共查询到20条相似文献,搜索用时 15 毫秒
1.
Wang Changhai Sun Yingying Xing Ronglian Sun Liqin 《Biotechnology and Bioprocess Engineering》2005,10(2):103-108
For more accurately describing the durations of the light and the dark phases of microalgal cells over the whole light-dark
cycle, and probing into the relationship between the liquid circulation time or velocity, the aeration rate and cell density,
a series of experiments was carried out in 10 cm light-path flat plate photobioreactors. The results indicated that the liquid
flow in the flat plate photobioreactor could be described by liquid dynamic equations, and a high biomass output, higher content
and productivity of arachidonic acid, 70.10 gm−2d−1, 9.62% and 510.3 mg/L, respectively, were obtained under the optimal culture conditions. 相似文献
2.
Two variants of open photobioreactors were operated at surface-to-volume ratios up to 170 m−1. The mean values for July and September obtained for photobioreactor PB-1 of 224 m2 culture area (length 28 m, inclination 1.7%, thickness of algal culture layer 6 mm), operated in Třeboň (49∘N), Czech Republic, were: net areal productivity, P
net = 23.5 and 11.1 g dry weight (DW) m−2 d−1; net photosynthetic efficiency (based on PAR – Photosynthetic Active Radiation), η = 6.48 and 5.98%. For photobioreactor PB-2 of 100 m2 culture area (length 100 m, inclination 1.6%, thickness of algal culture layer 8 mm) operated in Southern Greece (Kalamata, 37∘N) the mean values for July and October were: P
net = 32.2 and 18.1 g DW m−2 d−1, η = 5.42 and 6.07%. The growth rate of the alga was practically linear during the fed-batch cultivation regime up to high biomass densities of about 40 g DW L−1, corresponding to an areal density of 240 g DW m−2 in PB-1 and 320 g DW m−2 in PB-2. Night biomass loss (% of the daylight productivity, P
L) caused by respiration of algal cells were: 9–14% in PB-1; 6.6–10.8% in PB-2. About 70% of supplied CO2 was utilized by the algae for photosynthesis. The concentration of dissolved oxygen (DO) increased from about 12 mg L−1 at the beginning to about 35 mg L−1 at the end of the 100 m long path of suspension flow in PB-2 at noon on clear summer days. Dissipation of hydraulic energy and some parameters of turbulence in algal suspension on culture area were estimated quantitatively. 相似文献
3.
Kliphuis AM Klok AJ Martens DE Lamers PP Janssen M Wijffels RH 《Journal of applied phycology》2012,24(2):253-266
In this study, a metabolic network describing the primary metabolism of Chlamydomonas reinhardtii was constructed. By performing chemostat experiments at different growth rates, energy parameters for maintenance and biomass
formation were determined. The chemostats were run at low irradiances resulting in a high biomass yield on light of 1.25 g
mol−1. The ATP requirement for biomass formation from biopolymers (K
x
) was determined to be 109 mmol g−1 (18.9 mol mol−1) and the maintenance requirement (m
ATP) was determined to be 2.85 mmol g−1 h−1. With these energy requirements included in the metabolic network, the network accurately describes the primary metabolism
of C. reinhardtii and can be used for modeling of C. reinhardtii growth and metabolism. Simulations confirmed that cultivating microalgae at low growth rates is unfavorable because of the
high maintenance requirements which result in low biomass yields. At high light supply rates, biomass yields will decrease
due to light saturation effects. Thus, to optimize biomass yield on light energy in photobioreactors, an optimum between low
and high light supply rates should be found. These simulations show that metabolic flux analysis can be used as a tool to
gain insight into the metabolism of algae and ultimately can be used for the maximization of algal biomass and product yield. 相似文献
4.
Elizabeth Kebede-Westhead Carolina Pizarro Walter W. Mulbry 《Journal of applied phycology》2006,18(1):41-46
Cultivating algae on nitrogen (N) and phosphorus (P) in animal manure effluents presents an alternative to the current practice of land application. The objective of this study was to determine how algal productivity, nutrient removal efficiency, and elemental composition of turf algae change in response to different loading rates of raw swine manure effluent. Algal biomass was harvested weekly from laboratory scale algal turf scrubber units using four manure effluent loading rates (0.24, 0.40, 0.62 and 1.2 L m−2 d−1) corresponding to daily loading rates of 0.3–1.4 g total N and 0.08–0.42 g total P. Mean algal productivity values increased from 7.1 g DW m−2 d−1 at the lowest loading rate (0.24 L m−2 d−1) to 9.4 g DW m−2 d−1 at the second loading rate (0.40 L m−2 d−1). At these loading rates, algal N and P accounted for> 90% of input N and 68–76% of input P, respectively. However, at higher loading rates algal productivity did not increase and was unstable at the highest loading rate. Mean N and P contents in the dried biomass increased 1.5 to 2.0-fold with increasing loading rate up to maximums of 5.7% N and 1.8% P at 1.2 L m−2 d−1. Biomass concentrations of Al, Ca, Cd, Fe, K, Mg, Mn, Mo, Si, and Zn increased 1.2 to 2.6-fold over the 5-fold range of loading rate. Biomass concentrations of Cd, K, Pb, and Si did not increase significantly with loading rate. At the loading rate of 0.40 L m−2 d−1 (corresponding to peak productivity) the mean concentrations of individual components in the algal biomass were (in mg kg−1): 250 (Al), 4900 (Ca), 0.30 (Cd), 1050 (Fe), 3.4 (Pb), 2500 (Mg), 105 (Mn), 6.0 (Mo), 7,500 (K), and 510 (Zn). At these concentrations, heavy metals in the algal biomass would not be expected to reduce its value as a soil or feed amendment. 相似文献
5.
R. Jan Stevenson Steven T. Rier Catherine M. Riseng Richard E. Schultz Michael J. Wiley 《Hydrobiologia》2006,561(1):149-165
Responses of stream algal biomass to nutrient enrichment were studied in two regions where differences in hydrologic variability
cause great differences in herbivory. Around northwestern Kentucky (KY) hydrologic variability constrains invertebrate biomass
and their effects on algae, but hydrologic stability in Michigan (MI) streams permits accrual of high herbivore densities
and herbivory of benthic algae. Multiple indicators of algal biomass and nutrient availability were measured in 104 streams
with repeated sampling at each site over a 2−month period. Many measures of algal biomass and nutrient availability were positively
correlated in both regions, however the amount of variation explained varied with measures of biomass and nutrient concentration
and with region. Indicators of diatom biomass were higher in KY than MI, but were not related to nutrient concentrations in
either region. Chl a and % area of substratum covered by Cladophora were positively correlated to nutrient concentrations in both regions. Cladophora responded significantly more to nutrients in MI than KY. Total phosphorus (TP) and total nitrogen (TN) explained similar
amounts of variation in algal biomass, and not significantly more variation in biomass than dissolved nutrient concentrations.
Low N:P ratios in the benthic algae indicated N as well as P may be limiting their accrual. Most observed responses in benthic
algal biomass occurred in nutrient concentrations between 10 and 30 μg TP l−1 and between 400 and 1000 μg TN l−1. 相似文献
6.
Chris J. Hulatt Aino-Maija Lakaniemi Jaakko A. Puhakka David N. Thomas 《Bioenergy Research》2012,5(3):669-684
Mass culture of microalgae is a potential alternative to cultivation of terrestrial crops for bioenergy production. However, microalgae require nitrogen fertiliser in quantities much higher than plants, and this has important consequences for the energy balance of these systems. The effect of nitrogen fertiliser supplied to microalgal bubble-column photobioreactor cultures was investigated using different nitrogen sources (nitrate, urea, ammonium) and culture conditions (air, 12% CO2). In 20 L cultivations, maximum biomass productivity for Chlorella vulgaris cultivated using nitrate and urea was 0.046 and 0.053 g L−1 day−1, respectively. Maximum biomass productivity for Dunaliella tertiolecta cultivated using nitrate, urea and ammonium was 0.033, 0.038 and 0.038 g L−1 day−1, respectively. In intensive bubble-column photobioreactors using 12% CO2, maximum productivity reached 0.60 and 0.83 g L−1 day−1 for C. vulgaris and D. tertiolecta, respectively. Recycling of nitrogen within the photobioreactor system via algal exudation of nitrogenous compounds and bacterial activity was identified as a potentially important process. The energetic penalty incurred by supply of artificial nitrogen fertilisers, phosphorus, power and CO2 to microalgal photobioreactors was investigated, although analysis of all energy burdens from biomass production to usable energy carriers was not conducted. After subtraction of the power, nitrogen and phosphorus energy burdens, maximum net energy ratios for C. vulgaris and D. tertiolecta cultivated in bubble columns were 1.82 and 2.10. Assuming CO2 was also required from a manufactured source, the net energy ratio decreased to 0.09 and 0.11 for C. vulgaris and D. tertiolecta, so that biomass production in this scenario was unsustainable. Although supply of nitrogen is unlikely to be the most energetically costly factor in sparged photobioreactor designs, it is still a very significant penalty. There is a need to optimise both cultivation strategies and recycling of nitrogen in order to improve performance. Data are supported by measurements including biochemical properties (lipid, protein, heating value) and bacterial number by epifluorescence microscopy. 相似文献
7.
Response of Periphytic Algae to Gradients in Nitrogen and Phosphorus in Streamside Mesocosms 总被引:2,自引:1,他引:1
In this study we manipulated both nitrogen and phosphorus concentrations in stream mesocosms to develop quantitative relationships
between periphytic algal growth rates and peak biomass with inorganic N and P concentrations. Stream water from Harts Run,
a 2nd order stream in a pristine catchment, was constantly added to 36 stream-side stream mesocosms in low volumes and then
recirculated to reduce nutrient concentrations. Clay tiles were colonized with periphyton in the mesocosms. Nutrients were
added to create P and N concentrations ranging from less than Harts Run concentrations to 128 μg SRP l−1 and 1024 μg NO3-N l−1. Algae and water were sampled every 3 days during colonization until periphyton communities reached peak biomass and then
sloughed. Nutrient depletion was substantial in the mesocosms. Algae accumulated in all streams, even streams in which no
nutrients were added. Nutrient limitation of algal growth and peak biomass accrual was observed in both low P and low N conditions.
The Monod model best explained relationships between P and N concentrations and algal growth and peak biomass. Algal growth
was 90% of maximum rates or higher in nutrient concentrations 16 μg SRP l−1 and 86 μg DIN l−1. These saturating concentrations for growth rates were 3–5 times lower than concentrations needed to produce maximum biomass.
Modified Monod models using both DIN and SRP were developed to explain algal growth rates and peak biomass, which respectively
explained 44 and 70% of the variance in algal response. 相似文献
8.
Chlorella kessleri was cultivated in artificial wastewater using diurnal illumination of 12 h light/12 h dark (L/D) cycles. The inoculum density
was 105 cells/mL and the irradiance in light cycle was 45 μmol m2 s−1 at the culture surface. As a control culture, another set of flasks was cultivated under continuous illumination. Regardless
of the illumination scheme, the total organic carbon (TOC) and chemical oxygen demand (COD) was reduced below 20% of the initial
concentration within a day. However, cell concentration under the L/D lighting scheme was lower than that under the continuous
illuminating scheme. Thus the specific removal rate of organic carbon under L/D cycles was higher than that under continuous
illumination.
This result suggested thatC. kessleri grew chemoorganotrophically in the dark periods. After 3 days, nitrate was reduced to 136.5 and 154.1 mg NO3
−-N/L from 168.1 mg NO3
−-N/L under continuous illumination and under diurnal cycles, respectively. These results indicate nitrate removal efficiency
under continuous light was better than that under diurnal cycles. High-density algal cultures using optimized photobioreactors
with diurnal cycles will save energy and improve organic carbon sources removal. 相似文献
9.
Clemens G. Borkenstein Josef Knoblechner Heike Frühwirth Michael Schagerl 《Journal of applied phycology》2011,23(1):131-135
The present study reviews the options of cultivating the green alga, Chlorella emersonii, under photoautotrophic conditions with flue gas derived from a cement plant. It was conducted in the Lafarge Perlmooser
plant in Retznei, Austria, where stone coal and various surrogate fuels such as used tyres, plastics and meat-and-bone meal
are incinerated for heating limestone. During 30 days of cultivation, flue gas had no visible adverse effects compared to
the controls grown with pure CO2. The semi-continuous cultivation with media recycling was performed in 5.5-L pH-stat photobioreactors. The essay using CO2 from flue gas yielded a total of 2.00 g L−1 microalgal dry mass and a CO2 fixation of 3.25 g L−1. In the control, a total of 2.06 g L−1 dry mass was produced and 3.38 g L−1 CO2 was fixed. Mean growth rates were between 0.10 day−1 (control) and 0.13 day−1 (flue gas). No accumulation of flue gas residues was detected in the culture medium. At the end of the experiment, however,
the concentration of lead was three times higher in algal biomass compared to the control, indicating that cultures aerated
with this type of flue gas should not be used as food supplements or animal feed. 相似文献
10.
An alternative to land spreading of manure effluents is to mass-culture algae on the N and P present in the manure and convert
manure N and P into algal biomass. The objective of this study was to determine how the fatty acid (FA) content and composition
of algae respond to changes in the type of manure, manure loading rate, and to whether the algae was grown with supplemental
carbon dioxide. Algal biomass was harvested weekly from indoor laboratory-scale algal turf scrubber (ATS) units using different
loading rates of raw and anaerobically digested dairy manure effluents and raw swine manure effluent. Manure loading rates
corresponded to N loading rates of 0.2 to 1.3 g TN m−2 day−1 for raw swine manure effluent and 0.3 to 2.3 g TN m−2 day−1 for dairy manure effluents. In addition, algal biomass was harvested from outdoor pilot-scale ATS units using different loading
rates of raw and anaerobically digested dairy manure effluents. Both indoor and outdoor units were dominated by Rhizoclonium sp. FA content values of the algal biomass ranged from 0.6 to 1.5% of dry weight and showed no consistent relationship to
loading rate, type of manure, or to whether supplemental carbon dioxide was added to the systems. FA composition was remarkably
consistent among samples and >90% of the FA content consisted of 14:0, 16:0, 16:1ω7, 16:1ω9, 18:0, 18:1ω9, 18:2 ω6, and 18:3ω3. 相似文献
11.
Yeo-Joong Yoon Hosakatte Niranjana Murthy Eun Joo Hahn Kee Yoeup Paek 《Journal of Plant Biology》2007,50(5):573-576
We investigated the factors that affect biomass production fromAnoectochilus formosanus in a bioreactor system. Those factors included inoculum size, initial sucrose concentration, media supplements, photosynthetic
photon flux density (PPFD), and cuIturing methods. An inoculum size of 8 g L−1 was most suitable for shoot proliferation; biomass accumulation was optimized when the medium was supplemented with 3% sucrose
compared with sucrose-free media or those containing concentrations of 6% or 9%. This accumulation also was enhanced under
a PPFD of 50 μmol m2 s−1. Likewise, the addition of coconut water (50 mL L−1) plus activated charcoal (0.5 mg L−1) to our Hyponex medium proved most beneficial. Comparative studies among three bioreactor systems — continuous immersion,
raft (net), and temporary immersion (the ebb and flood system) — revealed that shoot proliferation and biomass accumulation
were more efficient when culturing was performed under continuous immersion. 相似文献
12.
Algal biofuel production has gained a renewed interest in recent years but is still not economically feasible due to several
limitations related to algal culture. The objective of this study is to explore a novel attached culture system for growing
the alga Chlorella sp. as biodiesel feedstock, with dairy manure wastewater being used as growth medium. Among supporting materials tested for
algal attachment, polystyrene foam led to a firm attachment, high biomass yield (25.65 g/m2, dry basis), and high fatty acid yield (2.31 g/m2). The biomass attached on the supporting material surface was harvested by scraping; the residual colonies left on the surface
served as inoculum for regrowth. The algae regrowth on the colony-established surface resulted in a higher biomass yield than
that from the initial growth on fresh surface due to the downtime saved for initial algal attachment. The 10-day regrowth
culture resulted in a high biodiesel production potential with a fatty acid methyl esters yield of 2.59 g/m2 and a productivity of 0.26 g/m−2 day−1. The attached algal culture also removed 61–79% total nitrogen and 62–93% total phosphorus from dairy manure wastewater,
depending on different culture conditions. The biomass harvested from the attached growth system (through scraping) had a
water content of 93.75%, similar to that harvested from suspended culture system (through centrifugation). Collectively, the
attached algal culture system with polystyrene foam as a supporting material demonstrated a good performance in terms of biomass
yield, biodiesel production potential, ease to harvest biomass, and physical robustness for reuse. 相似文献
13.
Picoeukaryotes dominate the phytoplankton of Lake Balaton—the largest shallow lake in Central Europe—in the winter period.
We examined the annual dynamics of picoplankton abundance and composition in the lake in order to establish if the picoeukaryotes
merely survive the harsher winter conditions or they are able to grow in the ice-covered lake when the entire phytoplankton
is limited by low light and temperature. Lake Balaton has an annual temperature range of 1–29°C, and it is usually frozen
between December and February for 30–60 days. In the spring-autumn period phycocyanin and phycoerythrin rich Cyanobacteria
are the dominant picoplankters, and picoeukaryotes are negligible. Our five-year study shows the presence of three types of
picophytoplankton assemblages in Lake Balaton: (1) Phycoerythrin-rich Cyanobacteria—the dominant summer picoplankters in the
mesotrophic lake area; (2) Phycocyanin-rich Cyanobacteria—the most abundant summer picoplankters in the eutrophic lake area
and; (3) Picoeukaryotes—the dominant winter picoplankters in the whole lake. The observed winter abundance of picoeukaryotes
was high (up to 3 × 105 cells ml−1), their highest biomass (520 μg l−1) exceeded the maximum summer biomass of picocyanobacteria (500 μg l−1). Our results indicate that the winter predominance of picoeukaryotes is a regular phenomenon in Lake Balaton, irrespective
of the absence or presence of the ice cover. Picoeukaryotes are able to grow at as low as 1–2°C water temperature, while the
total phytoplankton biomass show the lowest annual values in the winter period. In agreement with earlier findings, the contribution
of picocyanobacteria to the total phytoplankton biomass in Lake Balaton is inversely related to the total phytoplankton biomass,
whereas no such relationship was observable in the case of picoeukaryotes. 相似文献
14.
Landfast ice algal communities were studied in the strongly riverine-influenced northernmost part of the Baltic Sea, the Bothnian
Bay, during the winter-spring transition of 2004. The under-ice river plume, detected by its low salinity and elevated nutrient
concentrations, was observed only at the station closest to the river mouth. The bottommost ice layer at this station was
formed from the plume water (brine volume 0.71%). This was reflected by the low flagellate-dominated (93%) algal biomass in
the bottom layer, which was one-fifth of the diatom-dominated (74%) surface-layer biomass of 88 μg C l−1. Our results indicate that habitable space plays a controlling role for ice algae in the Bothnian Bay fast ice. Similarly
to the water column in the Bothnian Bay, average dissolved inorganic N:P-ratios in the ice were high, varying between 12 and
265. The integrated chlorophyll a (0.1–2.2 mg m−2) and algal biomass in the ice (1–31 mg C m−2) correlated significantly (Spearman ρ = 0.79), with the highest values being measured close to the river mouth in March and during the melt season in April. Flagellates
<20 μm generally dominated in both the ice and water columns in February–March. In April the main ice-algal biomass was composed
of Melosira arctica and unidentified pennate diatoms, while in the water column Achnanthes taeniata, Scrippsiella hangoei and flagellates dominated. The photosynthetic efficiency (0.003–0.013 (μg C [μg chl a
−1] h−1)(μE m−2s−1)−1) and maximum capacity (0.18–1.11 μg C [μg chl a
−1] h−1) could not always be linked to the algal composition, but in the case of a clear diatom dominance, pennate species showed
to be more dark-adapted than centric diatoms. 相似文献
15.
Mei-Chun Lu 《Plant Cell, Tissue and Organ Culture》2004,78(1):93-96
High frequency plant regeneration was induced from protocorm-derived callus cultured on half-strength of Murashige—Skoog medium
with 2,4-dichlorophenoxyacetic acid (2,4-D, 0–5 mg l−1) and 1-phenyl-3-(1,2,3-thiadiazol-5-yl, 0–1 mg l−1) urea (TDZ) in the dark. Twelve totipotent callus lines were selected within 76 callus lines regenerated on half-strength
of Murashige—Skoog (MS) medium with 0.5 mg l−1 TDZ. The proliferation rate was 4–5-fold in fresh weight after 30 days of culture on half-strength MS medium containing 5
mg l−1 2,4-D and 0.5 mg l−1 TDZ in the dark. The maximum number of shoot buds generated by 0.01 g callus explant was 134 after 4 months of culture. These
calli were regenerated to plantlets via protocorm-like bodies (PLBs) after 75–150 days of culture. The shoots, with two true
leaves, were transferred to hormone-free medium, rooting and eventually formed plantlets. Totipotent callus lines of Pleione formosana Hayata have been successfully established in this study. 相似文献
16.
Nitrogen and phosphorus are the primary nutrients that affect water quality in streams in the midwestern USA and high concentrations
of these nutrients tend to increase algal biomass. However, how nutrients interact with physical controls in regulating algal
biomass is not well known in agricultural streams. Eighteen streams in east-central Illinois (USA) were sampled during June
and September 2003 to analyze factors possibly regulating algal biomass. Additionally, two shaded and two non-shaded sites
in the Embarras River in east-central Illinois were sampled intensively from June to December 2003. Both sestonic and periphytic
chlorophyll-a (chl-a) were analyzed, and periphytic chl-a was assessed on natural substrata and unglazed ceramic tiles. Although high concentrations of nutrients were found in these
streams (mean total P = 0.09–0.122 mg l−1 and mean NO3-N=4.4–8.4 mg l−1), concentrations of sestonic chl-a were low among all sites and both sampling periods (<18 mg m−3, median values of 5 and 3 in June and September, respectively). Filamentous algae were an important component of the algal
communities in streams with stable substrata. Periphytic chl-a was generally not related to the concentration of N or P in the water column, and in non-shaded streams periphyton appeared
at times to be light-limited due to turbid water. Turbidity was found to be an important factor controlling chl-a on ceramic tiles across the 18 sites and for the Embarras River sites; chl-a decreased exponentially in concentration (132–0 mg m−2) as turbidity increased from 4 to 39 NTU (r
2 = 0.80). In general, the interaction between hydrology and light (turbidity) likely controlled algal biomass in these nutrient-rich,
agricultural streams. 相似文献
17.
Jan-Willem F. Zijffers Klaske J. Schippers Ke Zheng Marcel Janssen Johannes Tramper Ren�� H. Wijffels 《Marine biotechnology (New York, N.Y.)》2010,12(6):708-718
The biomass yield on light energy of Dunaliella tertiolecta and Chlorella sorokiniana was investigated in a 1.25- and 2.15-cm light path panel photobioreactor at constant ingoing photon flux density (930 μmol
photons m−2 s−1). At the optimal combination of biomass density and dilution rate, equal biomass yields on light energy were observed for
both light paths for both microalgae. The observed biomass yield on light energy appeared to be based on a constant intrinsic
biomass yield and a constant maintenance energy requirement per gram biomass. Using the model of Pirt (New Phytol 102:3–37,
1986), a biomass yield on light energy of 0.78 and 0.75 g mol photons−1 and a maintenance requirement of 0.0133 and 0.0068 mol photons g−1 h−1 were found for D. tertiolecta and C. sorokiniana, respectively. The observed yield decreases steeply at low light supply rates, and according to this model, this is related
to the increase of the amount of useable light energy diverted to biomass maintenance. With this study, we demonstrated that
the observed biomass yield on light in short light path bioreactors at high biomass densities decreases because maintenance
requirements are relatively high at these conditions. All our experimental data for the two strains tested could be described
by the physiological models of Pirt (New Phytol 102:3–37, 1986). Consequently, for the design of a photobioreactor, we should maintain a relatively high specific light supply rate. A process
with high biomass densities and high yields at high light intensities can only be obtained in short light path photobioreactors. 相似文献
18.
The green microalga Chlorella zofingiensis can produce the ketocarotenoid astaxanthin under heterotrophic culture conditions. Here we report the growth-associated biosynthesis
of astaxanthin in this biotechnologically important alga. With glucose as sole carbon and energy source, C. zofinginesis grew fast in the dark with rapid exhaustion of nitrogen and carbon sources from media, leading to a high specific growth
rate (0.034 h−1). Cultures started at a cell concentration of about 3.4 × 109 cells l−1 reached, after 6 days, standing biomass values of 1.6 × 1011 cells or 8.5 g dry weight l−1. Surprisingly, the biosynthesis of astaxanthin was found to start at early exponential phase, independent of cessation of
cell division. A general trend was observed that the culture conditions benefiting cell growth also benefited astaxanthin
accumulation, indicating that astaxanthin was a growth-associated product in this alga. The maximum cell dry biomass and astaxanthin
yield were 11.75 g l−1 and 11.14 mg l−1 (about 1 mg g−1), simultaneously obtained in the fed-batch culture with a combined glucose–nitrate mixture addition, which were the highest
ever reported in dark-heterotrophic algal cultures. The possible reasons why dark-heterotrophic C. zofingiensis could produce astaxanthin during the course of cell growth were discussed. 相似文献
19.
High-density algal photobioreactors using light-emitting diodes 总被引:1,自引:0,他引:1
Lack of high-density algal photobioreactors (PBR) has been a limitation in exploiting the biotechnological potential of algae. Recent developments of highly efficient light-emitting diodes (LED using gallium aluminum arsenide chips) have made the development of a small LED-based PBR possible. We have calculated theoretical values of gas mass transfer requirements and light-intensity requirement to support high-density algal cultures for the 680 nm monochromatic red light from LED as a light source. A prototype PBR has been designed based on these calculations. A cell concentration of more than 2 x 10(9) cells/mL (more than 6.6% v%sol;v), cell doubling times as low as 12 h, and an oxygen production rate as high as 10 mmol oxygen/L culture/h were achieved using on-line ultrafiltration to periodically provide fresh medium. (c) 1994 John Wiley & Sons, Inc. 相似文献
20.
In order to provide a better understanding of the dynamics of phytoplankton in the coastal regions of high latitudes, a study
was carried out to estimate the dynamics of carbon biomass of autotrophic and heterotrophic algal groups over the austral
spring-summer 1997/1998 period. At a fixed station located in the central basin (Paso Ancho) of the Straits of Magellan (53°S),
surface water samples were collected at least once a week from September 1997 (early spring) to March 1998 (late summer).
Quantitative analysis of biomass of phytoplankton was estimated from geometric volumes, using non-linear equations, and converted
to biomass. The pattern of chlorophyll a showed a strong temporal variability, with maximum values (mean 2.8 mg m−3) at the austral spring phytoplankton increase or bloom (October/November) and minimum values during early spring (September:
<0.5 mg m−3) and summer (January/March: 0.5–1.0 mg m−3). During the spring bloom, diatoms made up to 90% of the total phytoplankton carbon (0.01–189 μg l−1), followed by a maximum of thecate dinoflagellates (0.08–34 μg l−1), and sporadic high biomass of phytoflagellates during summer. Heterotrophic algal groups such as Gymnodinium and Gyrodinium spp. dominated (70%, in the 5- to 25-μm size range) shortly before the main diatom bloom, and small peaks were observed within
spring and early summer periods (0–0.4 μg l−1). Phytoflagellates dominated earlier (spring) with higher carbon biomass (8 μg l−1) and post-bloom periods (summer) when carbon biomass ranged between 1 and 4 μg l−1.
Accepted: 6 September 2000 相似文献