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1.
There is a need for sustainable fuels for diesel engines and fuels containing particles will function as a fuel in diesel engines. Some microalgae such as Chlorella vulgaris are unicellular and 5–10 μm in size, which is suitable for combining in an emulsion fuel. An emulsion consisting of transesterified rapeseed oil, a surfactant and a slurry of C. vulgaris was used as a fuel in an unmodified single cylinder diesel engine. The fuel consumption and emissions of this fuel was determined and although the carbon monoxide levels were higher the NOx emission was lower than that of diesel.  相似文献   

2.
In an agroindustrial wastewater pond, a naturally occurring unicellular microalga, Chlorella vulgaris, was closely associated with the terrestrial plant-associative N2-fixing bacterium Phyllobacterium myrsinacearum. When the two microorganisms were artificially coimmobilized in alginate beads, they shared the same internal bead cavities, and the production of five microalgal pigments increased, but there were no effects on the number of the cells or the biomass of the microalga. The association, however, reduces the ability of C. vulgaris to remove ammonium ions and phosphorus from water. The bacterium produced nitrate from ammonium in synthetic wastewater with or without the presence of the microalga, and fixed nitrogen in two culture media. Our results suggest that interactions between microalgae and associative bacteria should be considered when cultivating microalgae for wastewater treatment.  相似文献   

3.
Using ESR with 5,5-dimethyl-l-pyrroline N-oxide (DMPO) as a spin-trapping reagent, we measured the levels of free radical species generated from living cells of Chlorella vulgaris var. vulgails (IAM C-534). To investigate the production of free radicals in the living Chlorella vulgaris cells, the influence of DMPO toward the intact cells of the Chlorella vulgaris using the O2 evolution rate was first studied as a guide. Since the 02 evolution rate was not changed by DMPO, it was judged that DMPO has no toxicity toward the intact cells of Chlorella vulgaris.

Only hydroxyl radicals (-OH) were detected as the DMPO-OH adduct in the suspension of intact cells of Chlorella vulgaris irradiated with visible light. Moreover, since production of -OH was inhibited by some hydroxyl radical scavengers such as KI and ethanol, production of -OH was proved to be due to hydroxyl radicals. It was also clear that the intensity of OH increased with increasing irradiation intensity of visible light. Therefore, it was suggested that -OH might be one of the photoinhibition factors of the intact Chlorella vulgaris cells in severe light conditions.  相似文献   

4.
通过设置绿球藻(Chlorococcum sphacosum GD)的起始接种浓度(25—400 mg/L), 研究其对水产养殖废水的处理效果及藻细胞的生长特性。研究结果表明, 起始接种浓度为100 mg/L的绿球藻藻液, 其生长特性最佳, 比生长速率最大, 倍增时间最短。随着起始接种浓度的增加, 生长速率逐渐降低, 倍增时间逐渐增加。在起始接种浓度为100 mg/L的条件下, 在5d的培养周期内, 绿球藻能够去除水产养殖废水中96.92%的COD、98.08%的氨氮、98.67%的亚硝氮、91.42%的硝氮及98.36%的总磷。低起始接种浓度(尤其是100 mg/L)有利于绿球藻的生长和污染物降解。研究初步探明了微藻起始接种浓度对水产养殖废水处理效果的影响。通过控制微藻接种浓度有望在提高污染物去除率的同时缩短培养周期并提高容积负荷, 为今后微藻用于大规模水产养殖废水的处理提供了一定的理论支持。  相似文献   

5.
The relationship between O2 and an active oxygen scavenging system in Chlorella vulgaris var.vulgaris (IAM C-534) was investigated. When Chlorella vulgaris was exposed to 2% O2, only traces of active oxygen scavenging enzymes were found. When the Chlorella vulgaris was treated with 20% or 50% O2, it was shown that the level of enzyme activity increased as the O2 concentration increased. An increase in enzyme activity was not found in any specific enzyme but in all of the enzymes, but the level of glutathione and ascorbate remained the same in all the cases. In addition, the photosynthetic efficiency also decreased as the concentration of O2 was increased. These results suggest that an O2 enriched environment can lead to an increase in the production of active oxygen species such as Obullet2 and H2O2 and to a decrease in the photosynthetic efficiency in Chlorella vulgaris. The hydroxyl radical (bulletOH) was detected directly in the Chlorella vulgaris suspension with a spin trapping reagent. It was also clear that the increase in the bulletOH intensity as the visible light intensity increased was unrelated to the O2 concentration. It was suggested that the conditions for producing bulletOH and the other active oxygen species were different, and that two types of oxygen stress should exist in the Chlorella vulgaris.  相似文献   

6.
为研究风车草(Cyperus alternifolius)和香根草(Vetiveria zizanioides)迁移养分的能力,建立17.0m2风车草潜流式人工湿地和13.3 m2香根草潜流式人工湿地处理猪场废水,在四个季节末测定植物生物量和组织氮、磷、铜、锌含量.结果表明,香根草地下部生物量大于风车草,地上部生物量则是风车草大于香根草.风车草年地上部收获量为3406.47 g·m-2,比香根草的1483.88 g·m-2高2.3倍;风车草的氮含量为22.69 mg·g-1,比香根草的15.44 mg·g-1高7.25 mg·g-1;风车草的磷含量为6.09 mg·g-1,比香根草的5.47 mg·g-1高0.62 mg·g-1.植株含铜、锌量风车草略比香根草高.风车草每年迁移N 68.72 g·m-2和P18.49 g·m-2,香根草迁移N 8.93 g·m-2和P 3.69 g·m-2.风车草人工湿地每年由植物迁移的氮、磷、铜、锌比香根草高4~7倍.  相似文献   

7.
The specific growth rate of Chlamydomonas reinhardtii and Chlorella sorokiniana decreased under square-wave light/dark cycles of medium duration, 13–87 s, in comparison to continuous illumination. Three experiments were done in three different turbidostats at saturating and sub-saturating light intensities during the light period, 240–630 μmol m−2 s−1. Within each experiment the light intensity during the light periods of the intermittent light regimes was equal and this intensity was also applied under continuous illumination. The specific growth rate decreased proportional or more than proportional to the fraction of time the algae were exposed to light; this light fraction ranged from 0.32 to 0.88. We conclude that under these light regimes the chlorophyta C. reinhardtii and C. sorokiniana are not able to store light energy in the light period to sustain growth in the dark period at the same rate as under continuous illumination. C. reinhardtii increased its specific light absorbing surface by increasing its chloropyll-a content under light/dark cycles of 13 s duration and a light fraction of 0.67 at 240 μmol m−2 s−1; the chloropyll-a content was twice as high under intermittent illumination in comparison to continuous illumination. The combination of a higher specific light absorption together with a lower specific growth rate led to a decrease of the yield of biomass on light energy under intermittent illumination.  相似文献   

8.
全球气候变化引起内陆水体盐度缓慢升高,对浮游植物造成显著影响。为了探究水体盐度升高对浮游植物生理特性的影响,以普通小球藻为试验对象,在原水和不同盐度(1、3、5 g·L-1)条件下研究普通小球藻生长增殖情况,分析其抗氧化酶活性及对光合作用的生理响应。结果显示,盐度升高会抑制普通小球藻生长,当达到3 g·L-1以上时抑制作用明显,细胞分裂增殖指标均明显下降,叶绿素a合成速率衰减,藻细胞膜损坏严重,同时其光合活性显著降低。这表明过高盐度(>3 g·L-1)极有可能破坏藻细胞的生理结构和抗氧化能力,导致其生长增殖受到抑制。研究结果从细胞增殖和生理特性角度分析了水体盐度变化对水体浮游藻类的影响,以期为保护内陆水体生物多样性提供参考。  相似文献   

9.
1. The curves representing the reciprocal fluorescence yield of chlorophyll a of Photosystem II (PS II) in Chlorella vulgaris as a function of the concentration of m-dinitrobenzene in the states P Q and P Q-, are found to be straight parallel lines; P is the primary donor and Q the primary acceptor of PS II. In the weakly trapping state P Q- the half-quenching of dinitrobenzene is about 0.2 mM, in vitro it is of the order of 10 mM. The fluorescence yield as a function of the concentration of a quencher is described for three models for the structure of pigment systems: the model of separate units, the model of limited energy transfer between the units, and the matrix model. If it is assumed that the rate constant of quenching by dinitrobenzene is high and thus the number of dinitrobenzene molecules per reaction center low, it can be concluded that the pigment system of PS II in C. vulgaris is a matrix of chlorophyll molecules in which the reaction centers are embedded. Theoretical and experimental evidence is consistent with such an assumption.

For Cyanidium caldarium the zero fluorescence yield Ф0 and its quenching by dinitrobenzene were found to be much smaller than the corresponding quantities for C. vulgaris. Nevertheless, our measurements on C. caldarium could be interpreted by the assumption that the essential properties (rate constants, dinitrobenzene quenching) of PS II are the same for these two species belonging to such widely different groups.

2. The measured dinitrobenzene concentrations required for half-quenching in vivo and other observations are explained by (non-rate-limiting) energy transfer between the chlorophyll a molecules of PS II and by the assumptions that dinitrobenzene is approximately distributed at random in the membrane and does not diffuse during excitation.

3. The fluorescence kinetics of C. vulgaris during a 350 ns laser flash of variable intensity could be simulated on a computer using the matrix model. From the observed fluorescence quenching by the carotenoid triplet (CT) and the measurement of the number of CT per reaction center via difference absorption spectroscopy, the rate constant for quenching of CT is calculated to be kT = 3.3 · 1011 s−1 which is almost equal to the rate constant of trapping by an open reaction center (Duysens, L.N.M. (1979) CIBA Foundation Symposium 61 (New Series), pp. 323–340).

4. The fluorescence quenching by CT in non-treated spinach chloroplasts after a 500 ns laser flash (Breton, J., Geacintov, N.E. and Swenberg, C.E. (1979) Biochim. Biophys. Acta 548, 616–635) could be explained within the framework of the matrix model when the value for kT is used as given in point 3.

5. The observations mentioned under point 1 indicate that the fluorescence yield Ф0 for centers in trapping state P Q is probably for a fraction exceeding 0.8 emitted by PS II.  相似文献   


10.
藻类水华频发已成为全球性的水环境问题,近年来,生物控藻法因具有环境友好的特点而备受关注。本研究以我国富营养化湖泊中常见大型底栖动物铜锈环棱螺为操纵生物,通过室内培养试验,研究了其对水华水体中常见蓝藻铜绿微囊藻、绿藻普通小球藻和斜生栅藻生长及光合活性的影响,以期阐明螺-藻间相互作用关系,探究铜锈环棱螺作为生物操纵物种的可行性。结果表明: 铜锈环棱螺能在短时间内大量摄食藻细胞,其对铜绿微囊藻产毒株和不产毒株以及斜生栅藻的去除率均在12 h内达到最大值,分别为73.7%、73.2%和51.1%;其对普通小球藻的摄食强于其他藻类,至试验结束时去除率达到99.2%。产毒铜绿微囊藻产生的微囊藻毒素会在铜锈环棱螺体内累积并促发其肝脏病理学变化,进而阻碍铜锈环棱螺的摄食。试验后期各处理组藻细胞光合活性均显著低于对照组,表明铜锈环棱螺的摄食作用对藻细胞造成了损伤,抑制了其大量增殖。此外,当不产毒铜绿微囊藻与斜生栅藻混合时,铜锈环棱螺的选择摄食性导致微囊藻的优势地位被斜生栅藻所取代。因此,铜锈环棱螺可以通过摄食作用抑制藻类的光合活性并降低其生物量,从而在一定程度上抑制或减缓水华的形成。  相似文献   

11.
The genetic variability and divergence of four species of the genus Crocus L., related to Crocus cartwrightianus group, namely Crocus thomasii Ten., Crocus hadriaticus Herbert, Crocus oreocreticus B.L. Burtt, C. cartwrightianus Herbert, has been studied by means of starch gel isozyme electrophoresis. For each population the following enzymatic loci were analyzed: PGI-1, PGI-2, G6PDH-1, G6PDH-2, IDH-1, IDH-2, 6PGDH-1, 6PGDH-2, SKDH-1, SKDH-2, AK-1 and AK-2. The genetic variability was estimated through the parameters A (mean number of alleles per locus), P (percent of polymorphic loci), Ho (mean observed heterozygosity), and He (mean expected heterozygosity). The genetic differentiation has been assayed by Wrigth's F-statistics, and the genetic divergence by Nei's index. Our data confirmed that the taxa are distinct species, in spite of their similar morphology and karyology. C. thomasii is more genetically similar to C. cartwrightianus and C. oreocreticus than to C. hadriaticus. We hypothesized an autopolyploid origin of saffron, probably from C. cartwrightianus, considering the genotypic classes of Crocus sativus and the other related species of the C. cartwrightianus group studied here.  相似文献   

12.
Two experiments were done to clarify whether or not cell rupture is necessary to improve the digestibility of major components of Chlorella vulgaris: K-5. Chlorella was treated with or without high pressure homogenization (1 × 108 N/m2 at less than −20°C) after a heating process (100-120°C). Chlorella (air-dry matter) contained 934 g dry matter and 244 g essential amino acids (total)/kg. Chemical composition was hardly altered irrespective of the treatment. In the first experiment, pepsin digestibility of chlorella protein was determined in vitro. The cell rupture by high pressure homogenization caused a small but significant improvement in pepsin digestibility of chlorella protein compared with the control. In the second experiment, total tract apparent digestibilities of chlorella were determined in the rat. Digestibility of chlorella protein was significantly enhanced by high pressure homogenization, but the difference (88.6% vs. 87.4%, P < 0.01) due to treatment was small and similar to that observed in the in vitro experiment. These results suggested that Chlorella strain vulgaris: K-5 may be an efficient protein source even without cell rupture.  相似文献   

13.
Explants of the Indo-Pacific sponge Pseudosuberites aff. andrewsi were fed with the microalgae Chlorella sorokiniana and Rhodomonas sp. It was microscopically observed that these algae were ingested and digested by the sponge cells, suggesting that they were consumed by the sponges. The algae were further used for two growth experiments with five explants of P. aff. andrewsi and four explants of P. andrewsi. Growth was measured as the increase in projected body area. The explants showed considerable growth (up to 730% in 54 days for P. aff. andrewsi and up to 680% in 22 days for P. andrewsi), which is much higher than previously reported growth rates for sponges. Growth started after a stationary phase of 5–20 days in which the projected body area did not increase. The growth of P. aff. andrewsi appeared to be linear and was inhibited at the end of the experiment. Two explants of P. andrewsi showed exponential growth instead of linear growth. Hence, no general statements about the growth kinetics of these sponges can be made at this time. However, the high growth rates found in this study suggest a promising future for cultivation of sponges in closed systems.  相似文献   

14.
In the present study, we determined the sequence of group I self-splicing introns found in the large ribosomal RNA subunit of Candida albicans, Candida stellatoidea and the recently-described species Candida dubliniensis. It was found that both the intron and ribosomal RNA nucleotide sequences are almost perfectly identical between different C. albicans strains as well as between C. albicans and C. stellatoidea strains. Comparisons of ribosomal RNA sequences suggest that local isolates of atypical C. albicans from individuals infected with human immunodeficiency virus can be assigned to the C. dubliniensis species. C. dubliniensis strains also harbor a group I intron in their ribosomal RNA, as observed in about 40% of C. albicans strains and all C. stellatoidea strains. This novel C. dubliniensis group I intron is identical to the C. albicans and C. stellatoidea intron, except for two widely divergent stem-loop regions. Despite these differences, the C. dubliniensis intron possesses self-splicing ability in an in vitro assay. Taken together, these data support the idea that C. albicans and C. stellatoidea should be joined together as variants of the same species while C. dubliniensis is a distinct but closely related microorganism. To our knowledge, the C. albicans and C. dubliniensis introns are the first example of a pair of homologous group I introns differing only by the presence of apparently facultative sequences in some stem-loops suspected to be involved in stabilization of tertiary structure.  相似文献   

15.
Reproduction in Chthamalus montagui Southward and Chthamalus stellatus (Poli) has been compared along gradients of wave exposure and tidal height. The proportion of barnacles carrying egg masses was greatest at low shore levels in both species, although the difference between levels was more pronounced in C. stellatus. Both species were found to breed between the beginning of May and the end of September. The mean number of broods released per season in both species ranged from 1.0 to 2.1 at high shore levels, from 2.2 to 3.2 at mid shore levels, and from 2.6 to 4.4 at low shore levels. C. stellatus predominated low on the shore at an intermediately exposed site and on the mid and low shore at the most exposed site. At these places it produced more broods per year than C. montagui. Development of the embryos of the two species was complete after 3 wk in vivo at 15°C. Eggs containing embryos of C. stellatus were larger than those of C. montagui, and within each species, larger barnacles produced larger eggs. Egg masses of C. stellanus included more eggs than those of C. montagui. Brood size in both species was greatest in shelter and least in exposure. Egg production was, however, similar in the two species when adjusted for differences in body mass. Egg production per unit body mass was greatest at an intermediately exposed site.  相似文献   

16.
Yeasts similar to Candida kruisii were isolated repeatedly from the digestive tracts of basidioma-feeding beetles, especially nitidulids inhabiting and feeding on a variety of agarics in the southeastern USA and Barro Colorado Island, Panama. Based on the identical sequences of the D1/D2 domains of the LSU rRNA gene (rDNA) and host beetle information, the isolates were grouped into 19 genotypes which varied from C. kruisii by up to 38 nucleotide differences in the D1/D2 region. Phylogenetic analysis of rDNA sequences and phenotypic traits placed the isolates in C. kruisii and in nine undescribed taxa. The new species and type strains are designated as Candida pallodes (NRRL Y-27653T), C. tritomae (NRRL Y-27650T), C. panamensis (NRRL Y-27657T), C. lycoperdinae (NRRL Y-27658T), C. atbi (NRRL Y-27651T), C. barrocoloradensis (NRRL Y-27934T), C. aglyptinia (NRRL Y-27935T), C. stri (NRRL Y-48063T), and C. gatunensis (NRRL Y-48064T). A phylogeny based on analysis of a combined database of sequences of SSU and LSU rDNA and the ITS region showed that the nine new species formed a novel sister clade to C. kruisii that was strongly supported by bootstrap analysis. Candida pallodes, C. tritomae, C. panamensis, and C. lycoperdinae formed one subclade, while C. atbi, C. barrocoloradensis, C. aglyptinia, C. stri, and C. gatunensis formed a second distinct subclade within the larger clade. Candida pallodes and C. atbi showed a strong host specificity to beetle species in the genus Pallodes (Coleoptera: Nitidulidae) collected from a variety of agarics. On the other hand, C. panamensis, C. tritomae, and C. lycoperdinae were associated with several unrelated beetles in Erotylidae, Scarabaeidae, Tenebrionidae, and Curculionidae as well as Lycoperdina ferruginea (Nitidulidae). Candida pallodes, C. tritomae, C. lycoperdinae, and C. atbi have been isolated repeatedly in the USA, while the other five new species have been found only at Barro Colorado Island, Panama.  相似文献   

17.
The Teloschistaceae is a widespread family with considerable morphological and ecological heterogeneity across genera and species groups. In order to provide a comprehensive molecular phylogeny for this family, phylogenetic analyses were carried out on sequences from the nuclear ribosomal ITS region obtained from 114 individuals that represent virtually all main lineages of Teloschistaceae. Our study confirmed the polyphyly of Caloplaca, Fulgensia and Xanthoria, and revealed that Teloschistes is probably non-monophyletic. We also confirm here that species traditionally included in Caloplaca subgenus Gasparrinia do not form a monophyletic entity. Caloplaca aurantia, C. carphinea and C. saxicola s. str. groups were recovered as monophyletic. The subgenera Caloplaca and Pyrenodesmia were also polyphyletic. In the subgenus Caloplaca, the traditionally recognized C. cerina group was recovered as monophyletic. Because this study is based solely on ITS, to maximize taxon sampling, the inclusion of phylogenetic signal from ambiguously aligned regions in MP (recoded INAASE and arc characters) resulted in the most highly supported phylogenetic reconstruction, compared with Bayesian inference restricted to alignable sites.  相似文献   

18.
Three cultivars differing in their susceptibility to water stress were compared—Phaseolus vulgaris cv. Carioca (susceptible), Vigna unguiculata cv. IT83D (intermediately tolerant) and V. unguiculata cv. EPACE-1 (tolerant)—during an imposed water stress treatment. Variation in leaf gas exchange (i.e. assimilation and stomatal conductance) and leaf relative water content in response to progressive substrate water depletion were investigated. To verify the extent of the injury caused by the drought treatment, leaf gas exchange was measured after rehydration. In the three cultivars, stomatal conductance declined before leaf relative water content was affected. P. vulgaris showed the largest decrease in the rate of stomatal conductance with decreasing substrate water content compared to both V. unguiculata cultivars. Photosynthetic assimilation rates were largely dependent on stomatal aperture, but there was evidence of the participation of non-stomatal factors in the reduction of CO2 fixation. The response of leaf gas exchange parameters to severe water stress conditions differed significantly between P. vulgaris and V. unguiculata cultivars. After rehydration, cultivars can be characterised according to the degree of injury induced by the drought treatment: V. unguiculata cv. EPACE-1 as the least affected, V. unguiculata cv. IT83D slightly affected and P. vulgaris cv. Carioca strongly affected. Similar ranking was obtained with experiments previously performed at a cellular and subcellular level. Our results confirm the utility of physiological parameters as early screening tools for drought resistance in bean cultivars.  相似文献   

19.
G. Dubertret  P. Joliot 《BBA》1974,357(3):399-411
The formation and the organization of Photosystem II photosynthetic units during the greening of a dark-grown Chlorella vulgaris, mutant 5/520, have been investigated by analysing the kinetics of the “activation” of oxygen evolution and of the fluorescence induction.

1. 1. The existence during the early stages of the greening of a stationary photosynthesis demonstrates the presence of active Photosystem II at these initial stages, which are integrated in a functional whole, leading to overall photosynthesis.

2. 2. The rise-time of oxygen evolution has been measured using far-red and green light in order to estimate the relative number of chlorophylls per unit. The amount of chlorophyll a remains relatively constant during the greening, while the progressive addition of chlorophyll b causes the size of the units to increase approx. 2-fold.

3. 3. The induction kinetics of the fluorescence are exponential during the early phases of greening and later become distinctly sigmoidal; this suggests that the first units synthesized on the surface of the membrane are isolated from each other by obstacles preventing electronic excitation transfers and that such obstacles which might correspond to some distance between such units, can disappear at later stages, allowing energy transfers to occur.

These observations suggest that the Photosystem II units represent organized functional entities. They apparently consist of a relatively constant number of chlorophyll a molecules, which during the greening is complemented progressively by the addition of chlorophyll b.  相似文献   


20.
The separation of the main seed proteins from Aquilegia vulgaris and Digitalis purpurea by means of Sephadex G-200 gel filtration and DEAE-Sephadex ion exchange absorption resulted in remarkably similar patterns. Using gel electrophoresis and serological techniques this phenomenon has been attributed to the predominance of two storage proteins present in each taxon: (a) one main protein in Aquilegia (= nigellin) and in Digitalis (= tubiflorin), each, being similar, but probably not homologous. (b) A secondary protein (= aquilegilin) was identified in both taxa. The distribution of only a few storage proteins in Magnoliophytina (angiosperms) with different serological reactivity (= different primary structure) has been presumed, based upon the data obtained.  相似文献   

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