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Microalgal biomasses have been established as promising biosorbents for biosorption to remove heavy metal ions (HMIs) from wastewaters and contaminated natural waterbodies. Understanding the mechanism is important for the development of cost-effective processes for large scale applications. In this paper, a simple mathematical model was proposed for the predication of biosorption capacity of HMI by microalgal cells based on single cell mass, cell size, and HMI radius. One fundamental assumption based on which this model was developed, i.e., the biosorption of HMI by microalgal cells is predominantly monolayer bio-adsorption, was established based on kinetic, isothermal, FTIR, and Pb(II) distribution data generated in this study and in literature. The model was validated using a combination of experimental and literature data as well, demonstrating its capability to provide reasonable estimations although with discrepancies. The biosorption capacities of HMIs (mmol/g) by Chlorella vulgaris were experimentally determined to be in the following order: Pb(II)(0.360)> Zn(II)(0.325)> Cu(II)(0.254)> Ni(II)(0.249)> Cd(II)(0.235)> Co(II)(0.182). We systematically investigated the deviations of the predicted biosorption capacities in term of the effects of a few important parameters that were unaccounted for in the model, including the nanostructures on cell surface, HMI electronegativity, and biosorption buffer pH. Results suggest that the nanostructures on cell wall, likely the hairlike fibers, might be the primary locations where the binding sites for HMI were housed. Furthermore, isothermal data, which is suported by the predictions of this model, indicate the each effective binding site on C. vulgaris cell surface could bind to more than one Co(II) in biosorption while each of the other five HMIs tested in this study required more than one binding sites.
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Chlorella vulgaris , Metais Pesados , Chumbo , Concentração de Íons de Hidrogênio , Metais Pesados/química , Adsorção , Cinética , ÍonsRESUMO
Chondroblastoma is a rare, benign neoplasm of chondroblast cell origin, accounting for less than 1% of primary bone tumors. It is usually diagnosed in the second decade of life with most of the cases involving the long bones such as the femur and humerus. Furthermore, over 90% of cases are in individuals under 30 years of age. In older adults, chondroblastomas are typically found in bones in the foot, such as the talus and calcaneus. Treatment is usually local curettage of the lesion with a relatively low rate of recurrence. In this case report, we present a patient with an atypical age of initial presentation at 49 years, a rare location of the chondroblastoma in the acetabulum, and a recurrence 14 years after surgical resection in the same location. The lesion's radiographic findings of intralesional calcifications alongside the high-signal, heterogeneous composition on T2-weighted MRI were supportive of the atypical diagnosis of chondroblastoma in this patient.
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Venous thoracic outlet syndrome commonly results in arm swelling and pain as the subclavian vein is obstructed within the thoracic inlet. We report the use of ferumoxytol-enhanced contrast MRI in the diagnosis of venous thoracic outlet syndrome in a male adolescent. In this patient who presented with right upper extremity thrombosis, ferumoxytol-enhanced MRI of the chest was able to show both chronic subclavian vein thromboses and dynamic occlusion of the subclavian veins with arm abduction consistent with Paget-Schroetter syndrome.
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Effects of metal ion proprieties and the cell wall structure of green alga Neochloris oleoabundans were investigated on five strategically selected heavy metal ions, Pb(II), Hg(II), Zn(II), Cd(II) and Cu(II). The biosorption of these ions were energy-independent and spontaneous Langmuir adsorption. The adsorption capacities of Pb(II), Hg(II), Zn(II), Cd(II) and Cu(II) were determined to be 1.03, 0.91, 1.20, 0.65 and 1.23 mmol/g, respectively. Data suggest that peptide-containing molecules and non-cellulosic polysaccharides on cell wall were the primary sites of adsorption. Ion Pb(II) showed the strongest inhibitive effects on the adsorption of other metal ions on cells in binaries, corresponding to its large affinity to the biosorbents, which was next only to that of Cu(II). A linear relation was established for the first time between the adsorption capacity and the impact factor, which is defined in this paper as the electronegativity of a metal ion normalized by its atomic radius. In other words, adsorption capacity of N. oleoabundans biomass to the tested two-valence metal ions is proportional to the electronegativity and inversely proportional to the radius of the metal ions. Cell aggregation was caused by the addition of Cu(II), which exhibited distinctive adsorption behaviors than other metal ions.
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Clorófitas , Metais Pesados , Parede Celular , Concentração de Íons de Hidrogênio , ÍonsRESUMO
PURPOSE: To determine if CT features of adrenal nodules and of the remainder of the abdomen can predict autonomous cortisol secretion (ACH) in patients with adrenal nodules, and to identify a nodule size threshold below which ACH is unlikely. METHODS: Retrospective review of adult patients with adrenal nodules who underwent CT of abdomen and 1-mg Dexamethasone suppression test within 1 year of each other. Patients were considered to have no ACH if serum cortisol was ≤ 1.8 µg/dL after the 1-mg dexamethasone suppression test and to have possible or definite autonomous cortisol secretion if serum cortisol was > 1.8 µg/dL. The following CT features were assessed: Adrenal nodule length, nodule width, unenhanced nodule attenuation, contralateral adrenal gland thickness, visceral and subcutaneous adipose tissue area, skeletal muscle area and density, and unenhanced liver attenuation. RESULTS: 29 patients had no autonomous cortisol secretion and 29 patients had possible or definite autonomous cortisol secretion. Nodule length and width were the only two variables that significantly differed between patients with nonfunctional nodules and those with possibly or definitely functional nodules. Using a threshold nodule length of 1.5 cm, the sensitivity and specificity for predicting possible or definite autonomous cortisol secretion was 93.1% and 37.9%, respectively. CONCLUSION: Autonomous cortisol secretion in patients with adrenal nodules correlates with increasing nodule size. A nodule length threshold of 1.5 cm provides 93.1% sensitivity for predicting possible or definite ACH based on the 1-mg Dexamethasone suppression test.
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Neoplasias das Glândulas Suprarrenais , Hidrocortisona , Abdome , Neoplasias das Glândulas Suprarrenais/diagnóstico por imagem , Adulto , Humanos , Estudos Retrospectivos , Tomografia Computadorizada por Raios XRESUMO
Plastic litters have become the predominant components of marine debris due to extensive consumption plastics and mismanagement of plastic wastes. As part of the problem, microplastics (MPs) and nanoplastics (NPs) have generated special concerns due to their unique features that make them easy to transfer among oceans in the marine ecosystem, across different trophic levels inside the food web, and even across different tissues inside contaminated animals. Studies have demonstrated the almost omnipresence of MPs in the marine ecosystem, which present serious threats to the health of marine animals, causing symptoms such as malnutrition, inflammation, chemical poisoning, growth thwarting, decrease of fecundity, and death due to damages at individual, organ, tissue, cell, and molecule levels. The information on NPs in the marine ecosystem has been scarce due to the challenges in sampling and detecting these nano-scaled entities. In vitro and in vivo experiments have demonstrated that NPs have the potential to penetrate different biological barriers including the gastrointestinal barrier and the brain blood barrier and have been detected in many important organs such as brains, the circulation system and livers of sampled animals.
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Monitoramento Ambiental , Plásticos/análise , Poluentes Químicos da Água/análise , Ecossistema , Cadeia Alimentar , Oceanos e Mares , ResíduosRESUMO
The last decade has witnessed significant developments in the biosynthesis of noble metal nanoparticles (NMNPs) due to their distinct advantages in various practical applications. Many photosynthetic organisms, including plants, microalgae, and photosynthetic bacteria, have been explored for NMNP synthesis in an eco-friendly and cost-effective manner. These biomasses were used for NMNP biosynthesis as growing cells, non-growing cells, whole cells extract, disrupted cell extract, residual biomasses, gum solutions, etc. Different mechanisms might be involved to reduce noble metal ions to NMNP. These mechanisms include reduction of metal ions catalysed by reductases using NADH as electron donors, reduction of metal ions using biochemical molecules such as polysaccharides and proteins as electron donators, and light-dependant biosynthesis of NMNP involving pigments for light capture and water-splitting for electron supplementation. NMNP may be applied as catalyst, antibacterial, anticancer, and drug delivery vehicle.
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Bactérias/metabolismo , Nanopartículas Metálicas/química , Microalgas/metabolismo , Fotossíntese , Plantas/metabolismo , Bactérias/química , Microalgas/química , Tamanho da Partícula , Plantas/química , Propriedades de SuperfícieRESUMO
The purification process of wastewater containing heavy metal ions (HMIs) using nano-fibrous metal-organic frameworks, MOF-808, embedded polyacrylonitrile membrane has been studied. The process parameters that were evaluated included feed concentration, transmembrane pressure (TMP), and membrane thickness. The effect of coexisting cations in the solution upon the removal efficiencies of Zn2+, Cd2+, Pb2+ and Hg2+ ions was also investigated. Results from the filtration experiments indicate a substantial variation in the feed volume that the membrane can treat before the permeate lead concentration reaches the allowable limit of 10â¯ppb, depending on the process parameter. An increase in the membrane thickness showed a significant improvement (26%) with 440â¯L of the treated feed volume after doubling the membrane layer. An increase in TMP could reduce the treated feed volume by 38% while a decrease in feed concentration led to a 21% increase in the treated feed volume. In the presence of other common background cations in the solution, the removal efficiency of HMIs by adsorption onto MOF-808 dropped by 18 to 37%. This result was dependent upon the HMIs, in the presence of up to three other cations but was minimal in the presence of a single cation indicative of good selectivity.
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Silver nanoparticles (AgNPs) were synthesized by incubating the mixture of AgNO3 solution and whole-cell aqueous extracts (WCAEs) of Neochloris oleoabundans under light conditions. By conducting single-factor and multi-factor optimization, the effects of parameters including AgNO3 concentration, pH, and extraction time were quantitatively evaluated. The optimal conditions in terms of AgNP yield were found to be 0.8 mM AgNO3, pH 5, and 9-h extraction. The AgNPs thus synthesized were quasi-spherical with a mean particle diameter of 16.63 nm and exhibited decent uniformity as well as antibacterial activities, which may facilitate AgNP biosynthesis's application in the near future.
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Antibacterianos/isolamento & purificação , Extratos Celulares , Clorófitas/metabolismo , Luz , Nanopartículas Metálicas/química , Prata/metabolismo , Extratos Celulares/química , Extratos Celulares/efeitos da radiação , Clorófitas/citologia , Clorófitas/efeitos da radiação , Tamanho da Partícula , Prata/química , Prata/isolamento & purificação , Propriedades de SuperfícieRESUMO
BACKGROUND: Low concentration NaHCO3 (ca. 12 mM) had been demonstrated to be an excellent carbon source for industrially important green alga Chlorella vulgaris and high concentration NaHCO3 (e.g. 160 mM) had been shown to be capable of controlling protozoa and stimulating lipid accumulation of another green alga, i.e., Neochloris oleoabundans. Furthermore, little was known about the mechanisms of the effects of NaHCO3 on microalgae. Thorough studies on the effects of high NaHCO3 on C. vulgaris and their mechanisms were therefore warranted. METHODS: We systematically compared the cell growth, lipid production, and cell morphology of the industrially important C. vulgaris in 160 mM NaHCO3 or 160 mM NaCl media at different pH levels. These data allowed us to analyze the effects of total dissolved inorganic carbon (DIC) and individual DIC species on C. vulgaris. Cell growth of C. vulgaris at a range of concentrations at 160 mM or lower was also studied. RESULTS: Cellular lipid cell content of 494 mg g-1 and lipid productivity of 44.5 mg L-1 day-1 were obtained at 160 mM NaHCO3 and pH 9.5. High concentration NaHCO3 (e.g. 160 mM) was inhibitive to cell growth but stimulating to lipid accumulation and caused unicellular C. vulgaris to transfer to colonial cells. Increasing pH in the range of 7.5-9.5 caused increasing inhibition to cell growth in 160 mM NaCl. Whereas the optimal pH for cell growth was 8.5 for 160 mM NaHCO3 cultures. Comparative experiments with 0-160 mM NaHCO3 indicate that 10 mM was the optimal concentration and increasing NaHCO3 from 10 to 160 mM caused increasing inhibition to cell growth. CONCLUSIONS: High concentration DIC was inhibitor to cell growth but stimulator to lipid accumulation of C. vulgaris. It caused unicellular C. vulgaris to transform to colonial cells. Results suggest that high concentration of a particular DIC species, i.e., dCO2, was the primary stress responsible for cell growth inhibition. Where CO32- was likely the DIC species responsible for lipid stimulation of C. vulgaris. Furthermore, we propose that the colony formation at high DIC conditions was employed by C. vulgaris to mitigate the stress by minimizing cell exposure to unfavorable environment.
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Chlorella vulgaris/efeitos dos fármacos , Chlorella vulgaris/crescimento & desenvolvimento , Lipídeos/biossíntese , Bicarbonato de Sódio/farmacologia , Biocombustíveis , Biomassa , Carbono/análise , Chlorella vulgaris/metabolismo , Meios de Cultura/análise , Meios de Cultura/química , Concentração de Íons de HidrogênioRESUMO
Insulin production by the pancreatic ß cell is critical for the glucose homeostasis of the whole organism. Although the transcription factors required for insulin production are known, the upstream pathways that control insulin production are less clear. To further elucidate this regulatory network, we created a genetic interaction map of insulin production by performing â¼20,000 pairwise RNA interference knockdowns of insulin promoter regulators. Our map correctly predicted known physical complexes in the electron transport chain and a role for Spry2 in the unfolded protein response. To further validate our map, we used it to predict the function of an unannotated gene encoding a 37-kDa protein with no identifiable domains we have termed mitochondrial fission factor interactor (Mfi). We have shown that Mfi is a binding partner of the mitochondrial fission factor and that Mfi inhibits dynamin-like protein 1 recruitment to mitochondria. Our data provide a resource to understand the regulatory network of insulin promoter activity.
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Células Secretoras de Insulina/metabolismo , Insulina/biossíntese , Mitocôndrias/metabolismo , Dinâmica Mitocondrial/genética , Animais , Linhagem Celular , Dinaminas , GTP Fosfo-Hidrolases , Redes Reguladoras de Genes , Humanos , Insulina/genética , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas de Membrana/metabolismo , Camundongos , Proteínas Associadas aos Microtúbulos , Proteínas Mitocondriais/metabolismo , Regiões Promotoras Genéticas/genética , Resposta a Proteínas não DobradasRESUMO
This study investigated the role of chlorophyll and light in the biosynthesis of silver nanoparticles (AgNPs) using disrupted cell aqueous extract of Neochloris oleoabundans. It was found that, while increasing sonication time increased the percentage of disrupted cells and efficiency of aqueous cell extraction, over-sonication reduced AgNPs production. AgNPs biosynthesis required illumination of white, blue, or purple light while AgNPs formation was undetectable under dark condition or illumination of orange or red light, indicating only photons of high energy levels among the photosynthetic active radiations are capable of exciting the electrons of chlorophylls to a state that is sufficient for Ag+ reduction. Chlorophylls were demonstrated to be an essential component mediating the reduction of Ag+ and results of mass balance suggest that chlorophylls need to be recycled for the reaction to complete. The ultimate electron donor was hypothesized to be water, which supplemented electrons through water splitting catalyzed by photosynthetic enzyme complexes such as photosystem II. A hypothetical reaction mechanism is proposed for the light-dependent biosynthesis of AgNPs based on systematic experimental results and literature data for the first time.
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Extratos Celulares/química , Extratos Celulares/efeitos da radiação , Clorófitas/citologia , Clorófitas/metabolismo , Luz , Nanopartículas Metálicas/química , Prata/metabolismo , Clorófitas/efeitos da radiação , Tamanho da Partícula , Fotossíntese/efeitos da radiação , Prata/química , Prata/isolamento & purificação , Propriedades de SuperfícieRESUMO
Electrospun nanofiber composite membranes containing water-stable metal-organic frameworks (MOFs) particles (Zr-based MOF-808) supported on polyacrylonitrile (PAN) nanofiber synthesized via co-electrospinning have been prepared. MOF particles were dispersed in the organic polymer, and their subsequent presence was inferred by scanning electron microscopy. Membrane performance in heavy metal ion adsorption in batch filtration was evaluated on the basis of Cd2+ and Zn2+ ions sequestration. The adsorption capacities of the pristine MOF and the MOF composite membrane revealed that MOF particles in the membrane could be accessed for adsorption in the hydrophilic PAN membranes. The maximum adsorption capacities were 225.05 and 287.06 mg g-1 for Cd2+ and Zn2+, respectively. Conventional thermal activation of pristine MOF and composite membrane revealed a crystal downsizing, while "hydractivation" produced an expanded MOF with enhanced adsorption potentials. The PAN/MOF-808 "hydractivated" composite membrane could treat 580 mL of Cd, whereas the conventional vacuum-activated composite treated 464 mL. The high separation performance and reusability of the membranes and the outstanding water stability of the MOFs suggested the developed membrane as a potential candidate for water treatment.
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Among other applications, metal-organic frameworks (MOFs) are slowly gaining grounds as fillers for desalination composite membranes. In this study, superhydrophobic poly(vinylidene fluoride) nanofibrous membranes were fabricated with MOF (iron 1,3,5-benzenetricarboxylate) loading of up to 5 wt % via electrospinning on a nonwoven substrate. To improve the attachment of nanofibers onto the substrate, a substrate pretreatment method called "solvent basing" was employed. The iron content in the nanofiber, measured by energy-dispersive X-ray spectroscopy, increased proportionally with the increase of the MOF concentration in the spinning dope, indicating a uniform distribution of MOF in the nanofiber. The water contact angle increased up to 138.06 ± 2.18° upon the incorporation of 5 wt % MOF, and a liquid entry pressure of 82.73 kPa could be maintained, making the membrane useful for direct contact membrane distillation experiments. The membrane was stable for the entire operating period of 5 h, exhibiting 2.87 kg/m2·h of water vapor flux and 99.99% NaCl (35 g/L) rejection when the feed and permeate temperature were 48 and 16 °C, respectively. Immobilization of MOF on nanofibers with the enhanced attachment was proven by inductively coupled mass spectrometry analysis, by which no Fe2+ could be found in the permeate to the detection limit of ppt.
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Cultivation of microalgae requires consideration of shear stress, which is generated by operations such as mixing, circulation, aeration and pumping that are designed to facilitate mass and heat transfer as well as light distribution in cultures. Excessive shear stress can cause increased cell mortality, decreased growth rate and cell viability, or even cell lysis. This review examines the sources of shear stress in different cultivation systems, shear stress tolerance of different microalgal species and the physiological factors and environmental conditions that may affect shear sensitivity, and potential approaches to mitigate the detrimental effects of shear stress. In general, green algae have the greatest tolerance to shear stress, followed by cyanobacteria, haptophytes, red algae, and diatoms, with dinoflagellates comprising the most shear-sensitive species. The shear-sensitivity of microalgae is determined primarily by cell wall strength, cell morphology and the presence of flagella. Turbulence, eddy size, and viscosity are the most prominent parameters affecting shear stress to microalgal cells during cultivation.
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Microalgas , Estresse Mecânico , Reatores Biológicos , Cianobactérias , Dinoflagellida , Microalgas/citologia , Microalgas/fisiologiaRESUMO
Cell density and morphology changes were tested to examine the effects of salts including NaHCO3 , NaCl, KHCO3 , and KCl at 160 mM on protozoa. It was demonstrated that ionic stress rather than osmotic stress led to protozoa cell death and NaHCO3 was shown to be the most effective inhibitor. Deformation of cells and cell shrinkage were observed when protozoan cells were exposed to polyethylene glycol (PEG) or any of the salts. However, while PEG treated cells could fully recover in both number and size, only a small portion of the salt-treated cells survive and cell size was 36-58% smaller than the regular. The disappearance of salt-treated protozoa cells was hypothetically attributed to disruption of the cytoplasmic membrane of these cells. It is further hypothesized that the PEG-treated protozoan cells carried out regulatory volume increase (RVI) after the osmotic shock but the RVI of salt-treated protozoa was hurdled to varied extents. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1418-1424, 2017.
Assuntos
Amoeba/efeitos dos fármacos , Incrustação Biológica/prevenção & controle , Clorófitas/fisiologia , Cilióforos/efeitos dos fármacos , Pressão Osmótica/efeitos dos fármacos , Sais/farmacologia , Amoeba/citologia , Amoeba/fisiologia , Técnicas de Cultura de Células/normas , Proliferação de Células/efeitos dos fármacos , Forma Celular/efeitos dos fármacos , Clorófitas/citologia , Cilióforos/citologia , Cilióforos/fisiologia , Concentração Osmolar , Polietilenoglicóis/farmacologiaRESUMO
A novel hydrophobic membrane-based desiccant fiber (MDF) was developed by loading lithium chloride into hydrophobic hollow fiber membranes. The MDF thus made was then tested for vapor absorption under controlled conditions. Furthermore, an MDF pad, which was made by weaving MDF into a piece of garment, was built into a laboratory vacuum desiccant cooling (VDC) setup, which included the MDF pad as the desiccant layer and a cooling towel saturated with water as the water reservoir, to test the cooling effects at atmospheric pressure and vacuum of 25 in. of Hg. Results indicate that MDF is suitable for applications such as in VDC. Mass and heat transfer of vapor absorption by MDF were also analyzed.
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This study evaluated long-term non-sterile cultivation of freshwater green alga Neochloris oleoabundans in a 15-liter bubble column photobioreactor (BCPBR) and the effects of a membrane-based localized oxygen remover (LOR) on deoxygenation, cell growth, and lipid production of N. oleoabundans. Batch and continuous cultivations were carried out under non-sterile conditions for 53 days with no detectable protozoa or other biological contaminants, indicating successful long-term contamination-free cultivation. The results show that the BCPBR equipped with LOR (BCPBR-LOR) has enhanced deoxygenation efficiency and were able to maintain dissolved oxygen at a level of around 120% air saturation, which was 32% lower than that of the conventional BCPBR, which had no LOR. While similar biomass concentration and productivity were obtained in both systems, significantly higher lipid cell content and lipid productivity of microalgae were obtained in the latter, which was attributed to the low dO2 in culture due to enhanced deoxygenation efficiency of BCPBR-LOR.
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Clorófitas/crescimento & desenvolvimento , Oxigênio/isolamento & purificação , Fotobiorreatores/microbiologia , Biomassa , Clorófitas/metabolismo , Concentração de Íons de Hidrogênio , Lipídeos/análise , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , Pigmentos Biológicos/metabolismo , Solubilidade , Temperatura , Fatores de TempoRESUMO
Membrane distillation (MD) is a promising separation technique capable of being used in the desalination of marine and brackish water. Poly(vinylidene fluoride) (PVDF) flat sheet nano-composite membranes were surface modified by coating with electro-spun PVDF nano-fibres to increase the surface hydrophobicity. For this purpose, the nano-composite membrane containing 7 wt.% superhydrophobic SiO2 nano-particles, which showed the highest flux in our previous work, was first subjected to pore size augmentation by increasing the concentration of the pore forming agent (Di-ionized water). Then, the prepared flat sheet membranes were subjected to nanofibres coating by electro-spinning. The uncoated and coated composite fabricated membranes were characterized using contact angle, liquid entry pressure of water, and scanning electron microscopy. The membranes were further tested for 6 h desalination by direct contact membrane distillation (DCMD) and vacuum membrane distillation (VMD), with a 3.5 wt.% synthetic NaClaq as the feed. In DCMD the feed liquid and permeate side temperature were maintained at 27.5 °C and 15 °C, respectively. For VMD, the feed liquid temperature was 27 °C and a vacuum of 94.8 kPa was applied on the permeate side. The maximum permeate flux achieved was 3.2 kg/m(2).h for VMD and 6.5 kg/m(2).h for DCMD. The salt rejection obtained was higher than 99.98%. The coated membranes showed a more stable flux than the uncoated membranes indicating that the double layered membranes have great potential in solving the pore wetting problem in MD.
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Destilação/instrumentação , Membranas Artificiais , Nanocompostos , Nanofibras , Polivinil , Dióxido de Silício/química , Purificação da Água/métodos , Água/química , Destilação/métodos , Cloreto de Sódio/químicaRESUMO
Combined effects of pH (i.e., 7.5, 8.5, and 9.5) and bicarbonate (i.e., 0, 80 and 160mM NaHCO3) on lipid accumulation and on biological contaminant viability in a protozoa-contaminated culture of the freshwater microalga Neochloris oleoabundans were studied. Cultures grown in the media containing 160mM NaHCO3 at pH 9.5 obtained the highest biomass concentration (DCWmax=1.32g/L), lipid content (LC=327mg/g), which corresponded to a lipid productivity of 56mg/(L·d), and the culture was protozoa free one day after inoculation. Other cultures, 160mM NaHCO3 at pH 8.5 (DCWmax=1.32g/L, LC=223mg/g), and 80mM NaHCO3 at pH 9.5 (DCWmax=1.25g/L, LC=264mg/g) could delay protozoan growth, but not inhibit it completely. These results suggest 160mM NaHCO3 or slightly above at pH levels of 8.5-9.5 may be used in outdoor cultivation processes of freshwater N. oleoabundans to control protozoa contamination while maintain a high lipid content.