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  • 1
    ISSN: 1573-5176
    Keywords: cyanobacteria ; blue-green algae ; biosynthesis ; growth ; gamma linolenic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The total lipid and fatty acid content ofSpirulina platensis UTEX 1928 was 7.2 and 2.2% respectively of cellular dry weight under controlled conditions supporting high growth rates. With increases in irradiance from 170 to 870 μmol photon m−2 s−1, growth rate increased, total lipid decreased, and fatty acid composition was unaffected. At 1411 μmol photon m−2 s−1, total lipid increased slightly and percent composition of the fatty acid gamma linolenic acid increased. Growth and total lipid content ofS. platensis were affected by changes in growth temperature from 25 to 38 °C. With increased growth rate, total lipid content increased. This suggests that the storage of carbon increases at temperatures supporting high growth rates. The degree of saturation increased with temperature. Although the percent composition of gamma linolenic acid was higher at lower growth temperature, production was still primarily a function of growth rate. The effect of temperature on fatty acid content and degree of saturation was of secondary importance. Nitrogen starvation increased total lipid content but decreased fatty acid content as a percentage of dry weight; composition of the fatty acids was unaffected. N-starvation appeared to suspend synthesis of long chain fatty acids inS. platensis, suggesting that some other compound stores fixed carbon when nitrogen is limiting. It was concluded that fatty acid production inS. platensis is maximized by optimizing culture conditions for growth.
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  • 2
    ISSN: 1573-5176
    Keywords: herbicide ; green alga ; growth ; nutrients ; photosynthesis ; it Protosiphon botryoides ; respiration ; Thiobencarb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of the herbicide thiobencarb (Saturn) were tested on the growth and physiology of the chlorophyte Protosiphon botryoides isolated from an Egyptian paddy. Assays were conducted using 16-day batch cultures. Chlorophyll and dry weight biomass yields were significantly reduced at 2–3 mg L-1 thiobencarb, and dark respiration increased and protein decreased significantly at 3 mg L-1. Reductions in exponential specific growth rate (μ) were generally small, but in some cases significant. Thiobencarb also slightly, but significantly, reduced the 77 K fluorescence parameter Fv/Fm, an indicator of maximum photosynthetic efficiency. No consistent dose-dependent changes occurred in chlorophyll per unit dry weight, total carbohydrate or gross photosynthetic capacity. Whereas half of the added thiobencarb was recovered from control (uninoculated) medium, it was largely absent from cells and culture medium after sixteen days, indicating biodegradation by the alga or associated bacteria. P. botryoides recovered fully within sixteen days following subculture in thiobencarb-free medium. Independently varying phosphate and nitrate nine-fold had no clear effect on the sensitivity of P. botryoides to thiobencarb.
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  • 3
    ISSN: 1573-5176
    Keywords: seaweed ; Agardhiella ; carrageenan ; phosphorus ; cultivation ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gas liquid chromatography, chemical analyses, and infrared and13C-NMR spectroscopies indicated that phycocolloids extracted fromAgardhiella subulata had a dominant ι-carrageenan feature with less deviant ι-carrageenan and υ-carrageenan. The presence of methylated galactose and a small contamination by xylose were registered. Unattached plants were cultivated for 4 weeks in tanks receiving seawater enriched with 53.5 µM nitrate and 0 to 20 µM phosphate (Pi) week−1. The growth was phosphorus (P)-limited up to a tissue P content of 0.14 ± 0.03% dry weight. Maximal specific growth rate and carrageenan content were observed with enrichments of 6 µM Pi and 3 µM Pi, respectively. Hence carrageenan production was promoted in the range of 3–6 µM Pi. Further Pi enrichment was useless. This phenomenon, observed with P nutrition, is comparable to the ‘Neish effect’ in nitrogen nutrition studies.
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  • 4
    ISSN: 1573-5176
    Keywords: Porphyra columbina ; growth ; reproduction ; chemical composition ; seasonality ; Rhodophyceae ; New Zealand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in biomass and chemical composition, and the reproductive phenology ofPorphyra columbina Mont. were monitored at three sites in southern New Zealand over two growing seasons. Both temporal and spatial variations were found. Seasonal changes in biomass and chemical components were correlated with seawater nitrate concentrations and temperature. The summer decline in biomass was a result of the onset of unsuitable environmental conditions and the release of reproductive tissue. Under more suitable conditions, the decline in biomass was delayed. There was an inverse relationship between vegetative growth and reproduction. Reproductive plants first appeared in August at a time of increasing temperature, irradiance and daylength. Only larger plants which were mainly found in subsites low on the shore became reproductive. Plants sampled from high subsites had a shorter growth season, were generally smaller, had lower nitrogen and pigment content and were non-reproductive.
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  • 5
    ISSN: 1573-5176
    Keywords: Gracilaria ; strain selection ; growth ; photosynthesis ; rubisco ; agar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A strain selection procedure using Gracilaria verrucosa gametophytic sporelings was found to be an efficient tool for the improvement of Gracilaria strains. Two strains, C-2 and A-18, which were isolated and grown clonally, showed higher growth rates under high and low temperature conditions, respectively, than the local Gracilaria conferta. Growth rate, photosynthesis and chlorophyll, which were measured under different temperature and photon flux densities, demonstrated an overall advantage of the selected strains over the wild type strains of both G. verrucosa and G. conferta. Growth rates were also generally in positive correlation with the carboxylase activity of Rubisco. The G. verrucosa wild type also had a 40% higher agar content than G. conferta. The selected strains thus showed higher potential for outdoor cultivation than local wild type populations.
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  • 6
    ISSN: 1573-5176
    Keywords: fluorescence ; growth ; pigments ; phytoplankton ; population dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In applied water ecology several methods for estimating the biomass or activity of phytoplankton depend on the proportion of accessory pigments (xanthophylls) to chlorophyll a. Therefore, changes in pigmentation during growth and stationary phase were investigated in four different species (Amphidinium klebsii, Euglena gracilis, Prymnesium parvum, Cryptomonas ovata) typical representatives of the major algal groups. The ratios of the different xanthophylls to chlorophyll a depended not only on the growth phase, but also on the species. InAmphidinium andEuglena, the ratio of xanthophylls to chlorophyll rises continuously during the growth phase and declined during the stationary phase. InPrymnesium, quantitative pigmentation was found to be nearly independent of the growth phase. InCryptomonas, however, this ratio was relatively constant during growth, but increased in the stationary phase. In contrast to higher plants, in which the breakdown of chlorophylls occurs before that of the xanthophylls, in three of the species both pigment classes were reduced in parallel when the cultures were in the stationary phase. AgingCryptomonas, however, exhibited a pigment breakdown pattern similar to higher plants. The use of these findings for the widely applied biomass determination by chlorophyll fluorescence and for other pigment-based methods is discussed.
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  • 7
    ISSN: 1573-5176
    Keywords: Dunaliella salina ; Chilean strains ; culture ; growth ; carotenogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study was made of growth and carotenogenesis in eight strains of the green algaDunaliella salina collected from salt ponds at Salar de Atacama (23° 30′ S; 68° 15′ W) and Antofagasta (23° 39′ S; 70° 24′ W), Chile and kept in unialgal cultures at the Laboratorio Cultivo de Algas, University of Concepcion. The algae were grown in Erdschreiber medium supplemented with 12.5% w/v NaCl, under a continuous photon flux density of approximately 150 μmol m-2 s-1 at 25 ± 4 °C without aeration. When growth reached the stationary phase, the amount of NaCl was increased to 25%. Total carotenoid content was measured during the exponential growth phase and 20 days after the addition of salt. Strain CONC-001 (Laguna La Rinconada, Antofagasta) exhibited the highest growth rate (k = 0.32 div d-1) and the lowest total carotenoid content (7.2 and 13.7 mg l-1 at 12.5 and 25% NaCl, respectively). Strain CONC-007 (Salar de Atacama) had the lowest growth rate (k = 0.14 div d-1) and yielded the highest total carotenes per volume unit (23.1 and 35.6 mg 1-1 at 12.5 and 25% NaCl) and per cell (ca. 42 pg at 25% NaCl). Total carotenoid synthesis did not increase in strains CONC-001 and CONC-006 with the increase of salinity. These strains had the greatest increase of total carotenoid-to-chlorophyll ratio (4.5- and 9.3-fold, respectively). The seven strains from Salar de Atacama had higher total carotenoid contents than the strain from Antofagasta. Cell size also varied. Strain CONC-001 cells were smallest; strain CONC-006 had the largest cells. There was an inverse correlation between maximum cell density and mean cell size.
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  • 8
    ISSN: 1573-5176
    Keywords: integrated culture ; kelp ; salmon ; growth ; economics ; nutrient uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The technical and economical feasibility of farmingLaminaria saccharina for a food base product near a salmon sea cage farm was evaluated. Suitability of kelp for nutrient removal was also analyzed. A computer model of a conceptualized system was developed in order to make the assessments. Kelp growth was modelled as a linear function of temperature and background dissolved inorganic nitrogen concentration, and it was partially experimentally validated. Based on model simulations, aLaminaria farm containing 10,60 m ropes on each end of a salmon sea cage farm is fertilized by the salmon farm and yields annually 1600 kg of dried kelp. The payback period for the initial investment of $61 × 103 is 6 years after which an annual net profit of 20 × 103 Canadian dollars ($16.68 × 103 US) can be achieved. The net present worth of the kelp farm was positive for a rate of return up to 25%. Kelp production on multiple salmon farms or at a higher kelp density could increase the overall revenue. The kelp farm does not appreciably affect background nutrient or oxygen levels. With a few modifications in the model,Nereocystis andMacrocystis farming can be substituted and evaluated for feasibility and nutrient removal efficiency.
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  • 9
    ISSN: 1573-5176
    Keywords: Gracilaria chilensis ; growth ; nutrient pulses ; epiphyte abundance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of nutrient pulse concentration and frequency onGracilaria chilensis Bird, McLachlanet O Oliveira growth and epiphyte abundace was investigated for plants grown in an indoor culture facility. The frequency of nutrient pulses (which ranged from 1 pulse to 4 pulses per 14 days) had a strong influence on plant growth, while pulse concentration (from 72 to 143 µM as ammonium) had a lesser influence. Growth became a function of total N flux only when plants received nutrient pulses at least twice per 14 days. Both pulse frequency and pulse concentration affected the abundance of epiphytic algae found attached toGracilaria thalli, but pulse frequency was the more significant of the two factors. Their effects could be combined into the single factor, total N flux. Both reasonableG. chilensis growth and low levels of epiphytes were achieved under these conditions (20 °C, 25 µ mol photon m−2 s−1 PAR) if ammonium was pulsed at relatively high concentrations (up to 150 µM) once every 7 days into otherwise nitrogen-depleted seawater.
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  • 10
    ISSN: 1573-5176
    Keywords: Trentepohlia odorata ; Dunaliella bardawil ; light intensity ; nitrogen ; growth ; carotenogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract AxenicTrentepohlia odorata was cultured at three different NH4Cl levels (3.5 × 10−2, 3.5 × 10−3, 3.5 × 10−4 M) and three different light intensities (48, 76, 122 µmol m−2 s−1). Chloride had no effect on growth over this range of concentration. High light intensity and high NH4Cl concentration enhanced the specific growth rate. The carotenoid content increased under a combination of high light intensity and low N concentration. WhenD. bardawil was exposed to the same combination of growth conditions, there was an increase in its carotenoid content. The light saturation and the light inhibition constants (K s andK i, respectively) for growth, and the saturation constant (K m) for NH4Cl were determined. TheK s andK i values were higher inT. odorata (66.7 and〉 122 σmol m−2 s−1, respectively) than inD. bardawil (5.1 and 14.7 µmol m−2 s−1, respectively). TheK m value determined at 122 µmol m−2 s−1, however, was lower inT. odorata (0.048 µM) than inD. bardawil (0.062 µM).
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