Microalgal Extracts Research Articles

Improvement of the Oxidative Stability of Sesame Oil Using Spirulina as a Natural Antioxidant

Background: Nowadays, natural antioxidants are used to replace synthetic antioxidants for delaying or preventing the oxidation of edible oils. In this study, phenolic compounds and antioxidant properties of methanol extracts of Spirulina microalgae (Arthrospira platensis) were measured. Methods: Phenolic content was measured by Folin–Ciocalteau method and antioxidant activity was measured by the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) method. Also, spirulina microalgae as natural antioxidant, was added to sesame oil for improving its oxidative stability. The effects of methanol extract of these microalgae in four concentrations (0, 500, 1000 and 2000 ppm) and synthetic antioxidants of butylated hydroxyl anyzole (BHA) and butylated hydroxytoluene (BHT) in two levels (100 and 200 ppm) in retarding the sesame oil oxidation were examined. Results: The results showed that spirulina extract had 50.54 mg gallic acid/g samples total phenols and antiradical activity (84.38%). By increasing the concentration of the extracts, the oxidation process decreased. Methanol extract at 1000 ppm concentration had the highest antiradical activity than other concentrations and its antiradical activity was alike the synthesis antioxidant of BHA. By Increasing of storage period, peroxide values in 500 and 1000 ppm of spirulina extracts first increased then decreased and in other treatment increased. During storage time thiobarbituric acid index increased. However, this increase was higher in control treatment than others. Conclusion: According to the stated content, it can be said that methanol extracts of spirulina have appropriate antioxidant properties and spirulina can be used as a natural antioxidant to improve the oxidative stability of sesame oil.

Biphasic short time heat degradation of the blue microalgae protein phycocyanin from Arthrospira platensis

Abstract Stability of colorants is concerning for food coloring matrices, particularly for the only natural blue food coloring, phycocyanin. The Spirulina-based microalgal extract is mainly comprised of heat sensitive protein-chromophore complexes, C-phycocyanin and allophycocyanin. Although frequently encountered in food processing, the impact of short time heat treatments has not been studied systematically. Here, phosphate buffered phycocyanin solution was heated in batch and emerging continuous processing systems, both characterized with high surface-to-volume ratios allowing isothermal conditions with residence times down to 5 s. Absorption scans revealed biphasic degradation of phycocyanin color activity to about 30% within 30 s at T ≥ 70 °C. Kinetic modelling of the color decay via an nth order approach contradicts previously assumed linear first order kinetics with a best fitting empirical reaction order of n = 6. It shows that decay in phycocyanin color activity is not a single process but encompasses C-phycocyanin and allophycocyanin aggregate disintegration and denaturation. Industrial relevance Central to this study is the color stability of phycocyanin, which is a high value component, derived from the emerging food source microalgae. It is also the only naturally obtained blue food coloring available to the food industry. Insights could be gained on the color degradation kinetics by treating an industry relevant formulation in batch and emerging scalable continuous systems via micro process engineering. This data will directly support food research and development activities to optimize and minimize blue color losses within multiple product categories.

Inhibitory effect of microalgae and cyanobacteria extracts on influenza virus replication and neuraminidase activity.

BackgroundThe influenza virus can cause seasonal infections with mild to severe symptoms, circulating worldwide, and it can affect people in any age group. Therefore, this infection is a serious public health problem that causes severe illness and death in high-risk populations. Every year, 0.5% of the world’s population is infected by this pathogen. This percentage can increase up to ten times during pandemics. Influenza vaccination is the most effective way to prevent disease. In addition, anti-influenza drugs are essential for prophylactic and therapeutic interventions. The oseltamivir (OST, a neuraminidase inhibitor) is the primary antiviral used in clinics during outbreaks. However, OST resistant viruses may emerge naturally or due to antiviral pressure, with a prevalence of 1–2% worldwide. Thus, the search for new anti-influenza drugs is extremely important. Currently, several groups have been developing studies describing the biotechnological potential of microalgae and cyanobacteria, including antiviral activity of their extracts. In Brazil, this potential is poorly known and explored.MethodsWith the aim of increasing the knowledge on this topic, 38 extracts from microalgae and cyanobacteria isolated from marine and freshwater biomes in Brazil were tested against: cellular toxicity; OST-sensitive and resistant influenza replications; and neuraminidase activity.ResultsFor this purpose, Madin-Darby Canine Kidney (MDCK)-infected cells were treated with 200 μg/mL of each extract. A total of 17 extracts (45%) inhibited influenza A replication, with seven of them resulting in more than 80% inhibition. Moreover, functional assays performed with viral neuraminidase revealed two extracts (from Leptolyngbya sp. and Chlorellaceae) with IC50 mean < 210 μg/mL for influenza A and B, and also OST-sensitive and resistant strains. Furthermore, MDCK cells exposed to 1 mg/mL of all the extracts showed viability higher than 80%.DiscussionOur results suggest that extracts of microalgae and cyanobacteria have promising anti-influenza properties. Further chemical investigation should be conducted to isolate the active compounds for the development of new anti-influenza drugs. The data generated contribute to the knowledge of the biotechnological potential of Brazilian biomes that are still little explored for this purpose.

Study on the migration characteristics of nitrogen and sulfur during co-combustion of oil sludge char and microalgae residue

Integrated thermal treatment (coupled pyrolysis and combustion) has great potential to be a clean and effective method for massive oil sludge (OS) utilization. Produced OS pyrolysis char (OS char) can be effectively utilized through fluidized bed incinerator with auxiliary fuels. A study on co-combustion of OS char and microalgae extraction residue (MR) were conducted with a coupled thermogravimetric-mass spectroscopy system (TG-MS), and a fluidized bed reactor system. Co-combustion process of OS char and MR could be divided into three stages, including water evaporation, volatiles release and combustion, fixed carbon combustion and minerals decomposition. SO2 emissions decreased with the increase of MR ratio and NOx emissions initially decreased followed by an increase until the MR ratio exceeded 50%. Both NOx and SO2 emissions initially increased before a decrease with combustion temperature raised. Higher excessive air ratio (α) promoted the pollutants emission. Pyrrole (N-5) content increased with the increase of MR ratio and more N-5 and pyridine (N-6) could be converted to oxidized nitrogen (N-X) in the bottom ash under a higher temperature during OS combustion. Besides, the temperature range (900–1000 °C) was conductive to SO2 release, and S4+ formation.

Delving into the Polar Lipidome by Optimized Chromatographic Separation, High-Resolution Mass Spectrometry, and Comprehensive Identification with Lipostar: Microalgae as Case Study.

The work describes the chromatographic separation optimization of polar lipids on Kinetex-EVO, particularly focusing on sulfolipids in spirulina microalgae ( Arthrospira platensis). Gradient shape and mobile-phase modifiers (pH and buffer) were tested on lipid standards. Different conditions were evaluated, and resolution, peak capacity, and peak shape were calculated both in negative mode, for sulfolipids and phospholipids, and in positive mode, for glycolipids. A high-confidence lipid identification strategy was also applied. In collaboration with software creators and developers, Lipostar was implemented to improve the identification of phosphoglycerolipids and to allow the identification of glycosylmonoradyl- and glycosyldiradyl-glycerols classes, the last being the main focus of this work. By this approach, an untargeted screening also for searching lipids not yet reported in the literature could be accomplished. The optimized chromatographic conditions and database search were tested for lipid identification first on the standard mixture, then on the polar lipid extract of spirulina microalgae, for which 205 lipids were identified.

Anti-Bacterial Adhesion Activity of Tropical Microalgae Extracts.

The evolution of regulations concerning biocidal products aimed towards an increased protection of the environment (e.g., EU Regulation No 528/2012) requires the development of new non-toxic anti-fouling (AF) systems. As the marine environment is an important source of inspiration, such AF systems inhibiting the adhesion of organisms without any toxicity could be based on molecules of natural origin. In this context, the antibiofilm potential of tropical microalgal extracts was investigated. The tropics are particularly interesting in terms of solar energy and temperatures which provide a wide marine diversity and a high production of microalgae. Twenty microalgal strains isolated from the Indian Ocean were studied. Their extracts were characterized in terms of global chemical composition by high resolution magic angle spinning (HR-MAS) and nuclear magnetic resonance (NMR) spectroscopy, toxicity against marine bacteria (viability and growth) and anti-adhesion effect. The different observations made by confocal laser scanning microscopy (CLSM) showed a significant activity of three extracts from Dinoflagellate strains against the settlement of selected marine bacteria without any toxicity at a concentration of 50 μg/mL. The Symbiodinium sp. (P-78) extract inhibited the adhesion of Bacillus sp. 4J6 (Atlantic Ocean), Shewanella sp. MVV1 (Indian Ocean) and Pseudoalteromonas lipolytica TC8 (Mediterranean Ocean) at 60, 76 and 52%, respectively. These results underlined the potential of using microalgal extracts to repel fouling organisms.

Enhancement of the energy yield from microalgae via enzymatic pretreatment and anaerobic co-digestion

Microalgae have been considered as one of the most promising biomass resources for the generation of biodiesel, whereas algal residues (AR) after lipid extraction need to be utilized to enhance its economy and sustainability. This study proposed an integrated biochemical method for microalgae Chlorella sp. processing to achieve a high energy yield (12.33 KJ g−1VS). The microalgae were first pretreated with mixed enzymes for lipid extraction. After that, the AR obtained from the lipid extraction of microalgae was co-digested with energy grass (GR) Pennisetum hybrid for methane production. Results indicated that the lipid yield from microalgae was enhanced by 54.45% with mixed enzymes pretreatment of cellulase, xynalase and pectinase compared to that without enzymatic pretreatment. The maximal methane yield (207.35 ± 15.66 mLCH4 g−1VS) of AR and GR co-digestion was obtained with the AR and GR VS ratio at 1:3. Energy yields evaluation based on the biodiesel and methane yields indicated that the energy yield for this two-step combined method was 169% higher than that for biodiesel alone. Thus, the proposed integrated approach was verified to be applicable for microalgae processing for energy production.

Bioprospecting freshwater microalgae for antibacterial activity from water bodies associated with abandoned mine sites

:Bacterial resistance to antibiotics necessitates the search for new sources of microorganisms able to produce these needed molecules, which are typically secondary metabolites produced as a protective mechanism. Microalgae can produce a wide range of secondary metabolites as a response to environmental stress but have been the subject of little research as potential sources of antibiotics. As a step towards assessing their potential, we isolated 40 freshwater green microalgae from water bodies with a wide range of metal concentrations and pH values that were near abandoned mine sites in northern Canada. Microalgae from this region and these types of water bodies had not been previously investigated for antibacterial properties. Forty methanolic microalgal extracts were obtained, analysed and tested against Gram-positive and Gram-negative bacteria, and 37.5% inhibited the human pathogen Staphylococcus aureus (Bacilli). This is a higher ‘hit-rate’ than in previously published results, and furthermore, the minimum inhibitory concentrations against S. aureus were notably much lower than any other reported work. This is the first time such environments have been assessed, and whilst no clear association was observed between the metals and pH analysed and antibacterial activity, the findings indicate that microalgae from anthropogenically stressed environments are a potential source of antibacterial compounds. That is, sites that are typically regarded as having no value and often very negatively perceived are potential sources of valuable bioactive compounds. Therefore, future studies are necessary to determine what environmental thresholds are associated with the antibacterial activity of the freshwater green microalgae thriving in these environments.

Techniques for harvesting, cell disruption and lipid extraction of microalgae for biofuel production

ABSTRACTMicroalgal biofuels are one of the best alternatives to replace the nonrenewable fossil fuels. Microalgae offer various advantages, the most beneficial being their high growth rate and ability to grow on waste waters. Many microalgal species have been assessed and studied for biofuel production, and have shown varying amounts of lipid contents. Harvesting the microalgae and extracting the stored lipids is a major hurdle for biofuel production technology, due to their tough cell walls. This review focuses on techniques for harvesting, cell disruption and lipid extraction of microalgae used for biofuel production.

Maximizing the efficacy of Trichoderma to control Cephalosporium maydis, causing maize late wilt disease, using freshwater microalgae extracts

The main goal of this study was enhancing the biocontrol activity of Trichoderma spp. (T. harzianum, T. koningii, T. viride, and T. virens) against Cephalosporium maydis, the cause of late wilt disease in maize. Five isolates of C. maydis were isolated from diseased maize plants, showing late wilt symptoms, and were collected from infected maize fields in Gharbia Governorate, Egypt. Pathogenicity test revealed that all C. maydis isolates were able to attack maize plants (cv. Baladi), which cause late wilt disease. Isolate 3 (Cm3) was the most virulent of them. In in vitro experiments, vegetative growth of the mycelium of C. maydis was highly inhibited after opposite sides’ treatment by Trichoderma species on Potato Dextrose Agar plates amended with Chlorella vulgaris extracts (cool and hot extracts) than unamended one. Formulation of C. vulgaris extracts and Trichoderma spp. were prepared. The formulations maintained the capacity of Trichoderma spp. to inhibit growth of the pathogen for up to 1 year when stored at both room temperature or at 7 °C. These formulations (3-day-old) were examined for biological control activities against late wilt disease of maize. Under greenhouse and field conditions, all treatments reduced late wilt incidence compared to the untreated control. Treatments involved Trichoderma spp., and C. vulgaris extracts were more effective than that used individually. Both of the C. vulgaris extracts, with each of T. virens and T. koningii, were the most effective treatments in this respect. Under greenhouse conditions, formulation treatments (C. vulgaris extracts and Trichoderma spp.) significantly increase the plant growth of maize plants, i.e., plant height and plant dry weight as compared to the non-treated control either in infested or in un-infested soil with C. maydis. Under field conditions, these formulations increased the grain yield as well as ear parameters as compared with either C. vulgaris extracts or Trichoderma spp. alone as well as non-treated control. This study suggests that the efficacy of Trichoderma spp. was enhanced with C. vulgaris extracts and these formulations can be developed as bio-fungicides for minimizing the late wilt disease caused by C. maydis in maize.

Technical feasibility of residual biomass of microalgae Desmodesmus sp. after supercritical extraction: evaluation of chemical composition

Supercritical extraction process has been used to obtain bioactive compounds from microalgae biomass that differs in composition because it has protein, esters, carotenoids, chlorophyll, enzymes, antibiotics, vitamins, and hydrocarbons. Due to this, the study of the technical feasibility of supercritical extraction of microalgae and the evaluation of the chemical composition from residual biomass of microalgae Desmodesmus sp. is the goal of this work looking for its reutilization in cosmetic, food and pharmaceutical applications. The experimental unit used is formed, basically, of a 42 mL extractor, a high pressure pump, and a micro-metering valve used for sampling. The study showed that it was obtained a higher mass yield at 90 °C and 440 bar of pressure. The residual biomass still contained a high percentage of proteins and carbohydrates, indicating that it could be used in nutraceuticals applications, and as biofertilizers.

Antibacterial Potential of Chlorella vulgaris and Dunaliella salina Extracts Against Streptococcus mutans

Background and Objectives: Chlorella vulgaris and Dunaliella salina has been utilized as a part of nourishment and medicine to enhance the human way of life. This work was directed to assess the impacts of chloroform, methanol, and acetone (in ratio of 2/1/1 respectively) extract from C. vulgaris and D. salina on in-vitro biofilms formed by Streptococcus mutans along with their antibacterial activity. Methods: The standardized combinatorial extract was primarily examined for their antimicrobial properties using disc diffusion, well diffusion, minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) methods. The crystal violet assay was used for assessing anti-biofilm activity of S. mutans. Moreover, toxicity properties of these extracts were evaluated on Brine shrimp Artemia urmiana. Results: The best observed clear zones were 13.5 ± 0.92 mm for C. vulgaris and 18.5 ± 0.97 for D. salina in disc diffusion assay as well as 19 ± 0.87 mm for C. vulgaris and 25.4 ± 0.97 mm for D. salina in well diffusion assay. In addition, significant antibiofilm activity was recorded in the concentration of 4 mg/ml for C. vulgaris and 2 mg/ml for D. salina. Findings indicated appropriate antimicrobial activity for D. salina and C. vulgaris extract. Conclusions: In addition, the biofilms of S. mutans were more effectively prohibited by D. salina extract than C. vulgaris extract. Moreover, D. salina extract showed less mortality in comparison with C. vulgaris extract in brine shrimp mortality test. The anti-adherent and antibacterial potential of both microalgae on in vitro biofilms formed by S. mutans were verified, which provides the importance of studies regarding these microalgae extracts for controlling dental plaque formation and consequent dental cavities formation.

Application of Fungicides and Microalgal Phenolic Extracts for the Direct Control of Fumonisin Contamination in Maize.

Fungicides and, for the first time, microalgal phenolic extracts (MPE) from Spirulina sp. and Nannochloropsis sp. were applied on maize culture media under field conditions to evaluate their ability to minimize Fusarium species development and fumonisin production. An in vitro assay against F. verticillioides was carried out using maize grains as the culture medium. An open-field experiment was carried out in Northwest Italy under natural infection conditions. The compared treatments were factorial combinations of two insecticide treatments (an untreated control and pyrethroid, used against European Corn Borer), four antifungal treatments (an untreated control, MPE from Spirulina sp., MPE from Nannochloropsis sp., and a synthetic fungicide), and two timings of the application of the antifungal compounds (at maize flowering and at the milk stage). The MPE compounds were capable of inhibiting fumonisin production in vitro more efficiently than tebuconazole. Insecticide application reduced the infection by Fusarium species and subsequent fumonisin contamination. However, fumonisins in maize fields were not significantly controlled by either fungicide or MPE application.

Fractionation of proteins and carbohydrates from crude microalgae extracts using an ionic liquid based-aqueous two phase system

Abstract Mild, simple and efficient recovery methods are required to obtain high-value microalgae proteins. As a promising extraction method, an Aqueous two phase system (ATPS) was used to partition proteins from crude microalgae extracts obtained from two green microalgae of industrial interest: Neochloris oleoabundans and Tetraselmis suecica . Furthermore, the Non-Random Two Liquids model (NRTL) was applied to describe both the phase diagram and the partition coefficient of total protein. It was observed that total protein preferentially concentrates in the top phase. Additionally, no significant effect on partition or extraction efficiency was noted at different tie lines. Experimental data indicate that proteins and sugars are selectively fractionated in top and bottom phases respectively. The model provided a good representation of the experimental data for the liquid-liquid equilibrium. Moreover, the model also led to a good representation of the partitioning data for two reference proteins, Rubisco and Bovine Serum Albumin (BSA), as well as for total protein from crude microalgae extracts.

Evaluation of a partially de-oiled microalgae product in nursery pig diets.

Although microalgae can be used as a source of energy and macronutrients in pig diets, there is limited information on the use of partially de-oiled microalgae coproducts in swine feeding programs. The objectives of this study were to evaluate the effects of a partially de-oiled microalgae extract (MAE) in nursery pig diets on growth performance and health status. A total of 300 pigs (initial BW = 6.3 ± 2.1 kg) were used in a 42-d experiment. Treatments included a standard corn-soybean meal control diet, and diets containing 1, 5, 10, or 20% MAE replacing primarily corn. The ME content of MAE was calculated from the chemical composition, and diets were formulated to meet or exceed nutrient requirements for nursery pigs. Pigs were stratified by weaning BW into 12 blocks in a randomized complete block design, with sex distributed evenly among blocks. Pens of pigs (5 pigs/pen) were assigned randomly within block to one of five dietary treatments. Pig BW and feed disappearance were recorded weekly. On day 42, 30 pigs were harvested and sections of the jejunum and ileum were collected for gut morphology analysis, and a liver sample was collected for metabolomic analysis using liquid chromatography-mass spectroscopy. Data were analyzed by ANOVA with diet as treatment effect, and contrasts were used to test linear or quadratic effects of dietary MAE inclusion level. Overall, pigs fed 1% and 5% MAE had the greatest (quadratic P < 0.05) ADG, resulting from greater (quadratic P < 0.05) ADFI. There was a tendency for a greater number of pigs requiring injectable treatments (P = 0.16) and a greater mortality (P = 0.14) in pigs fed the control diet than pigs in any of the diets with the MAE. Final BW increased (P < 0.05) for pigs fed 1% and 5% MAE diets. The improvements in ADG were not explained by differences in mucosa height or goblet cell count among dietary treatments. Pigs fed diets containing 1% or 5% MAE had relatively less concentration (P < 0.05) of ammonia in the liver and had changes in metabolites associated with the urea cycle. In conclusion, feeding MAE resulted in increased growth responses and may have beneficial health effects when fed to nursery pigs.

Antioxidant Potential of Extracts Obtained from Macro- (Ascophyllum nodosum, Fucus vesiculosus and Bifurcaria bifurcata) and Micro-Algae (Chlorella vulgaris and Spirulina platensis) Assisted by Ultrasound

Background: Natural antioxidants, which can replace synthetic ones due to their potential implications for health problems in children, have gained significant popularity. Therefore, the antioxidant potential of extracts obtained from three brown macroalgae (Ascophyllum nodosum, Fucus vesiculosus and Bifurcaria bifurcata) and two microalgae (Chlorella vulgaris and Spirulina platensis) using ultrasound-extraction as an innovative and green approach was evaluated. Methods: Algal extracts were obtained by ultrasound-assisted extraction using water/ethanol (50:50, v:v) as the extraction solvent. The different extracts were compared based on their antioxidant potential, measuring the extraction yield, the total phenolic content (TPC) and the antioxidant activity. Results: Extracts from Ascophyllum nodosum (AN) and Bifurcaria bifurcata (BB) showed the highest antioxidant potential compared to the rest of the samples. In particular, BB extract presented the highest extraction (35.85 g extract/100 g dry weight (DW)) and total phenolic compounds (TPC) (5.74 g phloroglucinol equivalents (PGE)/100 g DW) yields. Regarding the antioxidant activity, macroalgae showed again higher values than microalgae. BB extract had the highest antioxidant activity in the ORAC, DPPH and FRAP assays, with 556.20, 144.65 and 66.50 µmol Trolox equivalents (TE)/g DW, respectively. In addition, a correlation among the antioxidant activity and the TPC was noted. Conclusions: Within the obtained extracts, macroalgae, and in particular BB, are more suitable to be used as sources of phenolic antioxidants to be included in products for human consumption. The relatively low antioxidant potential, in terms of polyphenols, of the microalgae extracts studied in the present work makes them useless for possible industrial applications compared to macroalgae, although further in vivo studies evaluating the real impact of antioxidants from both macro- and micro-algae at the cellular level should be conducted.

Effect of microalgae addition on active biodegradable starch film

Despite its great importance, the traditional packaging is produced from non-renewable and non-biodegradable sources, causing several environmental problems. Therefore, biodegradable packaging has been attracting attention and interest from researchers and industries worldwide. This work developed biodegradable films with antioxidant properties, using cassava starch combined with biomass or biomass extract of microalgae Heterochlorella luteoviridis and Dunaliella tertiolecta. The films were characterized by their physicochemical, mechanical, barrier, optical and antioxidant properties. The film with the best characteristics was used as salmon packaging aiming protection against lipid oxidation. In general, the addition of biomass increased films' solubility, biodegradability and opacity, while the films with the addition of biomass extract showed the lowest values of these parameters. The addition of biomass increased films' elongation, rupture, and reduced the tensile strength and Young's modulus. Conversely, the addition of microalgae extract caused the inverse effect on these properties. All films with microalgae showed higher antioxidant activity, evaluated by peroxide index, compared to the control ones. The film containing 2.0% of H. luteoviridis extract presented the lowest water vapor permeability and good mechanical characteristics, and was applied in salmon packaging. The selected packaging decreased fish moisture and delayed lipid oxidation evaluated by TBARS index. The results showed incorporation of microalgae biomass resulted in biodegradable and highly soluble films, making it difficult to apply in moist foods. The films containing microalgae extracts were suitable to be used in foods with high water content.

The effect of temperature and light intensity during cultivation of Chlorella miniata on antioxidant, anti-inflammatory potentials and phenolic compound accumulation

Abstract The purpose of this study was to see if the microalgae species Chlorella miniata possess an antioxidant and antiinflammatorypotential and to see if there is a correlation between the cultivation conditions and these potentials. For this purpose, cultivation of the algae under different growth conditions had been carried out; afterwards the soxhletextraction of the produced biomass had been completed. Lastly the assays of Trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant capacity (FARP), total antioxidant capacity (TAO), xanthine oxidase inhibition, and hyaluronidase inhibition were studied using extracts of microalgae obtained from the different cultivation parameters. It's important to mention that this was the first study using these assays on species of Chlorella miniata and the first that utilized the cultivation parameters on microalgae. The results were, 22,91 mg/g algae TEAC, 776,70 mg/g algae gallic acid equivalent of FRAP and 37,07% xanthine oxidase inhibition with a concentration of 10,5 mg algae per ml ethanol, 65,39% of hyaluronidase inhibition with a concentration of 0,9 mg algae per ml ethanol. The effects of the cultivation parameters on these assays and the Lc MS/MS analyses for various phenolic compounds in the extracts were also a part of the study.

The potential of waste microalgal hydrolysate for power generation in enzymatic fuel cell

Abstract The purpose of this study is to generate power by using the waste hydrolysate from microalgal extracts (AH), substrates of enzymatic fuel cell (EFC), and analyze the effects of microalgal hydrolysate containing a neutralizing agent on EFC. The effect of different dilute acids on extraction of microalgae was also investigated. The maximum concentration (∼5 g/L) of extraction was achieved for Chlorella pyrenoiudosa under the optimum conditions (2% hydrochloric acid and 100 g/L biomass loading). In order to investigate the effects of various neutralization agents used for AH on the EFC system, CV and EIS were investigated. Higher current and lower resistance values appeared during the neutralization using KOH. Maximum power density of 3637 μW/cm2 was obtained for the EFC system, 6.59 folds higher than the control. The result implies that AH used as a substrate has a significant influence on the power generation in the EFC system.

Challenges of Downstream Processing for the Production of Biodiesel from Microalgae

The continuous reliance on fossil fuels is unsustainable, due to the depletion of global reserves and the greenhouse gas emissions associated with their use. Therefore, there are vigorous research initiatives intended to develop renewable alternatives. Microalgae are a promising alternative for biodiesel production and have received increasing attention during the last few decades. However, is not yet sufficiently cost-effective to compete with petroleum-based conventional fuels. This happens essentially because of downstream processing – harvesting microalgae biomass and extraction of lipids are two of the most expensive processes from the overall process. Harvesting, drying, cell disruption, oil extraction and transesterification (into biodiesel) are highlighted processes in this review article. The techniques associated with each process present advantages and handicaps that are here discussed. Improvements that will directly affect the final production costs of microalgal biomass-based biofuels are also proposed.