Growth of the organisms was characterized with respect to temperature, NaCl concentration in the medium, and nitrogen source. The temperature optima ranged from 35–42°C, and all but one of the strains displayed a requirement for added NaCl. The generation times under N₂-fixing conditions were 5.1–5.9 h, and were as low as 3.4 h for growth on NH₄Cl. Nitrogenase activity (C₂H₂ reduction) was high throughout the logarithmic growth phase of each strain. The maximum value observed for one strain was 65.5 nmoles C₂H₄ produced/mg protein x min, and the average values for the five strains ranged from 24.5–46.7 nmoles C₂H₄/mg protein x min. The organisms all belong to the genusAnabaena. The growth and nitrogenase activity of these strains are much higher than those of the heterocystous blue-green algae commonly used for investigation of nitrogen metabolism, and they thus should prove to be useful physiological tools. Their prevalence, as judged by the ease of their enrichment and isolation, in bay and estuarine environments suggests that they are important contributors of combined nitrogen.     

Nitrate and nitrite as ‘in vivo’ quenchers of chlorophyll fluorescence in blue-green algae

The effect of nitrate and nitrite on long-term chlorophyll fluorescence has been studied in filamentous blue-green algae. Cells grown autotrophically with nitrate as nitrogen source show, under argon atmosphere, a high level of fluorescence. The addition of either nitrete or nitrite induces a significant fluorescence quenching, but, whereas in the case of nitrite no previous treatment is required, in the case of nitrate the cells have to be sonicated or treated with Triton X-100 in advance without destroying their cellular integrity. DCMU strongly inhibits the quenching of fluorescence caused by nitrate or nitrite. Using cells grown with ammonia, a nutritional repressor of the two enzymes of the nitrate-reducing system, the fluorescence quenching observed in either case becomes negligible. These results clearly indicate that both nitrate and nitrite can physiologically act as primary Hill reagents in photosynthesis in blue-green algae.

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Résumé L'effect du nitrate et du nitrite sur la fluorescence de la chlorophylle a été étudié chez quelques algues bleues filameneuses. Les cellules alimentées avec du nitrate montrent, sous argon, un haut niveau de fluorescence. L'addition de quantités égales de nitrate et de nitrite induit une diminution significative de la fluorescence, mais si, dans le cas du nitrite, un traitement préalable n'est pas nécessaire, dans le cas du nitrace, les cellules doivent être traitées légèrement aux ultra sons ou avec du Triton X-100, sans détruire leur intégrité cellulaire. Le DCMU inhibe sévèrement la diminution de fluorescence causée par le nitrate ou le nitrite. Dans les cellules alimentées avec l'ammoniaque, un répresseur des deux enzymes du système de réduction du nitrate, la diminution de fluorescence devient negligeable quel que soit le composé employé. Enfin, ces résultats montrent clairement que tant le nitrate que le nitrite peuvent être des réactifs primaires et physiologiques de la réaction de Hill dans la photosynthèse de nitrate en algues bleues.

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Metal concentrations in Sargassum algae from coastal waters of Nha Trang Bay (South China Sea)

The concentrations of metals, viz., Fe, Mn, Cu, Zn, Cd, Pb, and Ni, were investigated in brown algae of the genus Sargassum collected in the coastal waters of Nha Trang Bay (South China Sea). Metal concentrations in algae growing in the zone of influence of the city of Nha Trang were higher than those in macrophytes collected to the south and north of the city. Similar levels of Cu and Fe concentrations were observed in macrophytes from the urbanized coastal areas of Nha Trang Bay and in algae from the Peter the Great Bay (Sea of Japan). This is suggestive of comparable metal inputs from the anthropogenic sources of the cities of Nha Trang and Vladivostok (Peter the Great Bay). However, the concentrations of Pb, Ni, and Cd in algae from the coastal waters of Nha Trang Bay were lower than in macrophytes from the inshore zone of Vladivostok. The high level of pollution of sea water with Zn compounds near Nha Trang was local. The metal levels in macrophytes from background areas reflect the geochemical features of the environment. Sargassum algae from Nha Trang Bay had lower concentrations of Zn, Cd, and Ni and higher concentrations of Mn than algae from Peter the Great Bay. The background concentrations of Cu, Pb, and Fe in macrophytes from both bays were virtually the same.     

Chemistry and plant ecology of zinc-rich wastes dominated by blue-green algae

An account is given of the chemistry and vegetation of wet areas below the Elvins tailings pile in the Old Lead Belt of Missouri. Zinc in particular is present at highly elevated levels in the water (5.9–21.0 mg l^–1) and most sediments. The two most widespread plants are a blue-green alga,Plectonema gracillimum, and a moss,Dicranella sp. In wetter areas the latter exists predominantly as protonema.Plectonema and the protonema typically grow in very close association, although situations do occur where only one or the other is present. For instance, algal flocs in two permanent ponds consisted largely ofPlectonema and unicellular blue-green algae, with a few eukaryotic algae, but no protonema. Other dominants in the area areEleocharis sp.,Scirpus americanus andTypha latifolia. One seepage was studied in more detail; it showed marked changes in both chemistry and vegetation on passing from source to a site 15 m downstream. Aqueous Zn dropped from 21 to 8 mg l^–1. ThePlectonema-Dicranella protonema community predominated in the upper part, developing a laminated structure up to 3 cm thick (justifying recognition as a stromatolite). Further downstream a white crust including much hydrozincite and with a very high overall zinc content (c. 370 mg g^–1 Zn) was deposited over the green layer, making it endolithic in position, though probably not in origin. Still further downstream the green layer disappeared, leaving only a hard white crust. A discussion is included of the extent to which observed variations in the zinc content of water and sediments below the tailings pile are influenced by living and dead plants. An apparent diel cycle in aqueous zinc at some sites is of particular interest, as it was not matched by changes in Ca or Cd.     

Comparison of the long-wave chlorophyll fluorescence in various green and blue-green algae and diatoms

Two types of long-wave fluorescence bands with similar band shape occur at room temperature in various algae: F_II700 and F_I715. F_II700 occurs in a limited number of algae, follows PS II transients, increases with culture age and is moderately increased by cooling to 83 K. F_I715 occurs in most algae, especially Anabaena, but much less in most diatoms and Tribonema. It does not follow PS II transients, does not increase with culture age and is much increased by cooling to 83 K.An interpretation for the characteristics of F_II700 and F_I715 is given.     

Sucrose synthase is involved in the conversion of sucrose to polysaccharides in filamentous nitrogen-fixing cyanobacteria

Higher plants and cyanobacteria metabolize sucrose (Suc) by a similar set of enzymes. Suc synthase (SuS, UDP-glucose: D: -fructose 2-alpha-D: -glucosyl transferase, EC 2.4.1.13) catalyses the synthesis and cleavage of Suc, and in higher plants, it plays an important role in polysaccharides biosynthesis and carbon allocation. In this work, we have studied the functional relationship between SuS and the metabolism of polysaccharides in filamentous nitrogen-fixing cyanobacteria. We show that the nitrogen and carbon sources and light regulate the expression of the SuS encoding gene (susA), in a similar way that they regulate the accumulation of polysaccharides. Furthermore, glycogen content in an Anabaena sp. mutant strain with an insertion inactivation of susA was lower than in the wild type strain under diazotrophic conditions, while both glycogen and polysaccharides levels were higher in a mutant strain constitutively overexpressing susA. We also show that there are soluble and membrane-bound forms of SuS in Anabaena. Taken together, these results strongly suggest that SuS is involved in the Suc to polysaccharides conversion according to nutritional and environmental signals in filamentous nitrogen-fixing cyanobacteria.     

Influence of toxic and non-toxic phytoplankton on feeding and survival of Dreissena polymorpha (Pallas) larvae

Grazing and survival of larvae of the zebra mussel, Dreissena polymorpha, on a green alga and cyanobacteria were studied in laboratory experiments. Clearance rates of the larvae were determined for Chlamydomonas reinhardtii (green alga), two non-toxic and two toxic Microcystis aeruginosa strains (Cyanobacteria). Clearance rates of larvae on non-toxic Microcystis were significantly higher than on toxic Microcystis. The clearance rate on Chlamydomonas reinhardtii was in between the clearance rates on toxic and non-toxic Microcystis strains and not significantly different from them. Effects of toxicity of Microcystis on the survival of zebra mussel larvae was investigated in a short-term experiment. Survival of larvae fed toxic Microcystis was lower than that of larvae fed non-toxic Microcystis, but higher than that of starved larvae. This may imply that, for survival of zebra mussel larvae, it is better to have bad quality (toxic) food than no food.     

Genetic diversity within populations of cyanobacteria assessed by analysis of single filaments

We have developed a technique for determining the genetic structure of populations of filamentous cyanobacteria. The sequence diversity at specific gene loci is first characterised in a range of clonal cultures; subsequent analysis involves individual trichomes collected directly from natural populations. This technique has been used to examine the population genetic structure of Nodularia in the Baltic Sea and Planktothrix in Lake Zürich. For Nodularia, studies utilising four polymorphic loci reveal that even though there is a degree of linkage disequilibrium, horizontal transfer of genetic information has been sufficient to generate many of the possible allelic combinations. Analyses reveal both spatial and temporal variation in population genetic structure. Other studies of both Nodularia and Planktothrix have shown a correlation between particular alleles at the gvpC locus and the critical pressure of the gas vesicles that accumulate within the cell. We are now investigating how the natural selection of different gas vesicle phenotypes, imposed by changes in the depth of the upper mixed layer of the water column, affects the relative success of individual cyanobacteria possessing different gvpC alleles. This revised version was published online in August 2006 with corrections to the Cover Date.     

Toxicity of the blue-green alga Oscillatoria agardhii to the mosquito Aedes aegypti and the shrimp Artemia salina

The cyanobacterium Oscillatoria agardhii 27, which does not produce mammalian neuro- or hepatotoxins, was highly toxic to the larval stages of the yellow fever mosquito Aedes aegypti: its 24-h LC₅₀ values against fourth-and second-instar larvae of A. aegypti were 8.7 and 6.1 g live cells/ml, respectively. The toxin was water-soluble and was partially purified but the chemical nature of the toxic compound(s) is still unknown. Aqueous solutions were also toxic to the newborn larvae of the brine shrimp, Artemia salina, used for the bioassay. The toxic activity of these solutions decreased markedly on heating to 90°C for 15 min.J. Kiviranta is with the Department of Pharmacy, P.O. Box 15, FIN-00014 University of Helsinki, Helsinki, Finland; A. Abdel-Hameed is usually with the Department of Microbiology, Faculty of Pharmacy, Cairo University, Kasr-El-Aini Street, Cairo, Egypt, but is presently with the Department of Applied Chemistry and Microbiology, P.O. Box 27, Viikki, Building B, FIN-00014 University of Helsinki, Helsinki, Finland.     

Toxicity and biodegradation of fluometuron by selected cyanobacterial species

The Biodegradation capabilities of six selected cyanobacterial species for fluometuron, a phenylurea herbicide, as well as its inhibitory effect on chlorophyll a content were investigated. The selected species (three strains of Microcystis aeruginosa, Anabaena cylindrica, A. flos-aquae and A. spiroides) were subjected to three elevated concentrations of fluometuron (0.14, 0.7 and 1.4 mg/ml) for different exposure times (1–5 days). Results revealed that biodegradation of fluometuron is species-dependent and positively correlated with the exposure time, reaching maximum efficiency after 5 days at all the investigated concentrations. All the species tested showed generally great ability to degrade the compound even at the highest concentration with specific variations among them. Biodegradation efficiencies of fluometuron by the selected species were in the following ranges; 39.2–99.9; 87.5–100; and 93.2–100 at 0.14; 0.7 and 1.4 mg fluometuron/ml respectively. It was noticed that the gradual increase in the pesticide concentration enhances its biodegradability by the selected algal species. Variations according to species as well as exposure time were discussed. The highest fluometuron concentration (1.4 mg/l) showed the highest inhibition of chlorophyll a content in the tested species and toxicity was also species- and time-dependent.