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1.
Small ; : e2403170, 2024 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-38813750

RESUMO

Constructing I single-atom (ISA) doped CoP electrocatalyst for HER is extremely challenging and has not been reported to date. Herein, an ISA doping-phosphatization strategy is proposed to prepare a novel I single-atom doped P-rich CoPn nanocluster@CoP electrocatalyst (ISA-CoPn/CoP) with enhanced HER performance first. ISA-CoPn/CoP shows a low overpotential of only 44 and 81 mV in 0.5 m H2SO4 solution, to drive a current density of 10 and 100 mA cm-2. ISA and P-rich CoPn nanocluster show unique synergies, which can optimize the H adsorption energy and accelerate the kinetics of HER in the CoP system. The intermediate I─H bond vibration peak is directly observed through in situ Raman testing, demonstrating that ISA doping helps accelerate the HER process. Additionally, the ΔGH of ISA-CoPn/CoP is only 0.05 eV by density functional theory (DFT) calculation, which is conducive to H2 evolution.

2.
Bull Environ Contam Toxicol ; 96(3): 320-5, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26758457

RESUMO

In this study, extracellular polymeric substances of Aphanizomenon flos-aquae (EPS-A) were investigated in order to explore their effect on astrocytes of zebrafish and potential risk for environment. Astrocytes were treated with varying concentrations of EPS-A, the results showed that EPS-A inhibited astrocytes growth in a dose-and time-dependent manner. With the concentrations of EPS-A increasing, the adherent ability of astrocytes decreased and the number of astrocytes floating in the culture medium increased. When treated with 2.35 µg/mL EPS-A, EPS-A induced cell cycle arrest and made the collapse of mitochondrial membrane potential and then led to astrocytes apoptosis. The results suggested that EPS-A could pose a threat to zebrafish and represent risk for environment, so regularly monitoring the presence of EPS-A was very important in nutrient-rich freshwaters when A. flos-aquae blooms broke out.


Assuntos
Aphanizomenon/química , Apoptose/efeitos dos fármacos , Astrócitos/efeitos dos fármacos , Biopolímeros/toxicidade , Água Doce/química , Poluentes Químicos da Água/toxicidade , Peixe-Zebra , Animais , Astrócitos/patologia , Biopolímeros/isolamento & purificação , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Células Cultivadas , Relação Dose-Resposta a Droga , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Fatores de Tempo , Poluentes Químicos da Água/isolamento & purificação
3.
Microb Ecol ; 67(4): 888-96, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24477924

RESUMO

In order to evaluate the self-shading protection for inner photobionts, the photosynthetic activities of three crust lichens were detected using Microscope-Imaging-PAM. The false color images showed that longitudinal photosynthetic gradient was found in both the green algal lichen Placidium sp. and the cyanolichen Peltula sp. In longitudinal direction, all the four chlorophyll fluorescence parameters Fv/Fm, Yield, qP, and rETR gradually decreased with depth in the thalli of both of these two lichens. In Placidium sp., qN values decreased with depth, whereas an opposite trend was found in Peltula sp. However, no such photosynthetic heterogeneity was found in the thalli of Collema sp. in longitudinal direction. Microscope observation showed that photobiont cells are compactly arranged in Placidium sp. and Peltula sp. while loosely distributed in Collema sp. It was considered that the longitudinal photosynthetic heterogeneity was ascribed to the result of gradual decrease of incidence caused by the compact arrangement of photobiont cells in the thalli. The results indicate a good protection from the self-shading for the inner photobionts against high radiation in crust lichens.


Assuntos
Clorofila/metabolismo , Líquens/metabolismo , Fotossíntese , Microbiologia do Solo , China , Clima Desértico , Fluorometria , Especificidade da Espécie
4.
Physiol Plant ; 152(2): 345-54, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24611508

RESUMO

As the dominant cyanobacterial species in biological soil crusts (BSCs), Microcoleus vaginatus often suffer from many stress conditions, such as desiccation and high temperature. In this study, the activities of light-harvesting complexes (LHCs) and reaction centers of photosystem II (PS II) in crust cyanobacteria M. vaginatus were monitored under high temperature and desiccation conditions using chlorophyll fluorescence technology. The results showed that all the fluorescence signals were significantly inhibited by high temperature or desiccation treatments. Under high temperature conditions, it was further demonstrated that PS II reaction centers were first destructed within the first hour, then the LHCs gradually dissociated and free phycocyanin formed within 1-5 h, and the activities of all the light harvesting and reaction center pigment proteins were fully suppressed after 24 h of high temperature treatment. Furthermore, the high temperature treated M. vaginatus lost its ability to recover photosynthetic activity. On the contrary, although desiccation also led to the loss of photosynthetic activity in M. vaginatus, after rehydration in the light the fluorescence parameters including Fo, Fv and Fv/Fm could be well recovered within 12 h. It was concluded that desiccation could provide crust cyanobacteria M. vaginatus some protection from other stresses, such as high temperature demonstrated in this experiment. The combine of temperature change and precipitation pattern in the field provide a guarantee for the alternate metabolism and inactivity in crust cyanobacteria. That may be a very important strategy for the survival of crust cyanobacteria in high temperature regions.


Assuntos
Cianobactérias/fisiologia , Dessecação , Temperatura Alta , Fotossíntese/fisiologia , Clorofila/metabolismo , Espectrometria de Fluorescência , Água
5.
Environ Sci Technol ; 48(1): 307-15, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24303976

RESUMO

Desertification has been recognized as a global environmental problem, and one region experiencing ongoing desertification is the eastern edge of Qubqi Desert (Inner Mongolia). To investigate the facilitating effects of cyanobacterial inoculation technology on the desertification control along this steppe-desert transition region, artificial cyanobacterial crusts were constructed with two filamentous cyanobacteria 3 and 8 years ago combined with Salix planting. The results showed that no crusts formed after 3 years of fixation only with Salix planting, whereas after cyanobacterial inoculation, the crusts formed quickly and gradually succeed to moss crusts. During that course, topsoil environments were gradually improved, providing the necessary material basis for the regeneration of vascular plants. In this investigation, total 27 species of vascular plants had regenerated in the experimental region, mainly belonging to Asteraceae, Poaceae, Chenopodiaceae and Leguminosae. Using space time substitution, the dominant species along with the application of cyanobacterial inoculation technology succeeded from Agriophyllum squarrosum ultimately to Leymus chinensis. In addition, it was found that the shady side of the dunes is more conducive to crust development and succession of vegetation communities. Conclusively, our results indicate artificial cyanobacterial inoculation technology is an effective and desirable path for desertification control.


Assuntos
Conservação dos Recursos Naturais , Cianobactérias , Desenvolvimento Vegetal , China , Clima Desértico
6.
J Colloid Interface Sci ; 656: 68-79, 2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-37984172

RESUMO

In CO2 cycloaddition reactions, hydrogen bond donor (HBD) groups are considered environmentally friendly substitutes for metals to promote epoxide ring-opening through interactions with nucleophilic anions. A core-shell structured ILs-based catalyst (mSiO2@MCM-NH2-OH) with dual hydrogen bond donors (-OH and -NH2) was synthesized by copolymerization strategy. Through in-depth characterization, it has been demonstrated that the catalyst (mSiO2@MCM-NH2-OH) possesses multiple catalytic active sites including -OH, -NH2, Br- groups, and the synergistic effect of double HBD groups (-OH and -NH2) and Lewis base (Br-) significantly improved the catalytic activity. Meanwhile, the core-shell structure of the catalyst effectively prevents the loss of active components, which makes the yield remain at about 94 % after 10 cycles. Based on Density Functional Theory (DFT) calculations, a synergistic catalytic mechanism, which involves dual hydrogen-bond donors (-OH and -NH2) and Lewis bases (Br-) was proposed. The cooperative interaction between -OH/-NH2 and Br- reduced the ring-opening barrier of epoxide from 58.6 to 32.0 kcal mol-1 significantly, and thereby facilitated the CO2 cycloaddition reaction.

7.
Microb Ecol ; 66(2): 394-403, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23389251

RESUMO

Biological soil crusts (BSCs) perform vital ecosystem services, but the difference in biological components or developmental level still affects the rate and type of these services. In order to differentiate crust successional stages in quantity and analyze the relationship between crust developmental level and successional stages, this work determined several biological indicators in a series of different developmental BSCs in the Shapotou region of China. The results showed that crust developmental level (level of development index) can be well indicated by crust biological indicators. Photosynthetic biomass was the most appropriate to differentiate crust successional stages, although both photosynthetic biomass and respiration intensity increased with the development and succession of BSCs. Based on of the different biological compositions, BSCs were quantificationally categorized into different successional stages including cyanobacterial crusts (lichen and moss coverages <20 %), lichen crusts (lichen coverage >20 % but moss coverage <20 %), semi-moss crusts (moss coverage >20 % but <75 %), and moss crusts (moss coverage >75 %). In addition, it was found that cyanobacterial and microalgal biomass first increased as cyanobacterial crusts formed, then decreased when lots of mosses emerged on the crust surface; however nitrogen-fixing cyanobacteria and heterotrophic microbes increased in the later developmental BSCs. The structural adjustment of biological components in the different developmental BSCs may reflect the requirement of crust survival and material transition.


Assuntos
Bactérias/isolamento & purificação , Briófitas/microbiologia , Ecossistema , Fungos/isolamento & purificação , Líquens/microbiologia , Microbiologia do Solo , Solo/química , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Briófitas/metabolismo , Fungos/classificação , Fungos/genética , Líquens/metabolismo , Fotossíntese
8.
Environ Toxicol ; 28(5): 239-54, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-21710505

RESUMO

Aphanizomenon flos-aquae (A. flos-aquae), a cyanobacterium frequently encountered in water blooms worldwide, is source of neurotoxins known as PSPs or aphantoxins that present a major threat to the environment and to human health. Although the molecular mechanism of PSP action is well known, many unresolved questions remain concerning its mechanisms of toxicity. Aphantoxins purified from a natural isolate of A. flos-aquae DC-1 were analyzed by high-performance liquid chromatography (HPLC), the major component toxins were the gonyautoxins1 and 5 (GTX1 and GTX5, 34.04% and 21.28%, respectively) and the neosaxitoxin (neoSTX, 12.77%). The LD50 of the aphantoxin preparation was determined to be 11.33 µg/kg (7.75 µg saxitoxin equivalents (STXeq) per kg) following intraperitoneal injection of zebrafish (Danio rerio). To address the neurotoxicology of the aphantoxin preparation, zebrafish were injected with low and high sublethal doses of A. flos-aquae DC-1 toxins 7.73 and 9.28 µg /kg (5.3 and 6.4 µg STXeq/kg, respectively) and brain tissues were analyzed by electron microscopy and RT-PCR at different timepoints postinjection. Low-dose aphantoxin exposure was associated with chromatin condensation, cell-membrane blebbing, and the appearance of apoptotic bodies. High-dose exposure was associated with cytoplasmic vacuolization, mitochondrial swelling, and expansion of the endoplasmic reticulum. At early timepoints (3 h) many cells exhibited characteristic features of both apoptosis and necrosis. At later timepoints apoptosis appeared to predominate in the low-dose group, whereas necrosis predominated in the high-dose group. RT-PCR revealed that mRNA levels of the apoptosis-related genes encoding p53, Bax, caspase-3, and c-Jun were upregulated after aphantoxin exposure, but there was no evidence of DNA laddering; apoptosis could take place by pathways independent of DNA fragmentation. These results demonstrate that aphantoxin exposure can cause cell death in zebrafish brain tissue, with low doses inducing apoptosis and higher doses inducing necrosis.


Assuntos
Aphanizomenon/metabolismo , Encéfalo/efeitos dos fármacos , Venenos/toxicidade , Toxinas Biológicas/toxicidade , Animais , Aphanizomenon/isolamento & purificação , Apoptose , Proteínas Reguladoras de Apoptose/metabolismo , Toxinas Bacterianas/metabolismo , Toxinas Bacterianas/toxicidade , Encéfalo/metabolismo , Encéfalo/ultraestrutura , Caspase 3/metabolismo , China , Dano ao DNA , Proliferação Nociva de Algas , Humanos , Lagos , Dose Letal Mediana , Masculino , Toxinas Marinhas/metabolismo , Toxinas Marinhas/toxicidade , Necrose , Venenos/metabolismo , Saxitoxina/análogos & derivados , Saxitoxina/metabolismo , Saxitoxina/toxicidade , Toxinas Biológicas/metabolismo , Peixe-Zebra
9.
Front Microbiol ; 13: 848908, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35495652

RESUMO

Archaea exhibit strong community heterogeneity with microhabitat gradients and are a non-negligible part of biocrust's microorganisms. The study on archaeal biogeography in biocrusts could provide new insights for its application in environmental restoration. However, only a few studies on assembly processes and co-occurrence patterns of the archaeal community in patchy biocrusts have been reported, especially considering the number of species pools (SPs). Here, we comprehensively collected biocrusts across 3,500 km of northern China. Different successional biocrusts from various regions contain information of local climate and microenvironments, which can shape multiple unique archaeal SPs. The archaeal community differences in the same successional stage exceeded the variations between successional stages, which was due to the fact that the heterogeneous taxa tended to exchange between unknown patches driven by drift. We also comparatively studied the driving forces of community heterogeneity across three to ten SPs, and assembly and co-occurrence patterns were systematically analyzed. The results revealed that the impact of spatial factors on biogeographic patterns was greater than that of environmental and successional factors and that impact decreased with the number of SPs considered. Meanwhile, community heterogeneity at the phylogenetic facet was more sensitive to these driving factors than the taxonomic facet. Subgroups 1 (SG1) and 2 (SG2) of the archaeal communities in biocrusts were dominated by Nitrososphaeraceae and Haloarchaea, respectively. The former distribution pattern was associated with non-salinity-related variables and primarily assembled by drift, whereas the latter was associated with salinity-related variables and primarily assembled by homogeneous selection. Finally, network analysis indicated that the SG1 network had a higher proportion of competition and key taxa than the SG2 network, but the network of SG2 was more complex. Our study suggested that the development of the archaeal community was not consistent with biocrusts succession. The dominant taxa may determine the patterns of community biogeography, assembly, and co-occurrence.

10.
Microb Ecol ; 62(3): 715-24, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21360138

RESUMO

Although many studies have been conducted on the ecological functions and ecophysiological characteristics of lichen soil crusts (LSCs), no explanation of these results has been provided based on crust structures. Using algae soil crusts (ASCs) as comparison, this work studied the small-scale vertical distribution of algal biomass and stratification in two types of LSCs, by combining the binocular stereomicroscope observations, microscope observations, plate cultures, chlorophyll analysis, and polysaccharides analysis. The results showed an obvious difference in the proportion but not the composition of the algae species between the ASCs and the two LSCs. Approximately 60% and 80% of the total algal biomass were concentrated in the top 1 mm of the soil profile and thalli in the ASCs and LSCs, respectively. This implies that symbiotic algae are the dominant species and primary organic carbon producers in LSCs, and the algal biomass decreased with the depth in both the ASCs and LSCs. The small-scale vertical distributions of the crustal algal biomass and polysaccharides were characterized by obvious successional stage, whereas these were unrelated to the crust type within the successional stage. Additionally, a large amount of fungi, which were always piercing the entire crusts, were observed in the LSCs, but only occasionally in the ASCs. These special structures are purported to cause the LSCs to achieve specific ecological functions, such as higher carbon fixation and greater compressive strength. High biomass, large living space, and advantageous resource utilization privilege suggest that the lichen association is mutualistic and the direction from ASCs to LSCs is developmental.


Assuntos
Biomassa , Líquens/crescimento & desenvolvimento , Microbiologia do Solo , Solo/análise , Clorofila/análise , Clorófitas/crescimento & desenvolvimento , Cianobactérias/crescimento & desenvolvimento , Diatomáceas/crescimento & desenvolvimento , Polissacarídeos/análise
11.
Bioresour Technol ; 238: 602-608, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28482286

RESUMO

Biofilm based microalgal cultivation has recently received great attention because of its low water requirement and harvesting cost. However, the contradiction between microalgal attachment and harvesting still hinders the development of this technology. Therefore, in this study the most readily available and inexpensive shifting sand was used as attached substrate for microalgal (Microcoleus vaginatus) biofilm cultivation under different water conditions. After the inoculation, a stable and easily peeled microalgal biofilm formed through filamentous binding and exopolysaccharide cementing. In general, microalgal biomass, photosynthetic activity and exopolysaccharide accumulation were all significantly affected by the cultivation time, water content and their interaction (P<0.001). According to the maximal photosynthetic activity and microalgal productivity, cultivation time of microalgal biofilm on sand surface should be controlled around 15-25days, with water content at 10%. Based on the biofilm cultivation system, microalgal biomass yield reached up to 11gm-2 eventually on the sand surface.


Assuntos
Biofilmes , Cianobactérias , Microalgas , Biomassa , Fotossíntese
12.
Aquat Toxicol ; 177: 484-93, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27424100

RESUMO

Aphantoxins, neurotoxins or paralytic shellfish poisons (PSPs) generated by Aphanizomenon flos-aquae, are a threat to environmental safety and human health in eutrophic waters worldwide. The molecular mechanisms of neurotoxin function have been studied; however, the effects of these neurotoxins on oxidative stress, ion transport, gas exchange, and branchial ultrastructure in fish gills are not fully understood. Aphantoxins extracted from A. flos-aquae DC-1 were detected by high-performance liquid chromatography. The major ingredients were gonyautoxins 1 and 5 and neosaxitoxin, which comprised 34.04%, 21.28%, and 12.77% of the total, respectively. Zebrafish (Danio rerio) were administered A. flos-aquae DC-1 aphantoxins at 5.3 or 7.61µg saxitoxin equivalents (eq)/kg (low and high doses, respectively) by intraperitoneal injection. The activities of Na(+)-K(+)-ATPase (NKA), carbonic anhydrase (CA), and lactate dehydrogenase (LDH), ultrastructural alterations in chloride and epithelial cells, and reactive oxygen species (ROS) and total antioxidative capacity (T-AOC) were investigated in the gills during the first 24h after exposure. Aphantoxins significantly increased the level of ROS and decreased the T-AOC in zebrafish gills from 3 to 12h post-exposure, suggesting an induction of oxidative stress and inhibition of antioxidant capacity. Reduced activities of NKA and CA demonstrated abnormal ion transport and gas exchange in the gills of aphantoxin-treated fish. Toxin administration also resulted in increased LDH activity and ultrastructural alterations in chloride and epithelial cells, suggesting a disruption of function and structure in zebrafish gills. The observed abnormalities in zebrafish gills occurred in a time- and dose-dependent manner. These findings demonstrate that aphantoxins or PSPs may inhibit ion transport and gas exchange, increase LDH activity, and result in ultrastructural damage to the gills through elevations in oxidative stress and reduced antioxidant capacity. These effects of aphantoxins in the gills of zebrafish suggest an induction of respiratory toxicity. The parameters investigated in this study may be also considered as biomarkers for studying aphantoxin/PSP exposure and cyanobacterial blooms in nature.


Assuntos
Aphanizomenon/metabolismo , Toxinas Bacterianas/toxicidade , Brânquias/efeitos dos fármacos , Toxinas Marinhas/toxicidade , Poluentes da Água/toxicidade , Peixe-Zebra/metabolismo , Animais , Antioxidantes/metabolismo , Anidrases Carbônicas/metabolismo , Cromatografia Líquida de Alta Pressão , Brânquias/metabolismo , Brânquias/ultraestrutura , Humanos , L-Lactato Desidrogenase/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo , Proteínas de Peixe-Zebra/metabolismo
13.
Sci Total Environ ; 538: 492-9, 2015 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-26318686

RESUMO

Biological soil crusts play important ecological functions in arid and semi-arid regions, while different crust successional patterns appeared in different regions. Therefore in this study, the environmental conditions between Shapotou (with cyanobacterial, lichen and moss crusts) and Dalate Banner (with only cyanobacterial and moss crusts) regions of China were compared to investigate why lichen crusts only appeared in Shapotou; at the same time, artificial moss inoculation was conducted to find out the environmental factors promoting crust succession to moss stage. The results showed lichen crusts always developed from cyanobacterial crusts, which provide not only the stable soil surface, but also the biomass basis for lichen formation; furthermore, addition of crust physicochemical characteristics (primarily silt content) play a facilitating effect on lichen emergence (R(2)=0.53). The inoculation experiment demonstrated early crust soil surface and enough water holding content (>4%) provided the essential guarantee for moss germination. Our results show that there is heterogeneity in crust succession in different regions, which may be mainly affected by the ambient soil microenvironments. It is concluded that a positive feedback mechanism is expected between crust succession and ambient soil microenvironments; while a negative feedback mechanism forms between crust succession and free living cyanobacteria and algae.


Assuntos
Briófitas/crescimento & desenvolvimento , Cianobactérias/crescimento & desenvolvimento , Clima Desértico , Ecossistema , Líquens/crescimento & desenvolvimento , Microbiologia do Solo , China , Monitoramento Ambiental , Solo/química
14.
Bioresour Technol ; 182: 144-150, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25689308

RESUMO

Microalgae cultivation has recently been recognized as an important issue to deal with the increasingly prominent resource and environmental problems. In this study, desert cyanobacterium Microcoleus vaginatus was open cultivated in 4 different cultivation conditions in Qubqi Desert, and it was found Chlorella sp., Scenedesmus sp. and Navicula sp. were the main contaminating microalgal species during the cultivation. High light intensity alone was responsible for the green algae contamination, but the accompanied high temperature was beneficial to cyanobacterial growth, and the maximum biomass productivity acquired was 41.3mgL(-1)d(-1). Low temperature was more suitable for contaminating diatoms' growth, although all the microalgae (including the target and contaminating) are still demand for a degree of light intensity, at least average daily light intensity >5µEm(-2)s(-1). As a whole, cultivation time, conditions and their interaction had a significant impact on microalgal photosynthetic activity (Fv/Fm), biomass and exopolysaccharides content (P<0.001).


Assuntos
Cianobactérias/crescimento & desenvolvimento , Biomassa , Biotecnologia/métodos , China , Chlorella/crescimento & desenvolvimento , Cianobactérias/fisiologia , Diatomáceas , Luz , Fotossíntese , Scenedesmus/crescimento & desenvolvimento , Temperatura
15.
J Microbiol ; 52(2): 179-83, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24500483

RESUMO

A study on the effects of light intensity (40 and 80 µE/m(2)/sec) on the components and topographical structures of extracellular polysaccharides (EPS) was carried out in cyanobacteria Nostoc sp.. EPS yield increased with light intensity. However, light intensity did not significantly affect the EPS fractions and monosaccharide composition. Higher light intensity generally resulted in higher protein content of EPS in similar fractions. The topographical structure of EPS, investigated by atomic force microscopy, appeared as spherical lumps, chains and networks. The long chains were observed at higher light intensity. Thus, light intensity affected the yield and nature of EPS.


Assuntos
Nostoc , Polissacarídeos Bacterianos/química , Polissacarídeos Bacterianos/efeitos da radiação , Luz , Microscopia de Força Atômica , Nostoc/química , Nostoc/citologia , Nostoc/efeitos da radiação
16.
Bioresour Technol ; 161: 402-9, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24727701

RESUMO

In order to evaluate the efficiency and potential of salt addition-based two-stage cultivation technology, on the basis of urea as nitrogen source, we compared four types of salts (NaCl, NaHCO3, NaS2O3 and NaAc) as inducers for lipid production in Desmodesmus abundans. The maximum biomass productivity (270.08mgL(-1)d(-1)) was obtained by using 0.25gL(-1) urea. The highest lipid productivity (67.08mgL(-1)d(-1)) and better biodiesel quality were realized by addition of 20gL(-1) NaCl, and the optimal time point for salt addition was determined at 1.79gL(-1) of biomass density. Further cost analysis demonstrated this cultivation process was relatively economical. Above results suggest that NaCl addition is an economical and applicable strategy for lipid enhancement and can be extended for microalgae-based biodiesel production.


Assuntos
Biocombustíveis , Clorófitas/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Microalgas/metabolismo , Cloreto de Sódio/farmacologia , Biomassa , Clorófitas/efeitos dos fármacos , Microalgas/efeitos dos fármacos , Ureia/metabolismo
17.
Huan Jing Ke Xue ; 35(4): 1479-85, 2014 Apr.
Artigo em Zh | MEDLINE | ID: mdl-24946606

RESUMO

Biological soil crusts (BSCs) play important ecological roles in vegetation and ecological restoration in desert regions, and different crust developmental and successional stages have different ecological functions. In this experiment, the BSCs in Shapotou region (at southeast edge of Tengger Desert) were investigated to study crust development and succession through field investigation, microscopic observation combined with quantitative analysis of microbial biomasses. The results showed that BSCs in this region generally developed and succeeded from algal crusts, lichen crusts to moss crusts. With the development and succession of BSCs, crust photosynthetic biomass gradually increased, while microalgal biomass showed a first increasing and then decreasing trend. Among the crust algae (cyanobacteia), Microcoleus vaginatus, as the first dominant species, occupied the most algal biomass and reached a maximum of 0.33 mm3 x g(-1) crusts in algal crusts; while Scytonema javanicum and Nostoc sp. have their maximal biomasses in the later lichen crusts. In addition, it was found that the heterotrophic microbial biomass began to increase in algal crusts, and then decreased in lichen crusts; followed by another increase and the increase achieved the maximum at last in moss crusts. Through the correlation analysis, it was found that bacterial biomass significantly positively correlated with crust organic carbon and Na+ content, while fungal biomass positively correlated with K+ and Na+ content (P < 0.05). In conclusion, this study investigated the developmental and successional patterns of BSCs in Shapotou region, and discussed the effects of crust development and succession on several microbial biomasses from the point of view of environmental adaptation and functional requirement, which may be helpful for us to understand crust development and succession, and provide theoretical and practical significances for crust maintenance and management in ecological restoration of desertification regions.


Assuntos
Biomassa , Microbiologia do Solo , Solo/química , Briófitas/crescimento & desenvolvimento , China , Cianobactérias/crescimento & desenvolvimento , Clima Desértico , Fungos/crescimento & desenvolvimento , Líquens/crescimento & desenvolvimento , Fotossíntese
18.
Huan Jing Ke Xue ; 35(3): 1138-43, 2014 Mar.
Artigo em Zh | MEDLINE | ID: mdl-24881408

RESUMO

In order to understand the improving effects of cyanobacterial inoculation on water retention of topsoil in desert regions, this work focused on the development and succession of biological soil crusts and water holding characteristics of topsoil after cyanobacterial inoculation in Qubqi Desert. The results showed that after the artificial inoculation of desert cyanobacteria, algal crusts were quickly formed, and in some microenvironments direct succession of the algal crusts to moss crusts occurred after 2-3 years. With the development and succession of biological soil crusts, the topsoil biomass, polysaccharides content, crust thickness and porosity increased, while the soil bulk density decreased. At the same time, with crust development and succession, the topsoil texture became finer and the percents of fine soil particles including silt and clay contents increased, while the percents of coarse soil particles (sand content) decreased proportionately. In addition, it was found that with crust development and succession, the water holding capacity and water content of topsoil showed an increasing trend, namely: moss crust > algal crusts > shifting sand. The water content (or water holding capacity) in algal and moss crusts were 1.1-1.3 and 1.8-2.2 times of those in shifting sand, respectively. Correlation analysis showed that the water holding capacity and water content of topsoil were positively correlated with the crust biomass, polysaccharides content, thickness, bulk density, silt and clay content; while negatively correlated with the porosity and sand content. Furthermore, stepwise regression analysis showed that the main factor affecting water content was the clay content, while that affecting water holding capacity was the porosity.


Assuntos
Cianobactérias/crescimento & desenvolvimento , Microbiologia do Solo , Solo/química , Água , Biomassa , Briófitas/crescimento & desenvolvimento , Ecossistema , Dióxido de Silício
19.
Bioresour Technol ; 134: 24-9, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23500555

RESUMO

This study attempted to connect the dots between laboratory research and the outdoors. Chlorella sp. NJ-18 was selected among seven oil-producing algae cultivated in this study because it had the highest lipid productivity. The nitrogen and phosphorus concentrations for cultivating this Chlorella strain were optimized indoors. This strain was incubated outdoors in a 70 L photobioreactor, containing the favorable nitrogen (8.32 mM urea) and phosphorus (0.18 mM monopotassium phosphate) concentrations. Semi-continuous cultivation was performed by harvesting 30 L biomass and replacing it with fresh medium. The maximum biomass and lipid productivity acquired outdoors were 91.84 and 24.05 mg L(-1) d(-1), respectively. Furthermore, biomass productivity could be maintained at a high level throughout the cultivation process when using the semi-continuous mode, whereas it decreased dramatically in batch cultures. More than 95% of the total fatty acids obtained were C16 and C18, which are the main components for biofuel.


Assuntos
Biocombustíveis/microbiologia , Biomassa , Microalgas/metabolismo , Óleos/metabolismo , Técnicas de Cultura Celular por Lotes , Chlorella/efeitos dos fármacos , Chlorella/crescimento & desenvolvimento , Ácidos Graxos/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Lipídeos/química , Microalgas/efeitos dos fármacos , Microalgas/crescimento & desenvolvimento , Nitratos/farmacologia , Nitrogênio/farmacologia , Fósforo/farmacologia , Ureia/farmacologia
20.
Bioresour Technol ; 138: 131-5, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23612171

RESUMO

Chlorella sp. (FACHB-1748) was cultivated outdoors under natural sunlight to evaluate its potential for biofuel production. Urea was selected as nitrogen source, and the concentration was optimized. When the culture reached the late exponential stage, a triggering lipid accumulation test was conducted using different concentrations of sodium chloride and acetate. A scaling-up experiment was also conducted in a 70L photobioreactor. The highest biomass productivity (222.42, 154.48 mg/L/d) and lipid productivity (64.30, 33.69mg/L/d) were obtained with 0.1g/L urea in 5 and 70 L bioreactors, respectively. The highest lipid content (43.25%) and lipid yield (1243.98 mg/L) were acquired with the combination of 10 g/L sodium chloride and acetate. Moreover, the qualities of biodiesel, cetane number, saponification value, iodine value, and cold filter plugging point complied with the standards set by the National Petroleum Agency (ANP255), Standard ASTMD6751, and European Standard (EN 14214).


Assuntos
Biocombustíveis/microbiologia , Biotecnologia/métodos , Chlorella/metabolismo , Microalgas/metabolismo , Acetatos/farmacologia , Biomassa , Biotecnologia/instrumentação , Chlorella/efeitos dos fármacos , Ácidos Graxos/metabolismo , Estudos de Viabilidade , Metabolismo dos Lipídeos/efeitos dos fármacos , Lipídeos/biossíntese , Microalgas/efeitos dos fármacos , Fotobiorreatores/microbiologia , Cloreto de Sódio/farmacologia , Ureia/farmacologia
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