Application Of Microalgae Research Articles

Analysis of functional relationships between the cell quantification variables in the microalgae Chlorella sorokiniana

The applications of microalgae are being increasingly explored, as they have a high rate of cell duplication and accumulation of lipids, ranging from 20-50% of their dry weight, reaching up to 80% under appropriate conditions. Their cultivation in artificial conditions has also increased, which has made it important to explore different microalga quantification methods and evaluate its growth kinetics. For algal quantification, it appears that both quantification methods by direct counting in a Neubauer chamber (density) and indirect counting methods such as reading in spectrophotometry (optical density) and dry weight (biomass), are important to validate the results quantification. The objective of this study was to verify the existence of a functional relationship between the variables used to quantify the microalgae Chlorella sorokiniana. For this purpose, linear regression analysis was applied to the variables of cell density, optical density, and dry biomass that were obtained by cultivating the microalgae at different concentrations. Using the equations generated from the regression analysis in Chlorella sorokiniana, it was possible to obtain ​​cell density values between 3 and 3.8 × 106 mL-1 and dry biomass values between 0.1 and 4.3 mg.mL-1 from the optical density values acquired using spectrophotometry with extreme precision, and this method was found to be highly feasible.

Analysis of autotrophic, mixotrophic and heterotrophic phenotypes in the microalgae Chlorella vulgaris using time-resolved proteomics and transcriptomics approaches

Some microalgae species including Chlorella vulgaris can, under light exposure, concurrently metabolize organic and inorganic carbon sources in a metabolic mode known as mixotrophy. In many cases the cells can generate high biomass yield under mixotrophy, which is highly desirable for future massive applications of microalgae biomass as industrial feedstock. However, there is no complete understanding of the molecular physiology of microalgae in mixotrophy. Therefore, we performed a time-series analysis of the proteome and transcriptome of Chlorella vulgaris during the transition from autotrophy to mixotrophy under continuous light, and then to heterotrophy in darkness in controlled bioreactor conditions.The results from biomass and cell growth characterization demonstrated that under mixotrophic growth the cells have enhanced growth rate, and transcriptomics data showed overexpressed genes related to chromosome organization, DNA-repair, and DNA replication. Moreover, our proteomics data revealed differentially expressed proteins and overrepresentation of proteins related to translation mechanism. The transcriptomics and proteomics analysis also indicated that the expression of genes of the glyoxylate cycle, oxylipin metabolism, myo-inositol synthesis pathway and a subset of thioredoxins were also modulated. Moreover, we performed the annotation of transcription factor and transcriptional regulator genes and the results revealed novel candidate regulator genes that were exclusively expressed during mixotrophic growth phase including members of MYB (V-myb avian myeloblastosis viral oncogene homolog) and bZIP (Basic Leucine Zipper) protein families. Thus, our findings indicated that the high specific growth rate observed in cells under mixotrophy is likely supported by the induction of abiotic stress tolerance mechanisms via inositol and its derivatives and increased resistance to oxidative stress through the modulation of the expression of thioredoxins.Therefore, the identification of novel candidate genes in mixotrophy may contribute to the development of microalgae strains with higher growth capacity and better performance for biomass production.

Microalgae based wastewater treatment for the removal of emerging contaminants: A review of challenges and opportunities

Emerging contaminants (ECs) are attracting considerable attention due to their potential risk to human health and ecosystem. The past decade has seen a renewed importance in microalgae for bioremediating ECs from wastewater. Several proof of concept studies have been published to rationalize the use of microalgae for bioremediating ECs at laboratory conditions. However, there has been little discussion on real world application of microalgae for bioremediation purposes. This review paper sheds new light on obstacles faced in commercial use of microalgae for bioremediating ECs. The presence of multiple ECs and their affinity for microalgae raise some concern about the validity of laboratory findings. Dynamic changes of environmental conditions and accidental contaminations can significantly influence rate of bioremediation in large scale system. Appropriate pilot scale studies may bridge the gap between the laboratory scale studies and commercial scale applications. Considering the fate of ECs in microalgal cell, more research is needed in the direction of biodegradation assisted bioremediation due to end use of algal biomass. In fact, a wide range of extremophile microalgae species can be screened for selective removal of ECs. In-depth investigations are needed to characterize the quality of wastewater effluent after the separation of microalgal biomass. Notably, life cycle analysis related studies are needed to look at the viability of microalgae assisted bioremediation of ECs.

Development of a species-specific transformation system using the novel endogenous promoter calreticulin from oleaginous microalgae Ettlia sp.

Microalgae not only serve as raw materials for biofuel but also have uses in the food, pharmaceutical, and cosmetic industries. However, regulated gene expression in microalgae has only been achieved in a few strains due to the lack of genome information and unstable transformation. This study developed a species-specific transformation system for an oleaginous microalga, Ettlia sp. YC001, using electroporation. The electroporation was optimized using three parameters (waveform, field strength, and number of pulses), and the final selection was a 5 kV cm−1 field strength using an exponential decay wave with one pulse. A new strong endogenous promoter CRT (Pcrt) was identified using transcriptome and quantitative PCR analysis of highly expressed genes during the late exponential growth phase. The activities of this promoter were characterized using a codon optimized cyan fluorescent protein (CFP) as a reporter. The expression of CFP was similar under Pcrt and under the constitutive promoter psaD (PpsaD). The developed transformation system using electroporation with the endogenous promoter is simple to prepare, is easy to operate with high repetition, and utilizes a species-specific vector for high expression. This system could be used not only in molecular studies on microalgae but also in various industrial applications of microalgae.

Iohexol removal and degradation-product formation via biodegradation by the microalga Chlorella vulgaris

Microalgae applications are becoming more and more diverse, from wastewater treatment to biofuel and plastics production. Another promising and sustainable application is the removal of organic compound from drinking water and wastewater sources. This study focused on the removal of the iodinated contrast media, iohexol by the microalga Chlorella vulgaris. C. vulgaris removed 40–50% of the iohexol from the medium in 27 days, 23–30% of which was biodegraded through two main pathways: oxidation and hydrolysis. Similar transformation pathways, producing the same degradation products, were observed for incubation with microalgae and for ozonation.

Microalgal biosorption of heavy metals: A comprehensive bibliometric review

Heavy metals in the effluents released from industrial establishments pose risks to the environment and society. Prevalent organisms such as microalgae in industrial wastes can thrive in this harmful environment. The connection of the metal-binding proteins of the microalgal cell wall to the metal ions of the heavy metals enables microalgae as an ideal medium for biosorption. The current literature lacks the review of various microalgae used as biosorption of heavy metals from industrial effluents. This work aims to comprehensively review the literature on the use of microalgae as a biosorption for heavy metals. The study summarizes the application of different microalgae for heavy metals removal by identifying the various factors affecting the biosorption performance. Approaches to quantifying the heavy metals concentration are outlined. The methods of microalgae to generate biocompounds to enable biosorption of heavy metals are itemized. The study also aims to identify the materials produced by microalgae to facilitate biosorption. The industrial sectors with the potential benefit from the adoption of microalgal biosorption of heavy metals are recognized. Moreover, the current challenges and future perspectives of microalgal biosorption are discussed.

Bioremediation of industrial effluents: How a biochar pretreatment may increase the microalgal growth in tannery wastewater

The application of microalgae in wastewater treatment is gaining increasing attention due to the possible environmental benefits of using photosynthetic organisms for bioremediation. Tannery wastewaters, however, may be inhibiting for microorganisms’ growth due to the presence of toxic compounds, especially chromium. In this work, we assessed the possibility of combining the application of biochar, as an adsorbent for metals including chromium, with microalgae cultivation for tannery wastewater treatment. Two different types of biochar (pinewood biochar, PB, and a commercial one, CB) were tested as a pretreatment step prior to cultivation of Chlorella protothecoides. The application of both types of biochar led to a significant increase in growth rates (61 % and 126 % for PB and CB, respectively) and nutrients removal compared to cultivation in raw wastewaters. Concerning the comparison between different biochars, it resulted that biochar production process and its physiochemical characteristics strongly affect Cr(III) adsorption performances, with CB removing 99.6 % from a synthetic medium in 5 min, compared to 83.4 % of PB in 3 h. Cr(III) adsorption on CB followed Freundlich isotherm model. The kinetics of adsorption was also addressed, and pseudo-second order kinetics was found to be the best fitted model for Cr(III) adsorption on CB. When applied to real tannery effluents, chromium adsorption performances were affected by the complexity of the medium

Application of microalgae cultivated on pine bark for the treatment of municipal wastewater in cylindrical photobioreactors

AbstractThe presented study concerns the efficiency of removing nutrients, organic compounds and metal cations from municipal sewage by a cylindrical photobioreactor (PBR) with the biomass of microalgae growing on pine bark. The study was conducted in two cylindrical PBRs fed with municipal wastewater for 42 days. PBRs were internally illuminated with red and blue light at night. The sewage was additionally enriched in CO2 and CaCO3. The concentration of NH4+, NO32−, PO43−, metal cations and organic carbon (TOC) was determined in the treated sewage. The results indicated that the development of algal‐bacterial biofilm contributed to the reduction of NH4+ (>99%), PO43− (96–99%) and TOC (71–77%) concentrations. Amongst the metal cations, the highest reduction of concentration was noted for Cu, K, Mn, Zn and Fe. Immobilisation of algae on pine bark is an effective method of wastewater treatment in PBR and supports the separation of proliferated biomass.

Microalgae: A Renewable Source for Wastewater Treatment and Feedstock Supply for Biofuel Generation

The search and exploitation of renewable clean energy sources have become crucial, because of the developing day by day interest for clean water and energy affected by the improvement of the economy, population, industrialization, urbanization, insufficient energy, climate abnormalities, and environmental pollution. The major cause of emissions of harmful gases into the environment is due to the high utilization of petroleum derivatives. In this way, it is paramount to explore environmentally sustainable energy sources for feasible advancement, to satisfy these expanding energy demands and to secure the environment. To mitigate these global problems, academic, industrial, and governmental sectors have engaged in a lot of brainstorming and research to surmount these difficulties, which have brought a steady flow of new information in the area of cultivation of microalgae in innovative technologies including photobioreactors and high rate algal ponds. In this respect, biomass generation from aquatic plants in enriched aquatic environments like wastewater has received considerable. Therefore, this review article provides comprehensive information on recent accounts on applications of microalgae in wastewater treatment using different technologies and their potentials in feedstock generation for biofuels applications. However, in the course of this study, high rate algal ponds (HRAP) and photobioreactors were found to be a reliable system for the cultivation of microalgae and wastewater treatment. Hence, the two-step method of dewatering methods is found to be the most effective approach for microalgae cultivation for wastewater treatment and generation of algal-based feedstock, taking into account high yield potentials and economic factors such as cost of operation and energy required for large scale algal biomass processing for biofuel generations.

Studia Doctorandorum Alumnae 2020

A kötet egyediségét az általánosságtól eltérő könyvformátum, az évente változó színű vászonkötés, valamint a borítón található arany nyomat adja. A borítón látható címermontázs különlegessége, hogy a Doktoranduszok Országos Szövetsége tudományos osztályait azonosító címerek egyes elemeinek a fehasználásával készült, amely Galambosi Barbara grafikusművész elgondolásai alapján alkotnak egységet az új grafikai elemben. Az I. kötetben három doktori disszertáció monografikus átdolgozása kapott helyet. Atanazovné Hartung Katalin A kék gazdaság fogalmának termeléselméleti megalapozása című doktori értekezésében elsőként definiálta a Kék Gazdaság koncepcióját a mainstream közgazdaságtan fogalmi keretei között, leszűkítve ezzel a vizsgálódás fókuszát a termeléselmélet területére. Grotte Judit Az internet használat a magyarországi szabadidős utazások megszervezése során című doktori disszertációja az I. kötet második részét képezi. A szerző doktori disszertációjában a turizmus és az internet kapcsolatát, pontosabban annak a hiányát vizsgálja. Horváth Orsolya az Azonosító és keresőkutyák kriminalisztikai alkalmazása című doktori munkájában szorosan a büntetőeljáráshoz kapcsolódó ismereteket kutat, amelyek elsődlegesen a bűnügyi szolgálati kutyák munkájához köthetők. Értekezésében a rendvédelmi szerveknél ehhez a szolgálati ághoz tartozó kutyák munkáját ismerteti, azonban eltekint a közrendvédelmi szolgálati ágnál alkalmazott őr és járőrkutyák részletes bemutatásától. A II. kötetben elsőként Poreisz Veronika A területi és a vállalati versenyképesség összefüggései a magyar nagyvárosok példáján című doktori értekezése kapott helyet. A disszertáció egy multidiszciplináris dolgozat, hiszen a regionális gazdaságtan, a menedzsment és a vállalati pénzügy területeit kapcsolja össze. Szabó Piroska az Anaerob fermentációs folyamatok optimálása a mikroalga alkalmazhatóság továbbá a mikroelem adagolás tekintetében című doktori munkájában a világ fokozódó energiaigényéről, a fosszilis energiatartalékok kimerülésének veszélyéről, valamint használatuk környezetkárosító hatása révén kialakult szénalapú társadalmaink által kezelt megújuló energiaforrásokban rejlő lehetőségekről ír kutatásában. Ürmösné Simon Gabriella az Egynyelvűek és görög–magyar kétnyelvűek kommunikációjának összehasonlító elemzése a nemek tükrében című doktori értekezése zárja a II. kötetet. A szerző kutatásának tárgya az egynyelvűek és a görög–magyar kétnyelvűek kommunikációjának összehasonlítása, nemek szerinti aspektusból.

Application of Microalgae and Agrobost Symbiotic Mutualism Technology in Palm Oil Mill Effluent (POME) Processing

The purpose of this study was to get the selected treatment mutualism symbiosis between microalgae (Chlorella sp.) and agrobost, thus can decrease of pollution level of Palm Oil Mill Effluent (POME) according to standard quality. This research used a completely randomized design (CRD) with 5 treatments and 3 replications. The treatments in this addition was microalgae Chlorella sp. as much 800 ml/L (Abundance of cells 6.3 x 106 cell/ml) of POME with some variations concentrations of Agrobost (0%, 1%, 2%, 3%, and 4%). The data obtained were analyzed statistically using ANOVA and DNMRT at 5% level. The result showed that the addition of Agrobost had significant affect for COD, BOD, oil, pH and TSS. The treatment chosen from the result of this research was the P4 treatment showed the highest level of reduction which had COD 91.67%, BOD 95.93%, Oil 80.18%, TSS 71.69% and pH 12.08%.

Pre-concentration of microalga Euglena gracilis by alkalescent pH treatment and flocculation mechanism of Ca3(PO4)2, Mg3(PO4)2, and derivatives

BackgroundMicroalgae are widely be used in carbon sequestration, food supplements, natural pigments, polyunsaturated fatty acids, biofuel applications, and wastewater treatment. However, the difficulties incurred in algae cell separation and harvesting, and the exorbitant cost required to overcome these challenges, are the primary limitations to large-scale industrial application of microalgae technology.ResultsHerein, we explore the potential of inducing flocculation by adjusting the pH for pre-concentrating Euglena gracilis. Our results demonstrate that flocculation can be induced by increasing the medium pH to 8.5; however, most of the algae cells were broken by increasing the pH > 10. Magnesium phosphate, calcium phosphate, and their derivatives precipitation jointly led to flocculation, although calcium phosphate and its derivatives precipitation had a greater effect.ConclusionsThis study demonstrates that pH treatment-induced flocculation is efficient and feasible for the pre-concentration of E. gracilis under a pilot-scale culture system. Moreover, it also maintained the microalgae cells’ integrity, chlorophyll production, and increased paramylon production. These findings provide a theoretical basis for reducing the cost of large-scale E. gracilis harvesting; as well as provide a reference for harvesting other microalgae.

Effect of Chlorella vulgaris on Growth and Photosynthetic Pigment Content in Swiss Chard (Beta vulgaris L. subsp. cicla).

Microalgae application in agriculture is an alternative measure that could be highly beneficial to plants. The application of microalgae Chlorella vulgaris S45 and its effect on plant growth and pigment content in Swiss chard were investigated. In the treatments, 5% and 10% algal suspensions were applied by spraying on plants and in soil, respectively. C. vulgaris S45 affected the initial growth of Swiss chard and the content of photosynthetic pigments positively. The correlation analysis proved the existence of statistically significant interdependency between chlorophyll a (Chl a) content and leaf number (r = 0.876 at p < 0.05), and chlorophyll b (Chl b) content and fresh leaf weight (r = 0.783 at p < 0.05).

The application of microalgae in removing organic micropollutants in wastewater

Micropollutants have become a serious environmental problem with several negative outcomes for human health and ecosystems. Many efforts have been made to remove micropollutants using a variety of physical, chemical and biological methods. By far, the most attention has been paid to microalgae-based technologies for wastewater treatment in order to obtain high-quality effluents, recover algal biomass for fertilizers, protein-rich feed, biofuel, and put them to other practical use. This paper reviews the potential of microalgae-based systems for the removal of organic micropollutants from open ponds to closed photobioreactors coupled by suspended microalgal cells, immobilized cells, or microalgae-microbial consortia. The inhibition of micropollutants on microalgae growth as well as micropollutant removal mechanisms performed by microalgae-based systems are also discussed. Other treatment methods for the removal of micropollutants are analyzed to show the advantages and limitations of microalgae-based treatment strategies, from which some possible combined systems can be suggested. Finally, some recommendations for future studies on this topic are proposed.

Production of extracellular polysaccharides and phycobiliproteins from Tolypothrix sp. PCC7601 using mechanical milking systems

The bio-industrial application of microalgae has gained much attention in recent years. One of the challenges in this field is to lower the cultivation and harvest costs and to achieve the steady productivity. To address this, new systems have been proposed, in which the products are extracted without killing the algal cells. These non-destructive extraction systems are called “milking.” Some of the milking systems reported so far are continuous processes where culturing and milking occur simultaneously, and the others are a periodic process where cells are cyclically cultured and milked. These systems are based on the organic solvent extraction of non-polar products, such as lipids, terpenes, and carotenoids. However, a special facility required for handling organic solvents increases the costs and solvents lost during milking need to be recouped. In this study, we examined a solvent-free method, based on mechanical milking using a shearing disperser (glass homogenizer). We cultured the N2-fixing filamentous cyanobacteria, Tolypothrix sp. PCC7601 in non-sterile agricultural water and performed long-term (87 days) milking cycles to harvest the extracellular carbohydrates and phycobiliproteins. As a result, the productivity of extracellular carbohydrates and the cell densities remained constant throughout the milking cycle, yielding 90–140 mg/L of extracellular carbohydrates every 3 weeks. Our results demonstrated that mechanical milking is a practical and effective method that can be used to harvest products from algae steadily.

Optimal control of microalgae growth using linear quadratic regulator method with firefly algorithm optimization

Microalgae is an important potential resource for various industrial applications. In the industry, there are a variety of processed products from algae biomass. Lipids from microalgae used for biofuell, humans and animals in food supplements while in the pharmaceutical, lipids used as a vitamin or protein. The other application of microalgae captures CO 2 and wastewater treatment. This research discusses the optimal control of microalgae growth with variable control are carbon dioxide and nutrients. In this case, the methodology is the Linear Quadratic Regulator method. In the Linear Quadratic Regulator method, there are weights in which the value is determined by trial and error in the matrices Q and R. The method of optimizing the weight value is required to optimize the weight. In this paper, the firefly algorithm is used to optimize the matrix values for Q and R. Application of firefly algorithm is able to optimally increase microalgae growth, so that the biomass produced is also abundant. The using of Firefly Algorithms optimization in the LQR method can increase algal concentration by 63.3% of the initial concentration.

Chlorella vulgaris on the cathode promoted the performance of sediment microbial fuel cells for electrogenesis and pollutant removal

The lack of electron acceptors in cathode has limited the widespread application of sediment microbial fuel cells (SMFCs). In this study, Chlorella vulgaris (C. vulgaris) was added to the cathode to produce oxygen as an electron acceptor. The synergistic effects between C. vulgaris and electrogenic microorganisms in SMFCs were investigated, and were shown to enhance biodegradation of organic matter in sediments and convert chemical energy into electrical energy. Results showed that the addition of C. vulgaris on the cathode of SMFCs significantly reduced their internal resistance. The low algae concentration SMFC group reduced the initial internal resistance by 67.4% under illumination and produced a maximum power density of 5.17 W/m3, which was 6 times higher than that of SMFCs without addition of C. vulgaris. We also obtained organic matter removal efficiencies 37.2% higher after 16 days, which accelerated the startup time for three times. It was demonstrated that IEF-N and OP, respectively, were forms of nitrogen and phosphorus removed by SMFCs. Additionally, high-throughput sequencing of microbial communities indicated that C. vulgaris increased the abundance of electrogenic bacteria (Geobacter and Desulfobulbaceae) in the anode and types of photosynthetic bacteria that support oxygen production in the cathode. The combined application of microalgae- and SMFC-based technologies offer a promising remediation approach for organically-contaminated sediments.

Enrichment of f/2 medium hyperaccumulates biomass and bioactive compounds in the diatom Phaeodactylum tricornutum

Photosynthetic microalgae have garnered research attention due to their inherent advantageous characteristics, however, commercial exploitation of algae is still hampered by their relatively compromised overall productivity. Thus, it is of paramount significance to design a strategy to concurrently enhance the growth rate and compounds production. In this study, we interrogated the impact of fortifying bacterial growth medium components in the conventional f/2-medium for microalgae. Our results showed that supplement of yeast extract and tryptone significantly increased cell growth of the model diatom Phaeodactylum tricornutum. Particularly, cell biomass and triacylglyceride content increased up to 3.48-fold and 2.13-fold in the stationary phase, respectively. Besides, fucoxanthin content increased by 1.7-fold. Transcript abundance of key genes involved in carotenoid synthesis also increased significantly. Overall, the results exemplified a feasible and promising strategy to simultaneously enhance the biomass and accumulation of triacylglyceride and fucoxanthin for industrial applications of microalgae.

Microalgae Water Bioremediation: Trends and Hot Topics

The need to reduce costs associated with the production of microalgae biomass has encouraged the coupling of process with wastewater treatment. Emerging pollutants in municipal, industrial, and agricultural wastewaters, ranging from pharmaceuticals to metals, endanger public health and natural resources. The use of microalgae has, in fact, been shown to be an efficient method in water-treatment processes and presents several advantages, such as carbon sequestration, and an opportunity to develop innovative bioproducts with applications to several industries. Using a bibliometric analysis software, SciMAT, a mapping of the research field was performed, analyzing the articles produced between 1981 and 2018, aiming to identifying the hot topics and trends studied until now. The application of microalgae on water bioremediation is an evolving research field that currently focuses on developing efficient and cost-effective treatments methods that also enable the production of add-value products, leading to a blue and circular economy.

Outdoor Large-Scale Cultivation of the Acidophilic Microalga Coccomyxa onubensis in a Vertical Close Photobioreactor for Lutein Production

The large-scale biomass production is an essential step in the biotechnological applications of microalgae. Coccomyxa onubensis is an acidophilic microalga isolated from the highly acidic waters of Río Tinto (province of Huelva, Spain) and has been shown to accumulate a high concentration of lutein (9.7 mg g−1dw), a valuable antioxidant, when grown at laboratory-scale. A productivity of 0.14 g L−1 d−1 was obtained by growing the microalga under outdoor conditions in an 800 L tubular photobioreactor. The results show a stable biomass production for at least one month and with a lutein content of 10 mg g−1dw, at pH values in the range 2.5–3.0 and temperature in the range 10–25 °C. Culture density, temperature, and CO2 availability in highly acidic medium are rate-limiting conditions for the microalgal growth. These aspects are discussed in this paper in order to improve the outdoor culture conditions for competitive applications of C. onubensis.