Competition and succession between the oily alga Botryococcus braunii and two green algae Chlorella vulgaris and Chlamydomonas reinhardtii

Contamination by other algal species is a major problem in the culture of the oil-producing green alga Botryococcus braunii (Bb). In this study, the population interactions between Bb and two small green algae, Chlorella vulgaris (Cv) and Chlamydomonas reinhardtii (Cr), were separately investigated in two controlled experiments. Filtrates of Cv or Cr significantly stimulated the growth of Bb in the first 9–11 days when the filtrates were derived from a low- or medium-density algal culture. However, filtrates of Cv and Cr from the high-cell-density cultures significantly inhibited Bb growth from day 11 and 7, respectively. In Bb–Cv competition, the growth of Bb was significantly inhibited by Cv at the biomass ratio of Bb/Cv?=?1:1. However, when the Cv component reduced to 0.5 (Bb/Cv?=?1:0.5) or 0.25 (Bb/Cv?=?1:0.25), the growth of Bb was faster than that in the control in the first 13 days. Similarly, in Bb–Cr competition, the biomass ratios of 1:0.5 and 1:0.25 (Bb/Cr) favoured the growth of B. braunii in the first 15 days, but the growth of Bb decreased in the Bb/Cr ratio of 1:1 from day 15. By contrast, the growth of Cv and Cr were not affected by the presence of Bb in all biomass ratios. These results suggest that Cv and Cr could impact the growth of Bb by metabolites in the culture medium, and when the biomass of Bb is two to four times that of other algae, this oily alga becomes competitive over other algal species. This study reveals the mechanism of population dynamics of this oily alga competing with small and fast-growing algae. The results are applicable in reducing algal competition and regulating species succession between slow and fast-growing algae species.     

A carbon budget for heterotrophically grownAnkistrodesmus braunii andChlorella vulgaris

Summary Heterotrophic and photoheterotrophic growth of the green algaeChlorella vulgaris andAnkistrodesmus braunii were examined and compared through growth measurements and mass carbon budgets. Using two different estimates of overall efficiency, based upon the ratios of CO₂ evolved to substrate taken up and cellular carbon to substrate carbon utilized, it was concluded that both micro-organisms were capable of photoheterotrophy althoughC. vulgaris was more efficient thanA. braunii. Mass carbon budgets showed the distribution of carbon. After 11 days of growth in the light, 97 and 76% of the glucose substrate was accounted for as cell biomass forC. vulgaris andA. braunii respectively. Fermentation pathways appeared to function in both micro-organisms, particularly in the dark and in ageing cultures, as indicated by the apparent loss of carbon as volatile organics. The results obtained with the two micro-organisms studied demonstrate the ability of green algae to photoheterotrophically and heterotrophically convert a high proportion of an organic substrate into biomass. Thus, high-rate oxidation ponds should be considered from a heterotrophic perspective with a view to exploiting this heterotrophic potential.

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Un presupuesto para el carbono en el crecimiento heterótrofo de Ankistrodesmus braunii y Chlorella vulgaris

Resumen Se examinó y comparó el crecimiento heterótrofo y fotoheterótrofo midiendo crecimiento y presupuestos para el carbono de las siguientes algas verdes:Chlorella vulgaris y Ankistrodesmus braunii. La eficiencia general se estimó mediante dos parámetros: el cociente entre CO₂ suministrado y CO₂ fijado por el sustrato, y el cociente entre carbono celular y carbono del sustrato utilizado. Apartir de estas medidas se concluyó que ambos micro-organismos eran capaces de fotoheterotrofia aunqueC. vulgaris era más eficiente queA. braunii. Los presupuestos para la masa carbonada mostraron la distribución del carbono. Después de 11 días de crecimiento en presencia de luz el 97 y el 76% de la glucosa del sustrato se había transformado en biomasa celular enC. vulgaris y enA. braunii respectivamente. En ambos microorganismos parecieron funcionar vías fermentativas, especialmente en la oscuridad y en cultivos viejos, como se vio indicado por la aparente pérdida de carbono en formo de compuestos orgánicos volátiles. Los resultados obtenidos demuestran la habilidad de las algas verdes para convertir tanto fotoheterótrofa como heterótroficamente una elevada proporción de sustratos orgánicos en biomasa. Las balsas con una elevada demanda de oxigeno deberian, pues, de ser consideradas bajo una perspectiva heterótrofa con vistas a la explotación de dicho potencial heterótrofo.

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Bilans carbonés d'Ankistrodesmus braunii et de Chlorella vulgaris en croissance hétérotrophe

Résumé Les croissances hétérotrophes et photohétérotrophes des algues vertesChlorella vulgaris etAnkistrodesmus braunii ont été étudiées comparativement en mesurant la croissance et en établissant des bilans carbonés. A partir de deux estimations distinctes de l'efficacité globale, consistant dans les rapports CO₂ produit sur substrat utilisé et carbone cellulaire sur carbone métabolisé, il a été conclu que les deux micro-organismes sont photo-hétérotrophes, mais queC. vulgaris est plus efficace queA. braunii. La distribution du carbone a été déterminée par les bilans carbonés. Après onze jours de croissance à la lumière, les quantités de substrat carboné retrouvées dans la biomasse cellulaire deC. vulgaris et deA. braunii sont respectivement de 97 et 76%. Les voies fermentatives paraissent être présentes chez les deux microorganismes, et cela surtout à l'obscurité et dans les vieilles cultures, comme l'indique la perte apparente de carbone sous forme de composés organiques volatils. Les résultats obtenus avec les deux micro-organismes étudiés démontrent que les algues vertes sont capables de convertir photo-hétérotrophiquement et hétérotrophiquement une proportion élevée de la matière organique en biomasse. De ce fait, les étangs à taux d'oxydation élevée devraient être considérés du point de vue de l'exploitation de leur potentiel hétérotrophe.

     

Spectroscopic investigations of U(VI) species sorbed by the green algae Chlorella vulgaris

The green alga Chlorella vulgaris has the ability to bind high amounts of uranium(VI) in the pH range from 3 to 6. At pH 3 up to 40% of the uranium are bound by the algal cells. The uranium removal is almost complete at pH 5 and 6 under the given experimental conditions. Scanning electron microscopy and laser-induced fluorescence spectroscopy were used to characterize uranyl species formed in the selected pH range. The micrographs show a regular distribution of U(VI) on the cell surface. Fluorescence spectroscopic investigations of formed algal uranyl complexes indicate that the binding of U(VI) to carboxyl groups plays a dominating role at pH 3, whereas a minor impact of organic phosphate compounds on the U(VI) sorption cannot be excluded. In contrast, at pH 5 and 6 the phosphate groups are mainly responsible for the removal and binding of U(VI) by formation of organic and/or inorganic uranyl phosphates.     

Augmentation of antitumor resistance by a strain of unicellular green algae,Chlorella vulgaris

Summary Growth of Meth-A tumor in CDF1 mice was inhibited significantly by injection of a hot water extract of a strain of Chlorella vulgaris (CE) into the tumor or into the subcutaneous tissue near the tumor. The augmentation of resistance by CE may require the participation of T cells and macrophages, since it was abolished or reduced in athymic nude mice or mice treated with carrageenan, a macrophage blocker. Mice treated with CE exhibited antigen-specific augmented resistance against rechallenge with tumor. Moreover, the antitumor effect of CE was comparable with that of Corynebacterium parvum, but its mechanism of effect might be different.     

PP333用于藻类培养影响异养小球藻的生长及蛋白质含量

用植物生长物质PS333处理异养小球藻,研究了PP333对异养小球藻的生长及蛋白质含量的影响,实验结果表明,PP333能抑制异养小球藻的生长,同时也能显著提高小球藻的蛋白质含量,选取适当浓度的PP333处理异养小球藻可达到小球藻的细胞密度较高,其蛋白质含量又接近自养水平的目的。用50mg/L PP333处理异养小球藻,摇瓶批次培养时,小球藻的蛋白质含量与生物量分别为47.88%和3.60g/L,而对照的分别为37.34%和4.21g/L,摇瓶分批流加培养时,小球藻的蛋白质含量与生物量分别为50.96%和6.97g/L,而对照的分别为38.56%和10.99g/L,蛋白质量促进率和生物量抑制率摇瓶批次培养时分别为28.2%和14.5%,摇瓶分批流加培养时分别达32.2%和36.6%。     

Hydrocarbon production from secondarily treated piggery wastewater by the green alga Botryococcus braunii

A laboratory study was conducted on the removal of nitrogen and phosphorus from piggery wastewater during growth of Botryococcus braunii UTEX 572, together with measurements of hydrocarbon formation by the alga. The influence was tested of the initial nitrogen and phosphorus concentration on the optimum concentration range for a culture in secondarily treated piggery wastewater. A high cell density (> 7 g L^–1 d. wt) was obtained with 510 mg L^–1 NO₃-N. Growth increased with nitrogen concentration at the basal phosphorus concentration (14 mg P L^–1). The growth rate was nearly independent ( = 0.027 0.030 h^–1) of the initial phosphate concentration, except under conditions of phosphate deficiency ( = 0.019 h^–1). B. braunii grew well in piggery wastewater pretreated by a membrane bioreactor (MBR) with acidogenic fermentation. A dry cell weight of 8.5 mgL^–1 and hydrocarbon level of 0.95 gL^–1 were obtained, and nitrate was removed at a rate of 620 mg NL^–1. These results indicate that pretreated piggery wastewater provides a good culture medium for the growth and hydrocarbon production by B. braunii.     

Copper tolerance in the green alga, Chlorella vulgaris

Abstract. The effect of sub-lethal concentrations of copper upon tolerant and non-tolerant strains of Chlorella vulgaris was investigated. Copper concentrations of 0.2 and 0.4 mg dm⁻³ increased the lag phase of both strains, the effect being greater in the non-tolerant strain. No difference was observed in the toxicity of copper to the photosynthetic rates of the isolated chloroplasts of either strain. However, significant differences were shown at the whole cell level.
Lower copper uptake was shown by the tolerant cells. In both strains initial uptake of copper was followed by a phase of desorption before cell division occurred. In cultures of both strains the concentration of ionic copper was decreased by complexation with extracellular organic material. Over a 14 day growth period more organic material was produced by the tolerant cells. The organic material produced by the tolerant cell formed organo-copper complexes which had a higher conditional stability constant.
It is proposed that the cell wall acts as a barrier to copper in the tolerant cells and prevents copper from affecting cell metabolism. Organo-copper complexation occurs at this barrier and this complex is then released into the medium.     

Studies on the regulation of assimilatory nitrate reductase in Ankistrodesmus braunii

In the green alga Ankistrodesmus braunii, all the activities associated with the nitrate reductase complex (i.e., NAD(P)H-nitrate reductase, NAD(P)H-cytochrome c reductase and FMNH₂-or MVH-nitrate reductase) are nutritionally repressed by ammonia or methylamine. Besides, ammonia or methylamine promote in vivo the reversible inactivation of nitrate reductase, but not of NAD(P)H-cytochrome c reductase. Subsequent removal of the inactivating agent from the medium causes reactivation of the inactive enzyme. Menadione has a striking stimulation on the in vivo reactivation of the inactive enzyme. The nitrate reductase activities, but not the diaphorase activity, can be inactivated in vitro by preincubating a partially purified enzyme preparation with NADH or NADPH. ADP, in the presence of Mg²⁺, presents a cooperative effect with NADH in the in vitro inactivation of nitrate reductase. This effect appears to be maximum at a concentration of ADP equimolecular with that of NADH.Abbreviations ADP Adenosine-5-diphosphate - AMP Adenosine-5-monophosphate - ATP Adenosine-5-triphosphate - FAD Flavin adenine dinucleotide - FMNH₂ Flavin adenine mononucleotide, reduced form - GDP Guanosine-5-diphosphate - MVH Methyl viologen, reduced form - NADH Nicotinamide adenine dinucleotide, reduced form - NADPH Nicotinamide adenine dinucleotide phosphate, reduced form     

Biomass and lipid enhancement in Ankistrodesmus sp. cultured with reused and minimal nutrients media

Microalgae are a promising feedstock for biofuel production. Lipid content in microalgae could be enhanced under nutrient depletion. This work investigated the effect of the nutrient on lipid accumulation in Ankistrodesmus sp. culture. Batch cultures were carried out using fresh BG11 medium, and after the harvest, the medium was reused for the next culture; this method was repeated two times. The maximum lipid productivity of 29.75 mg L^?1 day^?1 was obtained from the culture with the second reuse medium. In continuous cultures, Ankistrodesmus sp. was cultured in both fresh and modified BG11 mediums. The modified BG11 medium was adjusted to resemble the content of the first reuse medium. As a comparison between batch and continuous cultures, it was proven that the productivity in the continuous culture was better than in the batch, where the achievable maximum biomass and lipid were 188.30 and 38.32 mg L^?1 day^?1. The maximum lipid content of 34.22% was obtained from the continuous culture at a dilution rate of 0.08 day^?1, whereas the maximum saturated and unsaturated fatty acid productivities of 79.96 and 104.54 mg L^?1 day^?1 were obtained at a dilution rate of 0.16 day^?1.     

Application of unicellular algae Chlorella vulgaris for the mass-culture of marine rotifer Brachionus

Condensed suspension of Chlorellavulgaris was used for the food of the rotifer Brachionus plicatilis and B. rotundiformis inplace of Nannochloropsis oculata. Thisreport describes the characteristics of C. vulgaris as arotifer food in comparison with N. oculata and thepresent status of this field.The cell components of C. vulgarissuch as protein content, amino acids, minerals andvitamins are generally similar to those of N. oculata. However, the taxonomic status of thesealgal species are different. Based on thesimilarity of cell components, the dietary value ofC. vulgaris is equal in value to that of N. oculata for rotifer growth. Dietary value ofC. vulgaris can be improved by addition ofvitamin B₁₂. This improved C. vulgaris is currently widely used as an indispensable food organism for rotifer culture. Recent investigationshave shown that the use of the condensed suspensionof C. vulgaris makes it possible tosignificantly increase the rotifer density atharvest. Application of condensed C. vulgaris has made rotifer culture quite easy because theculture of N. oculata is no longer required,and intensive rotifer production in aquaculture cannow be realized.     

Hydrogen production by photosynthetic green algae

Oxygenic photosynthetic organisms such as cyanobacteria, green algae and diatoms are capable of absorbing light and storing up to 10-13% of its energy into the H-H bond of hydrogen gas. This process, which takes advantage of the photosynthetic apparatus of these organisms to convert sunlight into chemical energy, could conceivably be harnessed for production of significant amounts of energy from a renewable resource, water. The harnessed energy could then be coupled to a fuel cell for electricity generation and recycling of water molecules. In this review, current biochemical understanding of this reaction in green algae, and some of the major challenges facing the development of future commercial algal photobiological systems for H2 production have been discussed.     

Intracellular appearance of nitrite and nitrate in nitrogen-starved cells of Ankistrodesmus braunii

Summary The occurrence of heterotrophic nitrification in nitrogen-starved cells of Ankistrodesmus braunii was confirmed. The levels of nitrate and nitrite were measured over a period of four weeks. The validity of quantitative determinations in the presence of highly active nitrate and nitrite reductases is discussed. Whereas free hydroxylamine as an intermediate could not be detected, increased hydroxylamine oxidase activity was found in nitrogen-starved cultures. Nitrite reductase and hydroxylamine oxidase can be assigned to particles by sucrose density gradient centrifugation. The possible involvement of microbodies, which were found to be present in Ankistrodesmus, in metabolic processes during nitrogen starvation is discussed.Abbreviations NR nitrate reductase - NiR nitrite reductase - NNEDA N-(1-naphthyl)ethylenediaminedihydrochloride - DCPIP 2,6-dichlorophenolindophenol - EDTA ethylenediaminetetraacetic acid - TCA trichloroacetic acid - DAB 3,3-diaminobenzidine - AT 3-amino-1H-1,2,4-triazole - AMP 2-amino-2-methyl-1,3-propanediol     

Characterization of the Reversible Inactivation of Ankistrodesmus braunii Nitrate Reductase by Hydroxylamine

The photoreversible nature of the regulation of nitrate reductase is one of the most interesting features of this enzyme. As well as other chemicals, NH₂OH reversibly inactivates the reduced form of nitrate reductase from Ankistrodesmus braunii. From the partial activities of the enzyme, only terminal nitrate reductase is affected by NH₂OH. To demonstrate that the terminal activity was readily inactivted by NH₂OH, the necessary reductants of the terminal part of the enzyme had to be cleared of dithionite since this compound reacts chemically with NH₂OH. Photoreduced flavins and electrochemically reduced methyl viologen sustain very effective inactivation of terminal nitrate reductase activity, even if the enzyme was previously deprived of its NADH-dehydrogenase activity. The early inhibition of nitrate reductase by NH₂OH appears to be competitive versus NO₃⁻. Since NO₃⁻, as well as cyanate, carbamyl phosphate and azide (competitive inhibitors of nitrate reductase versus NO₃⁻), protect the enzyme from NH₂OH inactivation, it is suggested that NH₂OH binds to the nitrate active site. The NH₂OH-inactivated enzyme was photoreactivated in the presence of flavins, although slower than when the enzyme was previously inactivated with CN⁻. NH₂OH and NADH concentrations required for full inactivation of nitrate reductase appear to be low enough to potentially consider this inactivation process of physiological significance.     

Proliferation and differentiation of primary bovine myoblasts using Chlorella vulgaris extract for sustainable production of cultured meat

Recently, cultured meat obtained from livestock-derived cells is being considered as a sustainable food source that reduces the use of natural resources. This study aimed to show that nutrients extracted from Chlorella vulgaris were beneficial in the culture of primary bovine myoblasts (PBMs), a major cell source for cultured meat production. Nutrients (glucose, amino acids, and vitamins) present in the animal-cell culture media were effectively recovered from C. vulgaris using acid hydrolysis treatment. On culture in nutrient-free inorganic salt solution, cell death was induced in most PBMs after 6 days of cultivation. However, the addition of C. vulgaris extract (CVE) significantly improved PBM viability, which was comparable to the viability in conventional culture medium (Dulbecco's modified Eagle's medium). Furthermore, by adding horse serum to induce differentiation, the formation of myotubes was confirmed when CVE were used. Together, the results showed that CVE could be used as an alternative to the conventional culture medium for PBMs. These findings will not only lower the environmental risks associated with the establishment of this eco-friendly cell culture system, but also highlight microalgae as a potent nutrient source that can replace conventional grain-dependent nutrient sources.