共查询到20条相似文献,搜索用时 31 毫秒
1.
A. Q. Hurtado A. T. Critchley A. Trespoey G. Bleicher-Lhonneur 《Journal of applied phycology》2008,20(5):551-555
Kappaphycus striatum var. sacol was grown in two separate studies: (1) at two stocking densities, and (2) at four different depths, each for three different
durations of culture (30, 45 and 60 days) in order to determine the growth rate of the seaweed and evaluate the carrageenan
content and its molecular weight. The results demonstrated that stocking density, duration of culture and depth significantly
(P < 0.01) affected the growth rate, carrageenan content and molecular weight of K. striatum var. sacol. Decreasing growth rate was observed at both stocking densities and at four depths as duration of culture increased. A lower
stocking density (500 g m−1line−1) showed a higher growth rate for the shortest durations, i.e. 30 days, as compared to those grown at a higher density. Likewise,
decreasing growth rate was observed as depth increased, except at 50 cm after 60 days of culture. A 45-day culture period
produced the highest molecular weight at both stocking densities (500 g m−1line−1 = 1,079.5 ± 31.8 kDa, 1,000 g m−1line−1 = 1,167 ± 270.6 kDa). ‘Sacol’ grown for 30 days at 50 cm (1,178 kDa) to 100 cm (1,200 kDa) depth showed the highest values
of molecular weight of carrageenan extracted. The results suggested that K. striatum var. sacol is best grown at a stocking density of 500 g m−1line−1, at a depth of 50–100 cm, and for a duration of 30 days in order to provide the highest growth rate, carrageenan content
and molecular weight. 相似文献
2.
E. F. Cox 《Coral reefs (Online)》2007,26(3):721-724
Bleaching is generally expected to produce detrimental impacts on coral reproduction. This study compared the fecundity of
bleached and unbleached colonies of the Hawaiian coral Montipora capitata. It was hypothesized that bleaching would have no effect on reproduction because previous studies have shown that Montipora capitata can increase heterotrophic feeding following bleaching. Reproductive parameters, total reproductive output (bundles released
ml−1 coral colony), number of eggs bundle−1, and egg size, measured in the summer of 2005 did not differ between colonies that bleached or did not bleach during 2004.
These data were collected following a single bleaching event and cannot be used to predict the outcome should bleaching episodes
become more frequent or severe. 相似文献
3.
Abdolmohammad Abedian Kennari Nasrollah Ahmadifard Maryam Fallahi Kapourchali Jafar Seyfabadi 《Biologia》2008,63(3):407-411
The rotifer, Brachionus calyciflorus, was grown with two algae species (Chlorella sp. and Scenedesmus obliquus) at different concentrations (0.1, 1 and 10 × 106 cells ml−1). The body size (lorica biovolume) of individual rotifer and their egg size were measured when the populations were roughly
in the exponential phase of population growth. The body size of the rotifers differed significantly (P < 0.05) among the two algae species used, however this effect was not observed for egg size. The body size of rotifers fed
on higher densities of Chlorella sp. (10 × 106 cells ml−1) was significantly larger than for those fed on lower and medium densities (0.1 and 1 × 106 cells ml−1). Body size and egg size of rotifers fed with different amounts of Scenedesmus did not differ significantly. The egg size was significantly larger at higher food level of Chlorella. A significantly positive correlation was observed between the adult rotifer body size and their egg size. 相似文献
4.
Jie Chen Heming Chen Xiangchen Zhu Yinghua Lu Shang-Tian Yang Zhinan Xu Peilin Cen 《Applied microbiology and biotechnology》2009,82(2):241-248
The production of recombinant glycoproteins in Dictyostelium discoideum by conventional cell culture methods was limited by low cell density as well as low growth rate. In this work, cotton towel
with a good adsorption capability for D. discoideum cells was used as the immobilization matrix in an external fibrous bed bioreactor (FBB) system. With batch cultures in the
FBB, the concentration of immobilized cells in the cotton fiber carrier increased to 1.37 × 108 cells per milliliter after 110-h cultivation, which was about tenfold higher than the maximal cell density in the conventional
free-cell culture. Correspondingly, a high concentration of soluble human Fas ligand (hFasL; 173.7 μg l−1) was achieved with a high productivity (23 μg l−1 h−1). The FBB system also maintained a high density of viable cells for hFasL production during repeated-batch cultures, achieving
a productivity of 9∼10 μg l−1 h−1 in all three batches studied during 15 days. The repeated-batch culture using immobilized cells of D. discoideum in the FBB system thus provides a good method for long-term and high-level production of hFasL. 相似文献
5.
Noscoc
flagelliforme is a terrestrial macroscopic cyanobacterium with high economic value. Free-living cells that were separated from a natural
colony of N. flagelliforme were cultivated in a 20-L photobioreactor for 16 days at five agitation rates with impeller tip speeds at 0.3, 0., 0.8, 1.0,
and 1.5 m·s−1. With different impeller tip speeds there were significant differences in the cell growth and polysaccharide production,
and different types of cell colonies appeared because of different shear forces caused by agitation. At harvest time, cell
concentrations with tip speeds of 0.8 and 1.0 m·s−1 were clearly higher than those with the other three tip speeds, but dry cell weights with the tip speeds of 0.3, 0.5, 0.8,
and 1.0 m·s−1 were almost the same. The highest RPS (polysaccharide that released into liquid medium) production was obtained with the
tip speeds of 0.8 and 1.0 m·s−1, while the highest EPS (polysaccharide that formed capsule or slime layer) production was obtained with the tip speed of
0.5 m·s−1. The tip speed of 1.5 m·s−1 was harmful for both cell growth and polysaccharide production, indicating that an appropriate shear force was needed in
the liquid suspension culture of N. flagelliforme. 相似文献
6.
A reciprocal transplant experiment (RTE) of the reef-building coral Porites lobata between shallow (1.5 m at low tide) back reef and forereef habitats on Ofu and Olosega Islands, American Samoa, resulted
in phenotypic plasticity for skeletal characteristics. Transplants from each source population (back reef and forereef) had
higher skeletal growth rates, lower bulk densities, and higher calcification rates on the back reef than on the forereef.
Mean annual skeletal extension rates, mean bulk densities, and mean annual calcification rates of RTE groups were 2.6–9.8 mm year−1, 1.41–1.44 g cm−3, and 0.37–1.39 g cm−2 year−1 on the back reef, and 1.2–4.2 mm year−1, 1.49–1.53 g cm−3, and 0.19–0.63 g cm−2 year−1 on the forereef, respectively. Bulk densities were especially responsive to habitat type, with densities of transplants increasing
on the high energy forereef, and decreasing on the low energy back reef. Skeletal growth and calcification rates were also
influenced by source population, even though zooxanthella genotype of source colonies did not vary between sites, and there
was a transplant site x source population interaction for upward linear extension. Genetic differentiation may explain the
source population effects, or the experiment may have been too brief for phenotypic plasticity of all skeletal characteristics
to be fully expressed. Phenotypic plasticity for skeletal characteristics likely enables P. lobata colonies to assume the most suitable shape and density for a wide range of coral reef habitats. 相似文献
7.
Zhibiao Xu Xiaojun Yan Luqing Pei Qijun Luo Jilin Xu 《Journal of applied phycology》2008,20(3):237-243
Changes in the composition of fatty acids and sterols of Pavlova viridis cultured in an air-lift photobioreactor were studied using gas chromatography-mass spectrometry (GC-MS). The results show
that radical changes in fatty acid and sterol contents and compositions occurred during growth phase transitions: the total
lipid increased along with the culture age, from 166.4 mg g−1 (late exponential phase) to 232.7 mg g−1 (linear phase), and increased further to be 235.1 mg g−1 in the stationary phase. Polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic acid (EPA), decreased along with
the culture time, PUFAs, and EPA contents maximized in the late exponential phase to become 46.2 mg g−1 and 22.1 mg g−1 respectively; there was no significant change in docosahexaenoic acid (DHA) content during the whole growth phase, although
it reached the peak in the linear phase with 3.5 mg g−1. As for the sterols, two unique sterols with two hydroxyl groups, termed pavlovols, were observed. 4α,24-Dimethylcholestan-3β,4β-diol,
one of the pavlovols, increased almost 2-fold from the late exponential phase (2.5 mg g−1) to the stationary phase (4.3 mg g−1). On the contrary, the contents of stigmasterol and sitosterol decreased with culture age, with the maximum content of 2.4 mg
g−1 and 3.1 mg g−1, both obtained in the late exponential phase, respectively. The results indicate that growth phase control could be used
as a methodology to optimize the total lipid, EPA, PUFA, and sterol contents with the potential for both aquaculture feeds
and nutraceutical applications, especially for further research into unique pavlovols. 相似文献
8.
Kameshnee Naidoo Manimaran Ayyachamy Kugen Permaul Suren Singh 《Bioprocess and biosystems engineering》2009,32(5):689-695
Xanthomonas campestris pv phaseoli produced an extracellular endoinulinase (9.24 ± 0.03 U mL−1) in an optimized medium comprising of 3% sucrose and 2.5% tryptone. X. campestris pv. phaseoli was further subjected to ethylmethanesulfonate mutagenesis and the resulting mutant, X. campestris pv. phaseoli KM 24 demonstrated inulinase production of 22.09 ± 0.03 U mL−1 after 18 h, which was 2.4-fold higher than that of the wild type. Inulinase production by this mutant was scaled up using
sucrose as a carbon source in a 5-L fermenter yielding maximum volumetric (21,865 U L−1 h−1) and specific (119,025 U g−1 h−1) productivities of inulinase after 18 h with an inulinase/invertase ratio of 2.6. A maximum FOS production of 11.9 g L−1 h−1 and specific productivity of 72 g g−1 h−1 FOS from inulin were observed in a fermenter, when the mutant was grown on medium containing 3% inulin and 2.5% tryptone.
The detection of mono- and oligosaccharides in inulin hydrolysates by TLC analysis indicated the presence of an endoinulinase.
This mutant has potential for large-scale production of inulinase and fructooligosaccharides. 相似文献
9.
Y. Kitaya L. Xiao A. Masuda T. Ozawa M. Tsuda K. Omasa 《Journal of applied phycology》2008,20(5):737-742
Symbiotic dinoflagellates of the species Amphidinium are expected to be pharmaceutically useful microalgae because they produce antitumor macrolides. A microalgae production
system with a large number of cells at a high density has been developed for the efficient production of macrolide compounds.
In the present study, the effects of culture conditions on the cellular growth rate of dinoflagellates were investigated to
determine the optimum culture conditions for obtaining high yields of microalgae. Amphidinium species was cultured under conditions with six temperature levels (21–35°C), six levels of photosynthetic photon flux density
(15–70 μmol photons m−2 s−1), three levels of CO2 concentration (0.02–0.1%), and three levels of O2 concentration (0.2–21%). The number of cells cultured in a certain volume of solution was monitored microscopically and the
cellular growth rate was expressed as the specific growth rate. The maximum specific growth rate was 0.022 h−1 at a temperature of 26°C and O2 concentration of 5%, and the specific growth rate was saturated at a CO2 concentration of 0.05%, a photosynthetic photon flux density of 35 μmol photons m−2 s−1 and a photoperiod of 12 h day−1 upon increasing each environmental parameter. The results demonstrate that Amphidinium species can multiply efficiently under conditions of relatively low light intensity and low O2 concentration. 相似文献
10.
An efficient succinic acid production process in a metabolically engineered <Emphasis Type="Italic">Corynebacterium glutamicum</Emphasis> strain 总被引:1,自引:0,他引:1
Okino S Noburyu R Suda M Jojima T Inui M Yukawa H 《Applied microbiology and biotechnology》2008,81(3):459-464
A Corynebacterium glutamicum strain (ΔldhA-pCRA717) that overexpresses the pyc gene encoding pyruvate carboxylase while simultaneously exhibiting a disrupted ldhA gene encoding l-lactate dehydrogenase was investigated in detail for succinic acid production. Succinic acid was shown to be efficiently
produced at high-cell density under oxygen deprivation with intermittent addition of sodium bicarbonate and glucose. Succinic
acid concentration reached 1.24 M (146 g l−1) within 46 h. The yields of succinic acid and acetic acid from glucose were 1.40 mol mol−1 (0.92 g g−1) and 0.29 mol mol−1 (0.10 g g−1), respectively. The succinic acid production rate and yield depended on medium bicarbonate concentration rather than glucose
concentration. Consumption of bicarbonate accompanied with succinic acid production implied that added bicarbonate was used
for succinic acid synthesis. 相似文献
11.
The effects of temperature and light on the growth and geosmin production of Lyngbya kuetzingii were determined. Of the three temperatures tested, 10, 25 and 35°C, the maximal geosmin concentration and geosmin productivity
were yielded at 10°C, while the highest chl a production was observed at 25°C. In the studies on light intensity, the maximal geosmin concentration and geosmin productivity
were observed at 10 μmol m−2 s−1, while the highest chl a production was at 20 μmol m−2 s−1. It was suggested that more geosmin was synthesized with lower chl a demand. Meanwhile, the relative amounts of extra- and intracellular geosmin were investigated. Under optimum growth conditions
(20 μmol m−2 s−1, 25°C; BG-11 medium), the amounts of extracellular geosmin increased as the growth progressed and reached the maximum in
the stationary phase, while the intracellular geosmin reached its maximum value in the late exponential phase, and then began
to decline. However, under the low temperature (10°C) or light (10 μmol m−2 s−1) conditions, more intracellular geosmin was synthesized and mainly accumulated in the cells. The proportions of extracellular
geosmin were high, to 33.33 and 32.27%, respectively, during the stationary phase at 35°C and 20 μmol m−2 s−1. It was indicated that low temperature or light could stimulate geosmin production and favor the accumulation of geosmin
in cells, while more intracellular geosmin may be released into the medium at higher temperatures or optimum light intensity. 相似文献
12.
13.
The rhabditid nematodes Steinernema carpocapsae and Steinernema feltiae are used in biological control of insect pests. Mass production is done in liquid culture media pre-incubated with their
bacterial symbionts Xenorhabdus nematophila and Xenorhabdus bovienii, respectively, before nematode dauer juveniles (DJs) are inoculated. As a response to food signals produced by the bacterial
symbionts, the DJs exit from the developmentally arrested dauer stage (they recover development) and grow to adults, which
produce DJ offspring. Variable DJ recovery after inoculation often causes process failure due to non-synchronous population
development and low numbers of adult nematodes. This contribution investigated the influence of the bacterial cell density
on DJ recovery and development to adults. At higher density of 1010 bacterial cells ml−1, a higher percentage of DJ recovery was induced, and adults occurred earlier in both Steinernema spp. than at lower density of 109 and 108 cells ml−1. Xenorhabdus symbionts produce phase variants. Recovery in bacteria-free supernatants was lower than in supernatants containing bacterial
cells for both primary and secondary phase Xenorhabdus spp. and lower in secondary than in primary phase supernatants or cell suspensions. In general, recovery was lower for Steinernema feltiae and the time at which 50% of the population had recovered after exposure to the food signal was longer (RT50 = 17.1 h) than for Steinernema carpocapsae (RT50 = 6.6 h). Whereas >90% S. carpocapsae DJs recovered in hemolymph serum of the lepidopteran insect Galleria mellonella, recovery of S. feltiae only reached 31%. Penetration into a host insect prior to exposure to the insect’s food signal did not enhance DJ recovery.
Consequences for liquid culture mass production of the nematodes and differences between species of the genera Steinernema and Heterorhabditis are discussed. 相似文献
14.
Octavio Carvajal-Zarrabal Cirilo Nolasco-Hipólito Kopli B. Bujang Ayaaki Ishizaki 《Journal of industrial microbiology & biotechnology》2009,36(3):409-415
A membrane bioreactor for production of nisin Z was constructed using Lactococcus lactis IO-1 in continuous culture using hydrolyzed sago starch as carbon source. A strategy used to enhance the productivity of
nisin Z was to maintain the cells in a continuous growth at high cell concentration. This resulted in a volumetric productivity
of nisin Z, as 50,000 IU l−1 h−1 using a cell concentration of 15 g l−1, 30°C, pH 5.5 and a dilution rate of 1.24 h−1. Adding 10 g l−1 YE and 2 g l−1 polypeptone, other inducers were unnecessary to maintain production of nisin. The operating conditions of the reactor removed
nisin and lactate, thus minimizing their effects which allowed the maintenance of cells in continuous exponential growth phase
mode with high metabolic activity. 相似文献
15.
Khalilzadeh R Mohammadian-Mosaabadi J Bahrami A Nazak-Tabbar A Nasiri-Khalili MA Amouheidari A 《Journal of industrial microbiology & biotechnology》2008,35(12):1643-1650
The fed-batch process using glucose as the sole source of carbon and energy with exponential feeding rate was carried out
for high cell density cultivation of recombinant Escherichia coli BL21 (DE3) expressing human granulocyte-colony stimulating factor (hG-CSF). IPTG was used to induce the expression of hG-CSF
at 48 g dry cell wt l−1 during high cell density culture of recombinant E. coli BL21 (DE3) [pET23a-g-csf]. The final cell density, specific yield and overall productivity of hG-CSF were obtained as ~64 g
dry cell wt l−1, 223 mg hG-CSF g−1 dry cell wt and 775 mg hG-CSF l−1 h−1, respectively. The resulting purification process used cell lysis, inclusion body (IB) preparation, refolding, DEAE and Butyl-Sepharose.
Effects of different process conditions such as cell lysis and washing of IB were evaluated. The results reveal that the cells
lyzed at 1,200 bar, 99.9% and Triton removed about 64% of the LPS but sarcosyl had no effect on removal of nucleic acids and
LPS. Further analysis show that DEAE column removes DNA about 84%. Cupper concentration was identified as parameter that could
have a significant impact on aggregation, as an unacceptable pharmaceutical form that decrease process yields. The purity
of purified hG-CSF was more than 99%. Also the comparison of activity between purified hG-CSF and commercial form do not show
valuable decrease in activity in purified form. 相似文献
16.
The growth and toxin content of the dinoflagellate Alexandrium tamarense ATHK was markedly affected by culture methods. In early growth phase at lower cell density static or mild agitation methods were beneficial to growth, but continuous agitation or aeration, to some extent, had an adverse effect on cell growth. Static culture in 2 L Erlenmeyer flasks had the highest growth rate (0.38 d−1) but smaller cell size compared with other culture conditions. Cells grown under aerated conditions possessed low nitrogen and phosphorus cell yields, namely high N and P cell-quota. At day 18, cells grown in continuous agitated and 1 h aerated culture entered the late stationary phase and their cellular toxin contents were higher (0.67 and 0.54 pg cell−1) compared with cells grown by other culture methods (0.27–0.49 pg cell−1). The highest cell density and cellular toxin content were 17190 cells mL−1 and 1.26 pg cell−1 respectively in an airlift photobioreactor with two-step culture. The results indicate that A. tamarense could be grown successfully in airlift photobioreactor by a two-step culture method, which involved cultivating the cells statically for 4 days and then aerating the medium. This provides an efficient way to enhance cell and toxin yield of A. tamarense. 相似文献
17.
A flat plate, multi-pass air lift reactor (FPALR) for the culture of photosynthetic organisms was constructed from twin wall
acrylic sheet and its performance characterised. When operated at an air input of 2.01 min−1 the multi-pass system had a Reynolds number of 5200 indicating fully turbulent flow. Chlorella vulgaris 211/11c was found to have a stationary phase biomass of 1.48 g 1−1 when grown in the flat plate air lift reactor (FPALR) at 100 μmol m−2s−1 compared to 1.11 g 1−1 when cultured in the continually stirred tank reactor (CSTR) at the same PFD (photon flux density). The same organism cultured
at 200 μmol m−2s−1 achieved a stationary phase biomass of 1.71 g 1−1 in the FPALR. In contrast, Scenedesmus sp. produced a stationary phase biomass of 2.27 g1−1 and 1.27 g1−1, when cultured at 100 μmol m−2s−1 in the FPALR and the CSTR respectively. The growth rates of both organisms were also higher in the PFALR. 相似文献
18.
Xiangyuan Deng Song Qin Qun Zhang Peng Jiang Yulin Cui Xiaokun Li 《Plant Cell, Tissue and Organ Culture》2009,97(3):253-261
A human acidic fibroblast growth factor gene, hafgf, was successfully transferred into Laminaria japonica (kelp) gametophytes via microprojectile bombardment using the biolistic PDS-1000/He gene gun. Following phosphinothricin
screening, PCR detection and Southern blot analysis, transgenic L. japonica gametophytes were cultivated in an illuminated bubble-column bioreactor to optimize growth conditions. A maximal final dry
cell density of 1,695 mg l−1 was obtained in a batch culture having an initial dry cell density of 129.75 mg l−1. This was achieved using an aeration rate of 1.08 l air min−1 l−1 culture in a medium containing 1.5 mM inorganic nitrate and 0.15 mM phosphate. In addition, the relationship between different
nitrogen sources and growth of transgenic gametophytes indicated that both urea and sodium nitrate were effective nitrogen
sources for cell growth, while ammonium ions inhibited growth of these gametophytes. 相似文献
19.
Experiments were carried out to investigate interspecific interactions between the rotifer Brachionus plicatilis and two harmful algal bloom (HAB) species using single and mixed culture methods. B. plicatilis populations and the growth of two algae were compared at different algal cell densities. The results demonstrate that B. plicatilis obtained sufficient nutrition from Alexandrium tamarense to support net population increase. When exposed to a density of 8 × 104 cells ml−1
A. tamarense, the number of B. plicatilis increased faster than it did when exposed to other four algal densities (16 × 104, 24 × 104, 32 × 104, and 40 × 104 cells ml−1). Cell densities of A. tamarense decreased due to the grazing of B. plicatilis. In contrast, Heterosigma akashiwo had an adverse effect on the B. plicatilis population and its growth was largely unaffected by rotifer grazing. In this case, the B. plicatilis population decreased and H. akashiwo grew at a rate similar to that of a control without addition of rotifers. Mixed culture experiments showed that A. tamarense could partly counteract the effect of H. akashiwo in limiting the rate of population increase of rotifer. In addition, the effect of different initial cell densities on interspecific
competition between A. tamarense and H. akashiwo in mixed culture(s) was also investigated. The results show that A. tamarense competed very successfully when the inoculation proportions of A. tamarense and H. akashiwo were 40:5 and 40:30.
Handling editor: D. Hamilton 相似文献
20.
Expansion of Phragmites australis (Cav.) Trin. ex Steud. (common reed) into stands of Typha spp. (cattail; Typha australis L. and T. x glauca) is common in the wetlands of northwestern Indiana (USA). To understand this phenomenon better, we investigated the production
of shoot sprouts and proportional allocation of biomass as well as a potential role for the water table in the relative dominance
of each species. The reduction in sprouts from rhizomes upon vegetative expansion of Phragmites appeared to be the most likely process causing the decline of Typha. The latter had a shoot density of 39/m2 in plots without Phragmites, but this dropped to 13 shoots m−2 in plots that had been invaded by Phramites. Such a decline was likely caused by reduced reserves; e.g., the belowground biomass of Typha decreased from 11.3 g m−2 without Phragmites to 8.1 g m−2 with Phragmites. The latter also reduced its belowground biomass but not its shoot density in the presence of Typha. The mean weight of Phragmites shoots was 2.9 g, and nearly all produced inflorescences. Meanwhile, Typha failed to develop spadices despite its shoots having a greater biomass (7 g). This suggests that Phragmites is more efficient than Typha in shoot growth. Springtime flooding appeared to promote the sprout of Typha shoots from shallow rhizomes (≈18 cm below the soil surface), whereas the shoot density of Phragmites showed no correlation with water level in that season. Deep-rooted Phragmites (≈39 cm) occurred on both high and low water-table sites, whereas the shallow-rooted Typha was limited to only the former. Phragmites will likely continue its expansion, by vegetative sprouts from rhizomes, into Typha wetlands. 相似文献