Polyphosphate metabolism in the blue-green alga Microcystis aeru-ginosa

The uptake of inorganic phosphorus was studied in an axenicstrain of phosphorus-starved cells of the blue-green alga Microcystisaeruginosa, an organism often causing blooms in freshwater bodies.Rates of growth and of cellular polyphosphate content as a functionof initial orthophosphate in the medium indicate the operationof the ‘phosphorus overplus’ phenomenon in M. aeruginosa,accompanied by formation of volutin granules. The granules wereisolated by a non-aqueous centrifugation method, and identifiedas polyphosphate bodies.     

Respiration of blue-green algae in the light

The CO₂ evolution in the light of Anabaena as well as several other blue-green algae is below 10% of the dark control. Addition of DCMU restores CO₂ evolution in the light almost to the dark level. Furthermore, by adding unlabeled NaHCO₃, a ¹⁴CO₂ release is observed with prelabeled algal cells attaining 15 to 100% of dark control. Analysis by double-reciprocal plots exhibits a competitive relationship between added and endogenously released carbon dioxide. We conclude that CO₂ evolved by respiration is immediately refixed in the light without being liberated.The degree of ¹⁴CO₂ release induced by unlabeled bicarbonate in the light allows to determine true photoinhibition of respiration. Anabaena variabilis Kütz. exhibits almost no inhibition while in eight other species respiration is light-inhibited between 50 and 85% of the dark control.Abbreviations CCCP carbonyl cyanide m-chlorophenylhydrazone - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - TCA trichloroacetic acid     

Decomposition of Blue-Green Algal (Cyanobacterial) Blooms in Lake Mendota, Wisconsin

Decomposition of natural populations of Lake Mendota phytoplankton dominated by blue-green algae (cyanobacteria) was monitored by using oxygen uptake and disappearance of chlorophyll, algal volume (fluorescence microscopy), particulate protein, particulate organic carbon, and photosynthetic ability (¹⁴CO₂ up-take). In some experiments, decomposition of ¹⁴C-labeled axenic cultures of Anabaena sp. was also measured. In addition to decomposition, mineralization of inorganic nitrogen and phosphorus were followed in some experiments. Decomposition could be described as a first-order process, and the rate of decomposition was similar to that found by others using pure cultures of eucaryotic algae. Nitrogen and phosphorus never limited the decomposition process, even when the lake water was severely limited in soluble forms of these nutrients. This suggests that the bacteria responsible for decomposition can obtain all of their key nutrients for growth from the blue-green algal cells. Filtration of lake water through plankton netting that removed up to 90% of the algal biomass usually did not cause a similar decrease in oxygen demand, suggesting that most of the particulate organic matter used for respiration of the decomposing bacteria was in a small-particle fraction. Short-term oxygen demand correlated well with the particulate chlorophyll concentration of the sample, and a relationship was derived that could be used to predict community respiration of the lake from chlorophyll concentration. Kinetic analysis showed that not all analyzed components disappeared at the same rate during the decomposition process. The relative rates of decrease of the measured parameters were as follows: photosynthetic ability > algal volume > particulate chlorophyll > particulate protein. Decomposition of ¹⁴C-labeled Anabaena occurred at similar rates with aerobic epilimnetic water and with anaerobic sediment, but was considerably slower with anaerobic hypolimnetic water. Of the various genera present in the lake, Aphanizomenon and Anabaena were more sensitive to decomposition than was Microcystis. In addition to providing a general picture of the decomposition process, the present work relates to other work on sedimentation to provide a detailed picture of the fate of blue-green algal biomass in a eutrophic lake ecosystem.     

Struttura e biomassa dei popolamenti fitoplanctonici del Lago Omodeo (Sardegna centrale)

Abstract

Composition and biomass of phytoplanktonic communities of Lago Omodeo (Central Sardinia).—A qualitative and quantitative study has been made on the phytoplankton of Lago Omodeo. The algal associations are typical of eutrophic waters. The dominant blue-green algae in summer and autumn were: Chroococcus dispersus, Microcystis flos-aquae, Aphanizomenon flos-aquae, Anabaena flos-aquae, Anabaena planctonica; dominant in winter and spring the diatom Melosira distans. The mean standing crop of algae for the trophogenic zone was 9.2 mm³/l; a maximum crop of 53 mm³/l was recorded in August during a Microcystis bloom.     

Deposition of condensed phosphate as an effect of varying sulfur deficiency in the cyanobacterium Synechococcus sp. (Anacystis nidulans)

Uptake of orthophosphate and deposition of condensed phosphate were investigated in cells of Synechococcus sp. (Anacystis nidulans) deficient in phosphorus or sulfur. When phosphorus was restored to phosphorus-starved cells, uptake was rapid and immediate, with the greatest accumulation occurring within the first hour. Uptake was optimum in the pH 7.5–8.5 range. Long-term (6-day) studies of uptake and deposition with cells exposed to a wide range of sulfur deficiency showed that both processes were greatest when the level of exogenous sulfur was reduced to zero. The increase in cellular phosphorus as determined chemically was in agreement with the increased number and size of polyphosphate bodies at the ultrastructural level. Possible mechanisms for the control of phosphorus uptake and condensed phosphate formation by exogenous sulfur are discussed.     

An experimental demonstration of trophic interactions affecting water quality of Rice Lake, Ontario (Canada)

Eight cylindrical enclosures (3 m diameter, 2.7 m long, V = 20m³) were installed in eutrophic Rice Lake (Ontario, Canada) in late spring of 1987. Fish (yearling yellow perch (Perca flavescens) and macrophytes (Potamogeton crispus) presence and absence were set at the beginning of the experiment to yield four combinations of duplicate treatments. The purpose of the experiment was to determine if the phytoplankton, zooplankton, macrophytes and fish species resident in the lake interact to influence water quality (major ions, phosphorus, algal densities and water clarity).The presence of fish was associated with: (1) decreased biomass of total zooplankton, (2) decreased number of species in the zooplankton, (3) decreased average size of several zooplankton taxa, (4) higher total phosphorus concentrations, (5) higher phytoplankton and chlorophyll a concentrations, (6) lower water clarity, (7) lower potassium levels during macrophyte die-back, (8) lower pH and higher conductivity in the presence of macrophytes. Biomass of large Daphnia species (but not total zooplankton) was highly correlated with the algal response (r ² = 0.995) and was associated with reduced biomass of several algal taxa including some large forms (Mougeotia, Oedogonium) and several colonial blue-green algae. However, no significant control of late summer growth of the bloom-forming blue-green alga Anabaena planctonica Brun. was achieved by the Daphnia presence-fish absence treatment. Release of phosphorus to the water column during the die-back of P. crispus was not an important phenomenon.     

The role of nitrogen as a growth limiting factor in the eutrophic Lake Vesijärvi,southern Finland

The significance of nitrogen for algal growth was studied in Lake Vesijärvi in 1979 and 1980 by algal bioassay, using Selenastrum capricornutum and Anabaena cylindrica as test organisms. Nitrogen limited the growth of Selenastrum for the major part of the investigation period, while phosphorus seemed to be the most limiting factor for Anabaena. This difference was reflected in the in situ succession of phytoplankton. As the ratio of inorganic nitrogen to phosphate phosphorus became smaller, nitrogen-fixing blue-green algae became dominant. Nitrogen fixation was greatest at the beginning of July, coinciding with maximum heterocyst numbers.     

Water chemistry and algal vegetation of streams in the Asir Mountains,Saudi Arabia

Surveys of water chemistry and algal vegetation at nine stream sites in the Asir Mountains, Saudi Arabia, were made in March, 1984. The waters were moderately to highly calcareous with a relatively high Mg: Ca ratio and high concentrations of reactive-Si (x = 12.2 mg l^–1) and F (x = 0.73 mg l^–1). Ammonia typically constituted about one-sixth of the inorganic nitrogen. Filamentous algae (Cladophora and/or Spirogyra) were abundant at all but one site. However two sites, Wadi Habaqah and Al Tanoumah, differed considerably from the others in their overall floristic composition, with various species of Rivulariaceae, Nostoc verrucosum, Schizothrix lardacea and certain other blue-green algae present only here. With one minor exception, heterocystous blue-green algae were absent at the other sites. Tufa was deposited at these two sites, but not elsewhere. Species which appeared to play an active role in calcification included Dichothrix gypsophila, Calothrix parietina, Cladophora glomerata and the moss Bryum sp. A community apparently not previously recorded in the literature was abundant at Wadi Habaqah. This consisted of thick mats of Cladophora glomerata, with a thin surface layer of Zygnemales and numerous colonies of Nostoc verrucosum inside, or towards the underside, of the mat.     

Seasonal succession of the phytoplankton in the upper Mississippi River

Species composition and seasonal succession of the phytoplankton were investigated on the upper Mississippi River at Prairie Island, Minnesota, U.S.A. Both the numbers and volume of individual species were enumerated based on cell counts with an inverted microscope. A succession similar to algal succession in the local lakes occurred. The diatoms were dominant during the spring and fall and blue-green algae were dominant during the summer. The algal concentrations have increased up to 40 fold the concentrations of the 1920's, since the installation of locks and dams. The maximum freshweight standing crop was 4 mg · l^–1 in 1928 (Reinhard 1931), 13 mg · l^–1 in 1975 a wet year, and 47 mg · l^–1 in 1976, a relatively dry year with minimal current discharge. The diatoms varied from 36–99%, the blue-green algae from 0–44% and the cryptómonads from 0–50% of the total standing crop. The green algae were always present but never above 21% of the biomass. The dominant diatoms in recent years were centric -Stephanodiscus andCyclotella spp. (maximum 50,000 ml^–1). The dominant blue-green algae wereAphanizomenon flos-aquae (L.) Ralfsex Born.et Flahault andOscillatoria agardhii Gomont (maximum 800 ml^–1). These algal species are also present in local lakes. Shannon diversity values indicated greatest diversity of algae during the summer months.     

Phosphate uptake and utilization by bacteria and algae

Bacterial uptake of inorganic phosphate (closely investigated in Escherichia coli) is maintained by two different uptake systems. One (Pst system) is P_i-repressible and used in situations of phosphorus deficiency. The other system (Pit system) is constitutive. The Pit system also takes part in the phosphate exchange process where orthophosphate is continuously exchanged between the cell and the surrounding medium.Algal uptake mechanisms are less known. The uptake capacity increases during starvation but no clearly defined transport systems have been described. Uptake capacity seems to be regulated by internal phosphorus pools, e.g., polyphosphates. In mixed algal and bacterial populations, bacteria generally seem to be more efficient in utilizing low phosphate concentrations. The second half of this paper discusses how bacteria and algae can share limiting amounts of phosphate provided that the bacteria have pronouncedly higher affinity for phosphate. Part of the solution to this problem may be that bacteria are energy-limited rather than phosphate-limited and dependent on algal organic exudates for their energy supply.The possible phosphate exchange mechanism so convincingly demonstrated in Escherichia coli is here suggested to play a key role for the flux of phosphorus between bacteria and algae. Such a mechanism can also be used to explain the rapid phosphate exchange between the particulate and the dissolved phase which always occurs in short-term ³²P-uptake experiments in lake waters.     

31P-NMR STUDIES ON INORGANIC POLYPHOSPHATES IN MICROALGAE1

Using “P nuclear magnetic resonance analysis, total inorganic polyphosphate in algae could be quantitatively estimated, For this purpose the algal suspension, which had been kept in cold trichloroacetic acid, was further treated with 6 mM EDTA, or the cells were kept in 2 N KOH containing 100 mM EDTA for 18 h at 37°C. These simple methods avoid hydrolysis of cellular inorganic polyphosphate and, therefore, are useful for the study of phosphorus metabolism in algae. The effects of these treatments on visualization of the signal for inorganic polyphosphate in nuclear magnetic resonance spectra were discussed in comparison with in vivo, ‘P nuclear magnetic resonance spectra of algae.     

A light and electron microscopic study of the blue-green algae living either in the coralloid roots of « Macrozamia communis » or isolated in culture

Abstract

The present work is a study of the blue-green algae living in the coralloid roots of Macrozamia communis and isolated from Macrozamia communis in culture.

The light and electron microscopic study pointed out the distribution of these microorganisms in the cortical area of coralloids and did not reveal any cells invaded by bacteria. On the basis of their aspect the blue-green algae living either in the coralloid roots or in culture were classified as belonging to the genus Nosloc, with some features of Nosloc commune.

Inside the coralloids the cells of the blue-green algae were surrounded by abundant mucilage and contain granulations. In culture the blue-green algae were on the contrary very poor in mucilage and rich in polyphosphate granules. Numerous phycobilosomes were ranged along the outside of the thylakoid membranes in alternate arrangement to the granules of the neighbouring lamellae.     

Efficiency of using green algae as biological controllers against toxic algal taxa in cultured Nile tilapia Oreochromis niloticus,based on histopathological examinations

The incidence of harmful cyanobacterial blooms in surface waters has increased in frequency and outbreaks have become more severe. This research aimed at studying the effect of a culture of two green algal species as biological control of the growth of toxic blue-green algae. Nile tilapia of an initial mean weight of 55 g fish^?1 (SE 5) were used for each of four treatments in triplicate. All algal seedings were done at 4 × 10³ cells ml^?1. Treatment I (untreated) served as a control, Treatment II was seeded with Microcystis aeruginosa, Treatment III was seeded with green algae Chlorella ellipsoidea and Scenedesmus bijuga, and Treatment IV was seeded with a mixture of M. aeruginosa and C. ellipsoidea and S. bijuga. After 10 days, Treatment IV showed 3.4% viable cell survival, compared to 35% and 55% in Treatments II and III, respectively. Histopathological examination revealed mild degenerative changes and focal necrosis, as well as a depletion of haematopoietic tissues in Treatment IV compared to Treatment II. These findings suggest the efficacy of C. ellipsoidea and S. bijuga in controlling the growth of M. aeruginosa and minimising its side effects on cultured Nile tilapia.     

Effect of larval fish and nutrient enrichment on plankton dynamics in experimental ponds

The hypotheses that larval fish density may potentially affect phytoplankton abundance through regulating zooplankton community structure, and that fish effect may also depend on nutrient levels were tested experimentally in ponds with three densities of larval walleye, Stizostedion vitreum (0, 25, and 50 fish m^–3), and two fertilizer types (inorganic vs organic fertilizer). A significant negative relationship between larval fish density and large zooplankton abundance was observed despite fertilizer types. Larval walleye significantly reduced the abundances of Daphnia, Bosmina, and Diaptomus but enhanced the abundance of various rotifer species (Brachionus, Polyarthra, and Keratella). When fish predation was excluded, Daphnia became dominant, but Daphnia grazing did not significantly suppress blue-green algae. Clearly, larval fish can be an important regulator for zooplankton community. Algal composition and abundance were affected more by fertilizer type than by fish density. Inorganic fertilizer with a high N:P ratio (20:1) enhanced blue-green algal blooms, while organic fertilizer with a lower N:P ratio (10:1) suppressed the abundance of blue-green algae. This result may be attributed to the high density of blue-green algae at the beginning of the experiment and the fertilizer type. Our data suggest that continuous release of nutrients from suspended organic fertilizer at a low rate may discourage the development of blue-green algae. Nutrient inputs at a low N:P ratio do not necessarily result in the dominance of blue-green algae.     

Influence of the initial composition of algal-bacterial microcosms on the degradation of salicylate in a fed-batch culture

The influence of the initial composition of an algal-bacterial microcosm constituted of Chlorella sorokiniana and Ralstonia basilensis was tested for the fed-batch degradation of salicylate at 5 mM. Salicylate degradation was always limited by the O₂ generation rate, which was initially proportional to the algal density, but rapidly became limited by the availability of light once the algae started to grow. The decrease of the salicylate removal rate observed at high algal densities was likely caused by mutual shading within the algal population and the increase of O₂ consumption due to algal dark respiration. With repeated salicylate amendments, all systems converged towards the same characteristics, reaching an optimum rate of salicylate degradation at 1 mmol l^–1 day.     

THE UPTAKE AND OXIDATION OF GLYCOLIC ACID BY BLUE-GREEN ALGAE1

Two species of blue-green algae Anabaena flosaquae and Oscillatoria sp. were shown to assimilate glycolic acid. In the presence of DCMU in light, approximately 50% of it wax oxidized to carbon dioxide; 90% was oxidized in the dark. Glycolate assimilation was increased fivefold by lowering the pH of the medium from 9.0 to 5.0, and the rate of uptake increased with increasing concentration of exogenous glycolate up to a saturation concentration of 12–14 mM. α-Hydroxysulfonates markedly inhibited glycolate uptake and oxidation but iso-nicotinyl hydrazide had little effect. These results indicate that glycolate oxidation occurs in vivo, but that the glycolate pathway in these algae differs some-what from that of higher plants.     

Photosynthesis of Marine Macroalgae from Antarctica: Light and Temperature Requirements

The photosynthetic performance of macroalgae isolated in Antarctica was studied in the laboratory. Species investigated were the brown algae Himantothallus grandifolius, Desmarestia anceps, Ascoseira mirabilis, the red algae Palmaria decipiens, Iridaea cordata, Gigartina skottsbergii, and the green algae Enteromorpha bulbosa, Acrosiphonia arcta, Ulothrix subflaccida and U. implexa. Unialgal cultures of the brown and red algae were maintained at 0°C, the green algae were cultivated at 10°C. I_K values were between 18 and 53 μmol m^?2 s^?1 characteristic or low light adapted algae. Only the two Ulothrix species showed higher I_K values between 70 and 74 μmol m^?2 s^?1. Photosynthesis compensated dark respiration at very low photon fluence rates between 1.6 and 10.6 μmol m^?2 s^?1. Values of α were high: between 0.4 and 1.1 μmol O₂ g^?1 FW h^?1 (μmol m^?2 s^?1)^?1 in the brown and red algae and between 2.1 and 4.9 μmol O₂ g^?1 FW h^?1 (μmol m^?2 s^?1)^?1 in the green algal species. At 0°C P_max values of the brown and red algae ranged from 6.8 to 19.1 μmol O₂ g^?1 FW h^?1 and were similarly high or higher than those of comparable Arctic-cold temperate species. Optimum temperatures for photosynthesis were 5 to 10°C in A. mirabilis, 10°C in H. grandifolius, 15°C in G. skottsbergii and 20°C or higher in D. anceps and I. cordata. P: R ratios strongly decreased in most brown and red algae with increasing temperatures due to different Q₁₀ values for photosynthesis (1.4 to 2.5) and dark respiration (2.5 to 4.1). These features indicate considerable physiological adaptation to the prevailing low light conditions and temperatures of Antarctic waters. In this respect the lower depth distribution limits and the northern distribution boundaries of these species partly depend on the physiological properties described here.     

Control of phosphorus loading and flushing as restoration methods for Lake Veluwe,The Netherlands

As a result of high nutrient loading Lake Veluwe suffered from an almost permanent bloom of the blue-green algaOscillatoria agardhii Gomont. In 1979, the phosphorus loading of the lake was reduced from approx. 3 to 1 g P.m^–2.a^–1. Moreover, since then the lake has been flushed during winter periods with water low in phosphorus. This measure aimed primarily at interrupting the continuous algal bloom. The results of these measures show a sharp decline of total-phosphorus values from 0.40–0.60 mg P.l^–1 (before 1980) to 0.10–0.20 mg P.l^–1 (after 1980). Summer values for chlorophylla dropped from 200–400 mg.m^–3 to 50–150 mg.m^–3.The increase in transparency of the lake water was relatively small, from summer values of 15–25 cm before the implementation of the measures to 25–45 cm afterwards. The disappointing transparency values may be explained by the decreasing chlorophylla and phosphorus content of the algae per unit biovolume. Blue-green algae are gradually loosing ground. In the summer of 1985 green algae and diatoms dominated the phytoplankton for the first time since almost 20 years. To achieve the ultimate water quality objectives (transparency values of more than 100 cm in summer), the phosphorus loading has to be reduced further.     

A quantitative study of calcareous stream and Tintenstriche algae from the Malham district,Northern England

The algal floras of two limestone streams and two calcareous Tintenstrichen are described and compared. The most important factor governing the distribution and abundance of species was the availability of water. Permanently wet stands, dominated by filamentous blue-green algae (Schizothrix calcicola and Phormidium incrustatum) had a greater species diversity than stands subject to frequent drying which were dominated by coccoid blue-green algae (Gloeocapsa spp.).

Significant correlations were found between S. calcicola and water pH (+ve), total species numbers and pH (+ve), filamentous blue-green algae and aufwuchs thickness (+ve) and Calothrix numbers and rock mass colonized (+ve).

The algal flora of the Tintenstrichen and the streams differed, although both developed upon the same limestone formation. The results are discussed with reference to previous work, substratum stability, aufwuchs structure, water chemistry, light and temperature.     

Differences in the susceptibility to light stress in two lichens forming a phycosymbiodeme,one partner possessing and one lacking the xanthophyll cycle

Summary The effect of high light levels on the two partners of a Pseudocyphellaria phycosymbiodeme (Pseudocyphellaria rufovirescens, with a green phycobiont, and P. murrayi with a blue-green phycobiont), which naturally occurs in deep shade, was examined and found to differ between the partners. Green algae can rapidly accumulate zeaxanthin, which we suggest is involved in photoprotection, through the xanthophyll cycle. Blue-green algae lack this cycle, and P. murrayi did not contain or form any zeaxanthin under our experimental conditions. Upon illumination, the thallus lobes with green algae exhibited strong nonphotochemical fluorescence quenching indicative of the radiationless dissipation of excess excitation energy, whereas thallus lobes with blue-green algae did not possess this capacity. The reduction state of photosystem II was higher by approximately 30% at each PFD beyond the light-limiting range in the blue-green algal partner compared with the green algal partner. Furthermore, a 2-h exposure to high light levels resulted in large reductions in the efficiency of photosynthetic energy conversion which were rapidly reversible in the lichen with green algae, but were long-lasting in the lichen with blue-green algae. Changes in fluorescence characteristics indicated that the cause of the depression in photosynthetic energy conversion was a reversible increase in radiationless dissipation in the green algal partner and photoinhibitory damage in the blue-green algal partner. These findings represent further evidence that zeaxanthin is involved in the photoprotective dissipation of excessive excitation energy in photosynthetic membranes. The difference in the capacity for rapid zeaxanthin formation between the two partners of the Pseudocyphellaria phycosymbiodeme may be important in the habitat selection of the two species when living separate from one another.Abbreviations F _O yield of instantaneous fluorescence - F _M maximum yield of fluorescence induced by pulses of saturating light - F _V yield of variable fluorescence (F _M -F_O) induced by pulses of saturating light - PFD photon flux density (400–700 nm) - PS II photosystem II - q _NP coefficient for nonphotochemical fluorescence quenching - q _P (or 1-q _P ) coefficient for photochemical fluorescence quenching