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At least 775 records · Page 43Linked to original sources
PubMed2003

Comparison of ammonia volatilisation rates in algae and duckweed-based waste stabilisation ponds treating domestic wastewater.

Quantification of ammonia volatilisation from wastewater stabilisation ponds is important in order to understand its significance for overall nitrogen removal in these widely applied low-cost treatment systems. Ammonia volatilisation rates were measured in pilot plant facilities consisting of one line of four algae-based ponds in series and a parallel line of four ponds with a floating mat of duckweed (Lemna gibba). Ammonia volatilisation was assessed during a period of one and a half years. The method applied is accurate, convenient and is proposed for analysis of a wide range of gasses emitted from stabilisation ponds and possibly other aquatic systems. The ammonia volatilisation rates in algae-based ponds (ABPs) were higher than in duckweed-based ponds (DBPs). This can be explained by the lower values of NH(3) in DBPs due to shading and lower pH values, since the volatilisation rate highly correlated with free ammonia concentration (NH(3)) in pond water. The duckweed cover appeared not to provide a physical barrier for volatilisation of unionised ammonia, because whenever NH(3) concentrations were equal in ABP and DBP also the volatilisation rates were equal. Volatilisation was in the range of 7.2-37.4 mg-Nm(-2)d(-1) and 6.4 -31.5 mg-Nm(-2)d(-1) in the ABPs and DBPs, respectively. Average influent and effluent ammonium nitrogen measurements showed that the ammonia volatilisation during the study period in any system did not exceed 1.5% of total ammonium nitrogen removal. Therefore this study confirmed results from simultaneous experimental work in our laboratory indicating that nitrification/denitrification, rather than ammonia volatilisation, is the most important mechanism for N removal in ABPs and DBPs.

Ammonia↗
PubMedDate not supplied

Bioavailability of wastewater-derived organic nitrogen to the alga Selenastrum Capricornutum.

Recent attempts to control cultural eutrophication in nitrogen-limited systems have focused on the simultaneous control of all forms of nitrogen with the underlying assumption that inorganic and organic nitrogen are equally bioavailable. To assess the validity of this assumption, algal growth bioassays were conducted on denitrified wastewater effluent samples, in the presence and absence of bacteria isolated from an effluent-receiving surface water. Bioassay results indicated that wastewater-derived dissolved organic nitrogen (DON) is not bioavailable to the algae Selenastrum Capricornutum in the absence of bacteria. However, approximately half of the wastewater-derived organic nitrogen was available to the algae in the presence of bacteria during a 2-week incubation. These results suggest that while it is inappropriate to assume that wastewater-derived DON cannot cause cultural eutrophication, it will not cause as much eutrophication as inorganic nitrogen. Additional research is needed to develop methods of minimizing the discharge of bioavailable forms of wastewater-derived organic nitrogen by wastewater treatment plants.

Biological Assay↗
PubMed2005

Ozonation of the marine dinoflagellate alga Amphidinium sp.--implications for ballast water disinfection.

Ozone has been investigated for its potential to remove marine dinoflagellate algae from ships' ballast water. Dinoflagellate algae, Amphidinium sp. isolated from the Great Barrier Reef, Townsville, Australia were used as indicators since these produce a type of cyst that is difficult to inactivate, but are relatively easy to culture. The ozonation experiments have demonstrated a high ozone demand for inactivation of the algal cultures, which increases as the culture ages. The main ozone demand in seawater is due to its reaction with bromide to form bromine compounds. The non-bromide ozone demand has been estimated by measuring the residuals produced after various doses of ozone. The Amphidinium sp. show an unexpected response to both ozonation and bromination, with an instantaneous inactivation of the organisms for all doses that produced an oxidant residual in the seawater, followed by an effect of the disinfection residual. The standard design procedure of comparing Ct will not be effective for predicting the response of the organism to varying dose, C, and contact time, t, and a plot of ozone produced oxidant residual against organism inactivation for various contact times is proposed for design purposes. High doses of ozone (5-11 mg/L) and up to 6h of residual contact were required for a 4-log inactivation of the Amphidinium sp. Ozonation is likely to be a difficult technology to implement for organisms with this ozone requirement in combination with characteristics of ballast tanks, which contain areas of sediments high in detritus and areas of corrosion.

Animals↗
PubMed1997

Cloning and sequencing of the gene encoding the plasma membrane H(+)-ATPase from an acidophilic red alga, Cyanidium caldarium.

A cDNA containing an open reading frame encoding the putative plasma membrane H(+)-ATPase in an acidophilic red alga, Cyanidium caldarium, was cloned and sequenced by means of PCR and Southern hybridization based on homologous sequences of P-type ATPases found in other organisms. The cloned cDNA is 3300 bp in length, containing a 2865 bp open reading frame encoding a polypeptide of 955 amino acids which has a predicted molecular mass of 105,371. The deduced amino acid sequence was found to be more homologous to those of P-type H(+)-ATPases from higher plants than that from the green alga Dunaliella bioculata.

Amino Acid Sequence↗
PubMed1999

Two light-activated conductances in the eye of the green alga Volvox carteri.

Photoreceptor currents of the multicellular green alga Volvox carteri were analyzed using a dissolver mutant. The photocurrents are restricted to the eyespot region of somatic cells. Photocurrents are detectable from intact cells and excised eyes. The rhodopsin action spectrum suggests that the currents are induced by Volvox rhodopsin. Flash-induced photocurrents are a composition of a fast Ca2+-carried current (PF) and a slower current (PS), which is carried by H+. PF is a high-intensity response that appears with a delay of less than 50 micros after flash. The stimulus-response curve of its initial rise is fit by a single exponential and parallels the rhodopsin bleaching. These two observations suggest that the responsible channel is closely connected to the rhodopsin, both forming a tight complex. At low flash energies PS is dominating. The current delay increases up to 10 ms, and the PS amplitude saturates when only a few percent of the rhodopsin is bleached. The data are in favor of a second signaling system, which includes a signal transducer mediating between rhodopsin and the channel. We present a model of how different modes of signal transduction are accomplished in this alga under different light conditions.

Biophysical Phenomena↗
PubMed1996

Sulfated galactans from Australian specimens of the red alga Phacelocarpus peperocarpos (Gigartinales, Rhodophyta).

Polysaccharides from the red alga Phacelocarpus peperocarpos were extracted with hot water, clarified, and precipitated with 2-propanol. The native preparation was highly sulfated (36.2% w/w). Alkali modification decreased the sulfate content by 2.0% w/w. The alkali-modified polysaccharide is composed mostly of galactose (Gal. 51 mol%) and 3,6-anhydrogalactose (AnGal, 41 mol%), with minor amounts of a mono-O-methylgalactose (MeGal, 1 mol%), xylose (Xyl, 6 mol%), and glucose (Glc, 1 mol%). The FTIR spectrum of the alkali-modified polysaccharide resembled kappa-carrageenan with absorption at 930 cm-1 (indicative of AnGal) and 850 cm-1 (Gal 4-sulfate). However, an additional, major band of absorption occurred sulfate ester substitution at O-6 of at 820 cm-1, indicating the presence of equatorial sulfate ester substitution at O-6 of Gal residues. A combination of linkage and 13C NMR spectroscopic analyses showed that the polysaccharide was composed predominantly of a novel repeating-unit, O-beta-D-galactopyranosyl 4,6-disulfate)-(1-->4)-3,6-anhydro-alpha-D-galactopyranose. Minor structural variations also occurred, including alternative patterns of sulfation and the presence of terminal Xylp. The location of the terminal Xylp residues was not certain but evidence supported their attachment at O-3 of some 4-linked Galp residues. The cell-wall galactans remain unchanged during the life cycle of the alga.

Australia↗
PubMed1989

Calmodulin-binding proteins are developmentally regulated in gametes and embryos of fucoid algae.

Calcium-binding proteins and calmodulin-binding proteins were identified in gametes and zygotes of the marine brown algae Fucus vesiculosus, Fucus distichus, and Pelvetia fastigiata using gel (SDS-PAGE) overlay techniques. A calcium current appears to be important during cell polarization in fucoid zygotes (K.R. Robinson and L.F. Jaffe, 1975, Science 187, 70-72; K.R. Robinson and R. Cone, 1980, Science 207, 77-78), but there are no biochemical data on calcium-binding proteins in these algae. By using a sensitive 45Ca2+ overlay method designed to detect high-affinity calcium-binding proteins, at least 9-11 polypeptides were detected in extracts of fucoid gametes and zygotes. All samples had calcium-binding proteins with apparent molecular weights of about 17 and 30 kDa. A 17-kDa calcium-binding protein was purified by calcium-dependent hydrophobic chromatography and was identified as calmodulin by immunological and enzyme activator criteria. A 125I-calmodulin overlay assay was used to identify potential targets of calmodulin action. Sperm contained one major calmodulin-binding protein of about 45 kDa. Eggs lacked major calmodulin-binding activity. A 72-kDa calmodulin-binding protein was prominent in zygotes from 1-65 hr postfertilization. Both calmodulin-binding proteins showed calcium-dependent binding activity. Overall, the data suggest that the appearance and distribution of certain calcium-binding and calmodulin-binding proteins are under developmental regulation, and may reflect the different roles of calcium during fertilization and early embryogenesis.

Autoradiography↗
PubMed2003

Changes in the LHCI aggregation state during iron repletion in the unicellular red alga Rhodella violacea.

Red algae are well suited to study the effects of iron deficiency on light-harvesting complex for photosystem I (LHCI), since they are totally devoid of light-harvesting complex for photosystem II (LHCII). Iron starvation results in a reduction of the pigment content, an increase of the fluorescence yield and a new emission band at 705 nm in the 77 K fluorescence emission spectra. These changes reflect the accumulation of uncoupled, aggregated LHCI in iron-depleted cells. Reconnection of LHCI to de novo synthesized reaction center I (RCI) is the first event, which takes place after iron addition. The changes in the aggregation state of LHCI are likely to occur also in brown and green algae.

Iron↗
PubMed1998

Cloning and expression of the gene for a vanadium-dependent bromoperoxidase from a marine macro-alga, Corallina pilulifera.

The cDNAs for a vanadium-dependent bromoperoxidase were cloned from a marine macro-alga, Corallina pilulifera. The open reading frame of one clone (bpo1) encoded a protein of 598 amino acids with a calculated molecular mass of 65312 Da in good agreement with that of 64 kDa determined for the native enzyme. The deduced amino acid sequence coincided well with partial sequences of peptide fragments of the enzyme. From the same cDNA library we also isolated another cDNA clone (bpo2) encoding a protein of 597 amino acids with an identity of about 90% to BPO1, suggesting a genetic diversity of the bromoperoxidase gene of C. pilulifera growing in a relatively narrow area. The carboxy-terminal 123 residues of the enzyme (BPO1) showed an identity of 45% to that of the marine macro-alga Ascophillum nodosum. The homology search of the sequences of bromoperoxidases from C. pilulifera (this study) and A. nodostum, and chloroperoxidase from the fungus Curvularia inaequalis indicated highly conserved sequences PxYxSGHA and LxxxxAxxRxxxGxHxxxD. Furthermore, it was found that the histidine residue directly bound to vanadium, other residues building up the metal center and catalytic histidine residue forming the active site of the chloroperoxidase from C. inaequalis are conserved in the primary structure of the bromoperoxidase from C. pilulifera. The cloned hpol was introduced into Escherichia coli, and the expressed PO1 was purified from the recombinant strain. The N-terminal amino acid sequence of the purified BPO1 was identical to the deduced sequence from the cDNA except the N-terminal methionine.

Amino Acid Sequence↗
PubMed1999

Separation and identification of hydrocarbons and other volatile compounds from cultured blue-green alga Nostoc sp. by gas chromatography-mass spectrometry using serially coupled capillary columns with consecutive nonpolar and semipolar stationary phases.

The complex hydrocarbons and volatile compounds produced by cultured blue-green alga Nostoc sp. were separated by serially coupled capillary columns with consecutive nonpolar and semipolar stationary phases. More than 130 metabolites including, cyclohexane, cyclopentane, normal saturated hydrocarbons (C7-C30), fatty acids and benzene derivatives were identified by GC-MS. The most abundant family of hydrocarbons identified were derivatives of cyclohexane (41) and cyclopentane (11). Most of these compounds have not been reported previously in blue-green algae studies.

Cyanobacteria↗
PubMed2000

Brominated anisoles and cresols in the red alga Polysiphonia sphaerocarpa.

The red marine alga Polysiphonia sphaerocarpa was extracted by a simultaneous steam distillation-solvent extraction technique and several brominated compounds were identified by gas chromatography-mass spectrometry. The compounds detected were 2,4-dibromoanisole, 2,4,6-tribromoanisole, 3-bromocresol, 3,5-dibromocresol, 3-bromo-4-hydroxybenzaldehyde, 3,5-dibromo-4-hydroxybenzaldehyde, 2-bromophenol, 4-bromophenol, 2,4-dibromophenol, 2,6-dibromophenol and 2,4,6-tribromophenol. This is the first time brominated anisoles and cresols have been detected in marine algae.

Anisoles↗
PubMed2003

The F684/F735 chlorophyll fluorescence ratio: a potential tool for rapid detection and determination of herbicide phytotoxicity in algae.

The use of herbicides constitutes the principal method of weed control but the introduction of these compounds into the aquatic environment (primarily through runoff) may have severe consequences for non-target plants. In this study, we describe a sensitive and inexpensive method for detection of photosynthesis-inhibiting herbicides, based on chlorophyll (Chl) fluorescence emission. Algae exhibited a Chl fluorescence signature with two maxima around 684 and 735 nm, correlated with the total Chl content of the algal suspension. The ratio of these two maxima (i.e. F684/F735) can be used as an indicator of stress in the photosynthetic apparatus, and thus represents a very simple method for in vivo evaluation of the health status of algae. Determination of the F684/F735 fluorescence ratio revealed the presence and phytotoxicity of atrazine, metribuzin, terbuthylazine, diuron, DCPMU, DCPU and paraquat. The toxic effect of these pollutants was estimated by monitoring the increase in the F684/F735 value, which reflects photosystem II and photosystem I photochemistry. We observed a drastic increase in the magnitude of this ratio, correlating quantitatively with herbicide concentration and corresponding to a decline in algal photosynthetic activity. For the tested herbicides affecting photosynthetic electron transport, the magnitude of the effect was as follows: diuron= DCPMU > metribuzin > atrazine > terbuthylazine > paraquat > DCPU. The F684/F735 Chl fluorescence ratio thus gives toxicity responses which compare favourably with tests such as the algal growth inhibition test, and could therefore be used to detect the presence and phytotoxicity of herbicides in aquatic environments.

Chlorophyll↗
PubMed2003

Effects of substrate concentrations on the growth of heterotrophic bacteria and algae in secondary facultative ponds.

This paper presents the effect of substrate concentration on the growth of a mixed culture of algae and heterotrophic bacteria in secondary facultative ponds (SFPs) utilizing settled domestic sewage as a sole source of organic carbon. The growth of the mixed culture was studied at the concentrations ranging between 200 and 800 mg COD/l in a series of batch chemostat reactors. From the laboratory data, the specific growth rate (micro) was determined using the modified Gompertz model. The maximum specific growth rate ( micro(max)) and half saturation coefficients (K(s)) were calculated using the Monod kinetic equation. The maximum observed growth rate ( micro(max)) for heterotrophic bacteria was 3.8 day(-1) with K(s) of 200 mg COD/l. The micro(max) for algal biomass based on suspended volatile solids was 2.7 day(-1) with K(s) of 110 mg COD/l. The micro(max) of algae based on the chlorophyll-a was 3.5 day(-1) at K(s) of 50mg COD/l. The observed specific substrate removal by heterotrophic bacteria varied between the concentrations of substrate used and the average value was 0.82 (mg COD/mg biomass). The specific substrate utilization rate in the bioreactors was direct proportional to the specific growth rate. Hence, the determined Monod kinetic parameters are useful for the definition of the operation of SFPs.

Bacteria↗
PubMed2000

Electron microscopy study of biosorbents from marine macro alga Durvillaea potatorum.

Biosorbents derived from the biomass of marine algae have shown to have high uptake capacities for heavy metals and the internal structure has been generally assumed to be pseudo-homogenous. In this paper, the microstructures of biosorbents derived from Australian marine alga Durvillaea poratorum were analysed using scanning electron microscopy. The structural components of the biosorbent resembled fiber-like cylinders. The internal structure was a highly connected network of cylinders with varying sizes. Methods of drying and pre-treatment of the biomass also affected the details of the internal structure. Calcium chloride followed by thermal treatment provided the most uniform cylinder networks for the biosorbents. Heavy metal Cu2+ and Cd2+ binding in the biomass was confirmed by using an electron probe microanalyser.

Absorption↗
PubMed2001

Biosynthesis and release of methylarsenic compounds during the growth of freshwater algae.

Arsenic transformations by freshwater algae have been studied under laboratory conditions. By the use of a new analytical method, we identified methylarsenic(III) species in the growth medium of green-alga Closterium aciculare incubated under axenic conditions. The arsenate concentration in the experimental medium began to decrease just after inoculation, and the levels of arsenite and methylarsenicals increased with the growth of C. aciculare. Initially, most of the arsenate was converted into arsenite, which peaked in concentration during the exponential phase. Methylarsenicals accumulated rapidly in the stationary phase. DMAA(V) production was enhanced when the ratio of phosphate to arsenate decreased in the culture medium. The levels of DMAA(V) increased continuously toward the end of the experiment. On the other hand, methylarsenic(III) species remained relatively steady during the stationary phase. Methylarsenic(III) species accounted for 0-35% of methylarsenicals. These results suggest that arsenite and methylarsenicals (containing methylarsenic(III) species) are supplied by phytoplankton, and serve as evidence of the origin of methylarsenic(III) species in natural waters.

Arsenates↗
PubMed2002

Biosorption of copper(II) from aqueous solutions by pre-treated biomass of marine algae Padina sp.

Biosorption of heavy metals can be an effective process for the removal and recovery of heavy metal ions from aqueous solutions. The biomass of marine algae has been reported to have high uptake capacities for a number of heavy metal ions. In this paper, the adsorption properties of a pre-treated biomass of marine algae Padina sp. for copper(II) were investigated. Equilibrium isotherms and kinetics were obtained from batch adsorption experiments. The biosorption capacities were solution pH dependent and the maximum capacity obtained was 0.80 mmol/g at a solution pH of about 5. The biosorption kinetics was found to be fast, with 90% of adsorption within 15 min and equilibrium reached at 30 min. The effects of light metal ions on copper(II) uptake were studied and the presence of light metal ions did not affect copper(II) uptake significantly. Fixed-bed breakthrough curves for copper(II) removal were also obtained. This study demonstrated that the pre-treated biomass of Padina sp. could be used as an effective biosorbent for the treatment of copper(II) containing wastewater streams.

Adsorption↗
PubMed1997

Mussels and algae as bioindicators for long-term tendencies of element pollution in marine ecosystems.

Results of more than ten years of experience in the determination of metals in mussels and algae collected in the North Sea and the Baltic Sea are presented. The various elements determined here are Hg, As, Se, Cd, Pb, Cu, Na, K, S, P, Zn, Mn, Fe, Sr, Ca, Ba, Mg, Tl, Ni, Co using techniques such as cold vapor AAS, INAA, hydride generation AAS, electrothermal AAS, ICP-AES, IDMS and stripping voltammetry. The results indicate the occurrence of three groups of elements with respect to long-term tendencies of their concentrations. In the first group, the concentrations in both mussels and algae varied in the same manner; in the second group no change was observed in either matrix while in the third group, the concentrations of elements changed in an opposite manner.

Animals↗
PubMed1999

Studies on nitric oxide (NO) formation by the green alga Scenedesmus obliquus and the diazotrophic cyanobacterium Anabaena doliolum.

This study provides preliminary evidence that NO production could be a general attribute of algae. Anabaena doliolum was found to be a better NO producer than Scenedesmus and Synechoccocus. Experiments conducted with inhibitors of photosynthesis (DCMU), ATP synthesis (DCCD), and the uncoupler (2,4-DNP) and its analog arsenate clearly revealed that inhibition of nitrite assimilation through the blockage of nitrite reductase (NiR) is primarily responsible for NO emission. A linear relationship between nitrite concentration in the culture medium and NO in the exhaust gas supports the view that accumulation of nitrite is responsible for NO formation. A failure of Scenedesmus, grown in the medium substituted with W for Mo, to produce either NO/NO-2 in light or a 'light-off' peak, and a resumption of these activities upon the addition of Mo proved beyond doubt that a functional nitrate reductase (NR) is necessary for the production of nitrite and NO by algae grown on nitrate as the nitrogen source. Moreover, the appearance of a NO peak immediately after nitrite supplementation under dark conditions in W-substituted cultures with or without glucose ruled out an enzymatic role of NR in NO emission.

2,4-Dinitrophenol↗