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1.
Thirty-five clonal, axenic Arthrospira strains were screened for their ability to grow heterotrophically on six carbon sources (20 mM). Glucose (34 strains) and fructose (24 strains) were the only substrates permitting growth in the dark. In some assays, however, not every replicate grew and, in at least one strain (D867), repeat assays over 2 years on material maintained in the light indicated that the ability to use fructose in the dark had become lost. Four further strains from other culture collections were compared, because they are presumed duplicates of three of the main set of strains; in at least three cases the duplicates of a pair differed in their ability to use fructose in the dark. In another comparison, where straight and helical morphotypes of the same strain could be compared, two of the four straight morphotypes (including one duplicate strain) grew with glucose in the dark, whereas none of the helical morphotypes did so. It is suggested that genetic drift has led to losses in the ability to grow heterotrophically in some strains.Ten of the main set of strains were tested for their ability to grow photoheterotrophically with four of the carbon sources (glucose, maltose, fructose, sucrose). All grew with glucose and maltose, but none with fructose or sucrose, in spite of the fact that eight (of this subset) grew with fructose in the dark. Sucrose led to most of a culture lysing, but often with short fragments of trichome surviving and subsequently giving rise to a normal culture. All the surviving cells in the transitory stage showed the presence of large intrathylakoidal granules, which had disappeared by the time that the culture had returned to a healthy state. Bleaching and recovery were more rapid at 70 than 10 μmol photon m−2 s−1. The presence of DCMU prevented this recovery. There was no bleaching when an inoculum of the recovered material was subcultured to medium with sucrose.  相似文献   

2.
Zengling Ma  Kunshan Gao 《Planta》2009,230(2):329-337
The spiral structure of the cyanobacterium Arthrospira (Spirulina) platensis (Nordst.) Gomont was previously found to be altered by solar ultraviolet radiation (UVR, 280–400 nm). However, how photosynthetic active radiation (PAR, 400–700 nm) and UVR interact in regulating this morphological change remains unknown. Here, we show that the spiral structure of A. platensis (D-0083) was compressed under PAR alone at 30°C, but that at 20°C, the spirals compressed only when exposed to PAR with added UVR, and that UVR alone (the PAR was filtered out) did not tighten the spiral structure, although its presence accelerated morphological regulation by PAR. Their helix pitch decreased linearly as the cells received increased PAR doses, and was reversible when they were transferred back to low PAR levels. SDS-PAGE analysis showed that a 52.0 kDa periplasmic protein was more abundant in tighter filaments, which may have been responsible for the spiral compression. This spiral change together with the increased abundance of the protein made the cells more resistant to high PAR as well as UVR, resulting in a higher photochemical yield.  相似文献   

3.
C-phycocyanin (C-PC) was extracted from fresh Spirulina platensis by deploying a species of non-pathogenic nitrogen-fixing bacteria, namely, Klebsiella pneumoniae. The algal slurry was neither washed nor centrifuged; the bacterial culture was poured into the slurry, the vessel sealed, and crude C-PC extracted after about 24 h. The extraction was clean and efficient, and the purity and concentration of C-PC proved to be of adequate quality.  相似文献   

4.
This paper presents the evaluation of some important parameters for the purification of phycocyanin using ion exchange chromatography. The influences of pH and temperature on the equilibrium partition coefficient were investigated to establish the best conditions for phycocyanin adsorption. The equilibrium isotherm for the phycocyanin-resin system was also determined. The separation of phycocyanin using the Q-Sepharose ion exchange resin was evaluated in terms of the pH and elution volume that improved the increase in purity and recovery. The highest partition coefficients were obtained in the pH range from 7.5 to 8.0 at 25 degrees C. Under these conditions the equilibrium isotherm for phycocyanin adsorption was well described by the Langmuir model, attaining a Q (m) of 22.7 mg/mL and K (d) of 3.1 x 10(-2) mg/mL. The best conditions for phycocyanin purification using the ion exchange column were at pH 7.5 with an elution volume of 36 mL, obtaining 77.3% recovery and a 3.4-fold increase in purity.  相似文献   

5.
The cyanobacterium Spirulina platensis was used to verify the possibility of employing microalgal biomass to reduce the contents of nitrate and phosphate in wastewaters. Batch tests were carried out in 0.5 dm3 Erlenmeyer flasks under conditions of light limitation (40 mol quanta m–2 s–1) at a starting biomass level of 0.50 g/dm3 and varying temperature in the range 23–40°C. In this way, the best temperature for the growth of this microalga (30°C) was determined and the related thermodynamic parameters were estimated. All removed nitrate was used for biomass growth (biotic removal), whereas phosphate appeared to be removed mainly by chemical precipitation (abiotic removal). The best results in terms of specific and volumetric growth rates ( =0.044 day–1, Q x =33.2 mg dm–3 day–1) as well as volumetric rate and final yield of nitrogen removal ( =3.26 mg dm–3 day–1, =0.739) were obtained at 30°C, whereas phosphorus was more effectively removed at a lower temperature. In order to simulate full-scale studies, batch tests of nitrate and phosphate removal were also performed in 5.0 dm3 vessels (mini-ponds) at the optimum temperature (30°C) but increasing the photon fluence rate to 80 mol quanta m–2 s–1 and varying the initial biomass concentration from 0.25 to 0.86 g/dm3. These additional tests demonstrated that an increase in the inoculum level up to 0.75 g/dm3 enhanced both NO3 and PO4 3– removal, confirming a strict dependence of these processes on biomass activity. In addition, the larger surface area of the ponds and the higher light intensity improved removal yields and kinetics compared to the flasks, particularly concerning phosphorus removal ( =0.032–0.050 day–1, Q x =34.7–42.4 mg dm–3 day–1, =3.24–4.06 mg dm–3 day–1, =0.750–0.879, =0.312–0.623 mg dm–3 day–1, and =0.224–0.440).  相似文献   

6.
The effect of salt concentration (NaCl) on growth, fluorescence, photosynthetic activities and pigment content of the cyanobacterium Arthrospira platensis has been investigated over 15 days. It has been observed that high NaCl concentration induces an increase of the growth, photosynthetic efficiency (α), phycobilin/chlorophyll ratio and a slight decrease of dark respiration and compensation points. Moreover, high NaCl concentration enhances photosystem II (PSII) activity compared to photosystem I (PSI). Results show that the phycobilin-PSII energy transfer compared to the chlorophyll-PSII (F695,600/F695,440) increases. However, data obtained about the maximal efficiency of PSII photochemistry are controversial. Indeed, the Fv/Fm ratio decreases in salt adapted cultures, while at the same time the trapping flux per PSII reaction center (TR0/RC) and the probability of electron transport beyond QA (0) remain unchanged at the level of the donor and the acceptor sites of PSII. This effect can be attributed to the interference of phycobilin fluorescence with Chl a when performing polyphasic transient measurements.  相似文献   

7.
A study of the fatty acid composition was made for 35 Arthrospira strains, concentrating on the most abundant fatty acids, the two polyunsaturated C18 acids, linoleic and γ-linolenic acid, and palmitic acid. When grown at 30 C and low irradiance (10 μmol photon m−2 s−1), these three acids together formed 88–92% of total fatty acids. There were considerable differences in the composition of the two polyunsaturated acids. Depending on the strain, linoleic acid formed 13.1–31.5% and γ-linolenic acid formed 12.9–29.4% total fatty acids. In contrast, the range for palmitic acid was narrow: 42.3–47.6% of total fatty acids. Repeat experiments on several strains under defined conditions led to closely similar results for any particular environment, suggesting that fatty acid composition can be used as an aid in differentiating between strains. Five additional strains, which had apparently originated from the same original stock cultures as 3 of the 35 in the main study, but from different culture collections, were also assayed. With four strains the results were similar, irrespective of culture source, but with one strain marked differences occurred, especially in the polyunsaturated C18 fatty acid fraction. These differences were independent of the age of the culture. In addition, straight morphotypes derived during repeat subcultures of four strains; each showed a similar fatty acid composition to that of the helical morphotypes of the same strains. A decrease in temperature from 30 to 20 C, an increase in irradiance (at 30 C) from 10 to 70 μmol photon m−2 s−1 and transfer to dark heterotrophy all favoured an increase in polyunsaturated C18 fatty acids. The highest γ-linolenic acid content of any conditions was found for three strains grown heterotrophically on glucose in the dark at 30 C. A comparative study of six strains of Spirulina confirmed a previous study showing the absence of γ-linolenic acid in all Spirulina strains, thus permitting the separation of these two genera.  相似文献   

8.
The present study examined the possibility of increasing the contents of some bioactive compounds of Spirulina platensis cultivated in medium containing various hydrogen peroxide concentrations (2, 4, 6 and 8 mM) as a model for environmental stress. A positive correlation was observed between the increase of H2O2 and increasing amounts of cellular lipophilic antioxidants (total carotenoids and α-tocopherol) and hydrophilic antioxidants [glutathione (GSH) and ascorbic acid (AsA)]. HPLC profile of carotenoids revealed that algae responded to the change of H2O2 exposure by the accumulation of higher amounts of β-carotene, astaxanthine, luteine, zeaxanthin and cryptoxanthin. S. platensis showed significant linear increase in activities of antioxidant enzymes, i.e., catalase (CAT), peroxidase (PX), ascorbate peroxidase (APX) and superoxide dismutase (SOD), with increasing H2O2 concentrations. A pronounced increase of oxidative lesions’ indexes [thiobarbituric acid reactive substances (TBARS) and paramagnetic radical-EPR signal] was found in algal grown at 8 mM H2O2. These data revealed that S. platensis behaved with different strategies against H2O2 exposure which is dose dependent and their response strongly correlated with the scavenging enzymes (SOD, CAT, PX and APX) and antioxidant compounds (GSH, AsA, β-carotene, astaxanthine and α-tocopherol) in the antioxidant defense systems. Therefore, S. platensis could be considered as good candidates for successful cultivation in artificial open ponds under different environmental conditions, as high value health foods, functional foods and as source of wide spectrum of nutrients.  相似文献   

9.
Palmaria palmata and Gracilaria verrucosa are edible red seaweeds and potential protein sources for human or animal nutrition, so studies were conducted on their in vitro protein digestibility. After 30 min predigestion by pepsin followed by 6 h digestion into a cell dialysis containing porcine pancreatin, the in vitro protein digestibility of P. palmata and G. verrucosa, expressed in regard to casein digestibility, was 4.9% and 42.1%, respectively. The level of protein digestibility seems to be related to the amount of soluble fibre, which was 45.3% and 30.5%, respectively.  相似文献   

10.
The growth and amino acid contents of the cyanobacterium,Spirulina platensis strain NIES 46, were investigated using ammonium, nitrate, nitrite, or urea as the sole nitrogen source in a batch culture. Chlorophylla concentration was highest at 2,096 μg/L in the nitrate group after 10 days of cultivation, while the dry weight ofS. platensis was highest at 4.5 g/L in the ammonium group after 30 days of cultivation. The total amino acid content was highest at 174 mg/g dry weight ofS. platensis in the urea group at the end of the cultivation period, yet the amino acid patterns forS. platensis were similar for all the experimental groups. Therefore, it seemed that the growth and amino acid composition ofS. platensis varied depending on the type of nitrogen sources, while the amino acid patterns were not changed. Also, the most efficient harvesting time forS. platensis seemed to be approximately 10 days after cultivation.  相似文献   

11.
A genetic map of Pinus sylvestris was constructed using ESTP (expressed sequence tag polymorphism) markers and other gene-based markers, AFLP markers and microsatellites. Part of the ESTP markers (40) were developed and mapped earlier in Pinus taeda, and additional markers were generated based on P. sylvestris sequences or sequences from other pine species. The mapping in P. sylvestris was based on 94 F1 progeny from a cross between plus-tree parents E635C and E1101. AFLP framework maps for the parent trees were first constructed. The ESTP and other gene sequence-based markers were added to the framework maps, as well as five published microsatellite loci. The separate maps were then integrated with the aid of AFLPs segregating in both trees (dominant segregation ratios 3:1) as well as gene markers and microsatellites segregating in both parent trees (segregation ratios 1:1:1:1 or 1:2:1). The integrated map consisted of 12 groups corresponding to the P. taeda linkage groups, and additionally three and six smaller groups for E1101 and E635C, respectively. The number of framework AFLP markers in the integrated map is altogether 194 and the number of gene markers 61. The total length of the integrated map was 1,314 cM. The set of markers developed for P. sylvestris was also added to existing maps of two P. taeda pedigrees. Starting with a mapped marker from one pedigree in the source species resulted in a mapped marker in a pedigree of the other species in more than 40% of the cases, with about equal success in both directions. The maps of the two species are largely colinear, even if the species have diverged more than 70 MYA. Most cases of different locations were probably due to problems in identifying the orthologous members of gene families. These data provide a first ESTP-containing map of P. sylvestris, which can also be used for comparing this species to additional species mapped with the same markers.Communicated by C. Möllers  相似文献   

12.
We have investigated the floral ontogeny of Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis (of the eucalypt group, Myrtaceae) using scanning electron microscopy and light microscopy. Several critical characters for establishing relationships between these genera and to the eucalypts have been determined. The absence of compound petaline primordia in Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis excludes these taxa from the eucalypt clade. Post-anthesis circumscissile abscission of the hypanthium above the ovary in Stockwellia, Eucalyptopsis and Allosyncarpia is evidence that these three taxa form a monophyletic group; undifferentiated perianth parts and elongated fusiform buds are characters that unite Stockwellia and Eucalyptopsis as sister taxa. No floral characters clearly associate Arillastrum with either the eucalypt clade or the clade of Stockwellia, Eucalyptopsis and Allosyncarpia.We gratefully acknowledge Clyde Dunlop and Bob Harwood (Northern Territory Herbarium) for collecting specimens of Allosyncarpia, and Bruce Gray (Atherton) for collecting specimens of Stockwellia. The Australian National Herbarium (CANB) kindly lent herbarium specimens of Eucalyptopsis for examination. This research was supported by a University of Melbourne Research Development Grant to Andrew Drinnan.  相似文献   

13.
Arachis correntina (Burkart) Krapov. & W.C. Gregory is a herbaceous perennial leguminous plant growing in the Northeast of the Province Corrientes, Argentina. It is important as forage. The development of new A. correntina cultivars with improved traits could be facilitated through the application of biotechnological strategies. The purpose of this study was to investigate the plant regeneration potential of mature leaves of A. correntina in tissue culture. Buds were induced from both petiole and laminae on 0.7% agar-solidified medium containing 3% sucrose, salts and vitamins from Murashige and Skoog (MS) supplemented with 0.5–25 M thidiazuron (TDZ). Shoot induction was achieved by transference of calli with buds to MS supplemented with 5 M TDZ. Fifty-four percent of the regenerated shoot rooted on MS + 5 M naphthaleneacetic acid. Histological studies revealed that shoots regenerated via organogenesis.  相似文献   

14.
The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae.  相似文献   

15.
Plants were regenerated from root explants of Arabidopsis halleri (L.) O’Kane and Al-Shehbaz via a three-step procedure callus induction, induction of somatic embryos and shoot development. Callus was induced from root segments, leaflets and petiole segments after incubation for 2 weeks in Murashige and Skoog medium (MS) supplemented with 0.5 mg/l−1 (2.26 μM) 2,4-D (2,4-dichlorophenoxyacetic acid) and 0.05 mg/l−1 (0.23 μM) kinetin. Only calli developed from root segments continued to grow when transferred to a regeneration medium containing 2.0 mg/l−1 (9.8 μM) 6-γ-γ-(dimethylallylamino)-purine (2ip) and 0.05 mg/l−1 (2.68 μM) α-naphthalenacetic acid (NAA) and eventually 40 of them developed embryogenic structures. On the same medium 38 of these calli regenerated shoots. Rooting was achieved for 50 of the shoots subcultured in MS medium without hormones. The regeneration ability of callus derived from root cuttings, observed in this study, makes this technique useful for genetic transformation experiments and in vitro culture studies.  相似文献   

16.
Chitinolytic activity of Serratia marcescens Nima (130 U ml−1) was up to 43 times higher than those produced by other S. marcescens strains. This strain synthesized an endochitinase (Chi-60), an exochitinase (Chi-50) and a novel N-acetylglucosaminidase. This latter showed two putative isoforms (Chi-180.5 and Chi-180.8) with isoelectric points of 5 and 8.1, respectively.  相似文献   

17.
An in vitro plant regeneration protocol of Cymbidium faberi from immature seeds was established. The immature seeds of 50 days old started to form rhizomes 4 months after they were cultured on hormone free medium. The rhizomes multiplied 5 times when subcultured on the medium containing 1.0 mg l–1 -naphthalene acetic acid (NAA) for 40 days and more than 90% of the rhizomes initiated shoots within 60 days on the media containing 0.5 or 1.0 mg l–1 NAA plus 2.0 or 5.0 mg l–1N6-benzylaminopurine (BA). Plantlets were regenerated when the shoots were planted on the basal medium amended with 1 g l–1 activated charcoal for 50 days and the plantlets grew normally after transplanting.  相似文献   

18.
Hairy roots were induced from androgenic embryos of horse chestnut (Aesculus hippocastanum L.) by infection with Agrobacterium rhizogenes strain A4GUS. Single roots were selected according to their morphology in the absence of antibiotic or herbicide resistance markers. Seventy-one putative transformed hairy root lines from independent transformation events were established. Regeneration was induced in MS liquid medium supplemented with 30 6-benzylaminopurine (BA), and the regenerants were multiplied on MS solid medium containing 10 M BA. Following elongation on MS medium supplemented with 1 M BA and 500 mg/l polyvinylpyrrolidone, the shoots were subjected to a root-inducing treatment. Stable integration of TL-DNA within the horse chestnut genome was confirmed by Southern hybridization. The copy number of transgenes was estimated to be from two to four.Communicated by E.D. Earle  相似文献   

19.
A pea rust fungus, Uromyces viciae-fabae, has been classified into two varieties, var. viciae-fabae and var. orobi, based on differences in urediniospore wall thickness and putative host specificity in Japan. In principal component analyses, morphological features of urediniospores and teliospores of 94 rust specimens from Vicia, Lathyrus, and Pisum did not show definite host-specific morphological groups. In molecular analyses, 23 Uromyces specimens from Vicia, Lathyrus, and Pisum formed a single genetic clade based on D1/D2 and ITS regions. Four isolates of U. viciae-fabae from V. cracca and V. unijuga could infect and sporulate on P. sativum. These results suggest that U. viciae-fabae populations on different host plants are not biologically differentiated into groups that can be recognized as varieties.Contribution no. 184, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba, Japan  相似文献   

20.
Recombinant Streptomyces platensis transglutaminase (MtgA) produced by the Streptomyces lividans transformant 25-2 was purified by ammonium sulfate fractionation, followed by CM-Sepharose CL-6B fast flow, and blue-Sepharose fast flow chromatography. The purification factor was ~33.2-fold, and the yield was 65%. The molecular weight of the purified recombinant MtgA was 40.0 KDa as estimated by SDS-PAGE. The optimal pH and the temperature for the enzyme activity were 6.0 and 55 degrees C, respectively, and the enzyme was stable at pH 5.0-6.0 and at temperature 45-55 degrees C. Enzyme activity was not affected by Ca(2+), Li(+), Mn(2+), Na(+), Fe(3+), K(+), Mg(2+), Al(3+), Ba(2+), Co(2+), EDTA, or IAA but was inhibited by Fe(2+), Pb(2+), Zn(2+), Cu(2+), Hg(2+), PCMB, NEM, and PMSF. Optimization of the fermentation medium resulted in a twofold increase of recombinant MtgA activity in both flasks (5.78 U/ml) and 5-l fermenters (5.39 U/ml). Large-scale productions of the recombinant MtgA in a 30-l air-lift fermenter and a 250-l stirred-tank fermenter were fulfilled with maximal activities of 5.36 and 2.54 U/ml, respectively.  相似文献   

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