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936 KiB

Open AccessArticle

Chemical Characterization of Enteromorpha prolifera Extract Obtained by Enzyme-Assisted Extraction and Its Influence on the Metabolic Activity of Caco-2

by Izabela Michalak, Agnieszka Dmytryk, Agnieszka Śmieszek and Krzysztof Marycz

Int. J. Mol. Sci. 2017, 18(3), 479; https://doi.org/10.3390/ijms18030479 - 23 Feb 2017

Cited by 14 | Viewed by 5346

Abstract

The green seaweed Enteromorpha prolifera was used as a feedstock for the production of enzymatic hydrolysate using cellulase. The selection of the conditions for enzymatic hydrolysis of the biomass was carried out for different enzyme doses and incubation periods. The obtained extract was [...] Read more.

The green seaweed Enteromorpha prolifera was used as a feedstock for the production of enzymatic hydrolysate using cellulase. The selection of the conditions for enzymatic hydrolysis of the biomass was carried out for different enzyme doses and incubation periods. The obtained extract was examined in terms of its multielemental composition, content of polyphenols and antibacterial properties (tested against Escherichia coli and Staphylococcus aureus). Additionally, its influence on the metabolic activity of human colon epithelial cells (Caco-2) was analyzed. The tested concentrations of extract using an in vitro model were 62.5, 125, 250, 500, 1000 and 2000 µg/mL. The hydrolysis yield in the most suitable experimental conditions (8-h process and 50 and 100 µL of cellulase) was 36%. Micro- and macroelements were poorly extracted from the algal biomass. Total phenolic content was 55 mg of gallic acid equivalent per 100 g of dry mass of extract. The cytotoxic effect of extracts, related to the inhibition of the metabolic activity of Caco-2, was noted only after 24 h. In turn, cultures of Caco-2 propagated with extracts for 72 h were characterized by significantly elevated metabolism (the concentration of extracts ranged from 62.5 to 1000 µg/mL, p < 0.05). Obtained results indicated the high biological activity of the prepared extracts; however, the observed effects did not occur in a dose-dependent manner. Full article

(This article belongs to the Special Issue Algae Based Bio-Renewable Energy for Sustainability)

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8663 KiB

Open AccessArticle

Changes of Photosynthetic Behaviors and Photoprotection during Cell Transformation and Astaxanthin Accumulation in Haematococcus pluvialis Grown Outdoors in Tubular Photobioreactors

by Litao Zhang, Fang Su, Chunhui Zhang, Fengying Gong and Jianguo Liu

Int. J. Mol. Sci. 2017, 18(1), 33; https://doi.org/10.3390/ijms18010033 - 26 Dec 2016

Cited by 54 | Viewed by 6448

Abstract

The cell transformation from green motile cells to non-motile cells and astaxanthin accumulation can be induced in the green alga Haematococcus pluvialis cultured outdoors. In the initial 3 d of incubation (cell transformation phase), light absorption and photosynthetic electron transport became more efficient. [...] Read more.

The cell transformation from green motile cells to non-motile cells and astaxanthin accumulation can be induced in the green alga Haematococcus pluvialis cultured outdoors. In the initial 3 d of incubation (cell transformation phase), light absorption and photosynthetic electron transport became more efficient. After five days of incubation (astaxanthin accumulation phase), the light absorption per active reaction center (ABS/RC) increased, but the efficiency of electron transport (ψ_o) and the quantum yield of electron transport (φ_Eo) decreased with increased time, indicating that the capacity of photosynthetic energy utilization decreased significantly during astaxanthin accumulation, leading to an imbalance between photosynthetic light absorption and energy utilization. It would inevitably aggravate photoinhibition under high light, e.g., at midday. However, the level of photoinhibition in H. pluvialis decreased as the incubation time increased, which is reflected by the fact that F_v/F_m determined at midday decreased significantly in the initial 3 d of incubation, but was affected very little after seven days of incubation, compared with that determined at predawn. This might be because the non-photochemical quenching, plastid terminal oxidase, photosystem I cyclic electron transport, defensive enzymes and the accumulated astaxanthin can protect cells against photoinhibition. Full article

(This article belongs to the Special Issue Algae Based Bio-Renewable Energy for Sustainability)

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3002 KiB

Open AccessArticle

Nitrogen Removal from Landfill Leachate by Microalgae

by Sérgio F. L. Pereira, Ana L. Gonçalves, Francisca C. Moreira, Tânia F. C. V. Silva, Vítor J. P. Vilar and José C. M. Pires

Int. J. Mol. Sci. 2016, 17(11), 1926; https://doi.org/10.3390/ijms17111926 - 17 Nov 2016

Cited by 45 | Viewed by 6492

Abstract

Landfill leachates result from the degradation of solid residues in sanitary landfills, thus presenting a high variability in terms of composition. Normally, these effluents are characterized by high ammoniacal-nitrogen (N–NH₄⁺) concentrations, high chemical oxygen demands and low phosphorus concentrations. The [...] Read more.

Landfill leachates result from the degradation of solid residues in sanitary landfills, thus presenting a high variability in terms of composition. Normally, these effluents are characterized by high ammoniacal-nitrogen (N–NH₄⁺) concentrations, high chemical oxygen demands and low phosphorus concentrations. The development of effective treatment strategies becomes difficult, posing a serious problem to the environment. Phycoremediation appears to be a suitable alternative for the treatment of landfill leachates. In this study, the potential of Chlorella vulgaris for biomass production and nutrients (mainly nitrogen and phosphorus) removal from different compositions of a landfill leachate was evaluated. Since microalgae also require phosphorus for their growth, different loads of this nutrient were evaluated, giving the following N:P ratios: 12:1, 23:1 and 35:1. The results have shown that C. vulgaris was able to grow in the different leachate compositions assessed. However, microalgal growth was higher in the cultures presenting the lowest N–NH₄⁺ concentration. In terms of nutrients uptake, an effective removal of N–NH₄⁺ and phosphorus was observed in all the experiments, especially in those supplied with phosphorus. Nevertheless, N–NO₃⁻ removal was considered almost negligible. These promising results constitute important findings in the development of a bioremediation technology for the treatment of landfill leachates. Full article

(This article belongs to the Special Issue Algae Based Bio-Renewable Energy for Sustainability)

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2945 KiB

Open AccessArticle

Microalgae Cultivation on Anaerobic Digestate of Municipal Wastewater, Sewage Sludge and Agro-Waste

by Luca Zuliani, Nicola Frison, Aleksandra Jelic, Francesco Fatone, David Bolzonella and Matteo Ballottari

Int. J. Mol. Sci. 2016, 17(10), 1692; https://doi.org/10.3390/ijms17101692 - 10 Oct 2016

Cited by 84 | Viewed by 8265

Abstract

Microalgae are fast-growing photosynthetic organisms which have the potential to be exploited as an alternative source of liquid fuels to meet growing global energy demand. The cultivation of microalgae, however, still needs to be improved in order to reduce the cost of the [...] Read more.

Microalgae are fast-growing photosynthetic organisms which have the potential to be exploited as an alternative source of liquid fuels to meet growing global energy demand. The cultivation of microalgae, however, still needs to be improved in order to reduce the cost of the biomass produced. Among the major costs encountered for algal cultivation are the costs for nutrients such as CO₂, nitrogen and phosphorous. In this work, therefore, different microalgal strains were cultivated using as nutrient sources three different anaerobic digestates deriving from municipal wastewater, sewage sludge or agro-waste treatment plants. In particular, anaerobic digestates deriving from agro-waste or sewage sludge treatment induced a more than 300% increase in lipid production per volume in Chlorella vulgaris cultures grown in a closed photobioreactor, and a strong increase in carotenoid accumulation in different microalgae species. Conversely, a digestate originating from a pilot scale anaerobic upflow sludge blanket (UASB) was used to increase biomass production when added to an artificial nutrient-supplemented medium. The results herein demonstrate the possibility of improving biomass accumulation or lipid production using different anaerobic digestates. Full article

(This article belongs to the Special Issue Algae Based Bio-Renewable Energy for Sustainability)

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360 KiB

Open AccessArticle

Biodiesel Production from Chlorella protothecoides Oil by Microwave-Assisted Transesterification

by Mustafa Ömer Gülyurt, Didem Özçimen and Benan İnan

Int. J. Mol. Sci. 2016, 17(4), 579; https://doi.org/10.3390/ijms17040579 - 22 Apr 2016

Cited by 31 | Viewed by 6025

Abstract

In this study, biodiesel production from microalgal oil by microwave-assisted transesterification was carried out to investigate its efficiency. Transesterification reactions were performed by using Chlorella protothecoides oil as feedstock, methanol, and potassium hydroxide as the catalyst. Methanol:oil ratio, reaction time and catalyst:oil ratio [...] Read more.

In this study, biodiesel production from microalgal oil by microwave-assisted transesterification was carried out to investigate its efficiency. Transesterification reactions were performed by using Chlorella protothecoides oil as feedstock, methanol, and potassium hydroxide as the catalyst. Methanol:oil ratio, reaction time and catalyst:oil ratio were investigated as process parameters affected methyl ester yield. 9:1 methanol/oil molar ratio, 1.5% KOH catalyst/oil ratio and 10 min were optimum values for the highest fatty acid methyl ester yield. Full article

(This article belongs to the Special Issue Algae Based Bio-Renewable Energy for Sustainability)

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Review

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345 KiB

Open AccessReview

Effect of Organic Solvents on Microalgae Growth, Metabolism and Industrial Bioproduct Extraction: A Review

by Krystian Miazek, Lukas Kratky, Radek Sulc, Tomas Jirout, Mario Aguedo, Aurore Richel and Dorothee Goffin

Int. J. Mol. Sci. 2017, 18(7), 1429; https://doi.org/10.3390/ijms18071429 - 4 Jul 2017

Cited by 87 | Viewed by 12832

Abstract

In this review, the effect of organic solvents on microalgae cultures from molecular to industrial scale is presented. Traditional organic solvents and solvents of new generation-ionic liquids (ILs), are considered. Alterations in microalgal cell metabolism and synthesis of target products (pigments, proteins, lipids), [...] Read more.

In this review, the effect of organic solvents on microalgae cultures from molecular to industrial scale is presented. Traditional organic solvents and solvents of new generation-ionic liquids (ILs), are considered. Alterations in microalgal cell metabolism and synthesis of target products (pigments, proteins, lipids), as a result of exposure to organic solvents, are summarized. Applications of organic solvents as a carbon source for microalgal growth and production of target molecules are discussed. Possible implementation of various industrial effluents containing organic solvents into microalgal cultivation media, is evaluated. The effect of organic solvents on extraction of target compounds from microalgae is also considered. Techniques for lipid and carotenoid extraction from viable microalgal biomass (milking methods) and dead microalgal biomass (classical methods) are depicted. Moreover, the economic survey of lipid and carotenoid extraction from microalgae biomass, by means of different techniques and solvents, is conducted. Full article

(This article belongs to the Special Issue Algae Based Bio-Renewable Energy for Sustainability)

554 KiB

Open AccessReview

A Holistic Approach to Managing Microalgae for Biofuel Applications

by Pau Loke Show, Malcolm S. Y. Tang, Dillirani Nagarajan, Tau Chuan Ling, Chien-Wei Ooi and Jo-Shu Chang

Int. J. Mol. Sci. 2017, 18(1), 215; https://doi.org/10.3390/ijms18010215 - 22 Jan 2017

Cited by 126 | Viewed by 11082

Abstract

Microalgae contribute up to 60% of the oxygen content in the Earth’s atmosphere by absorbing carbon dioxide and releasing oxygen during photosynthesis. Microalgae are abundantly available in the natural environment, thanks to their ability to survive and grow rapidly under harsh and inhospitable [...] Read more.

Microalgae contribute up to 60% of the oxygen content in the Earth’s atmosphere by absorbing carbon dioxide and releasing oxygen during photosynthesis. Microalgae are abundantly available in the natural environment, thanks to their ability to survive and grow rapidly under harsh and inhospitable conditions. Microalgal cultivation is environmentally friendly because the microalgal biomass can be utilized for the productions of biofuels, food and feed supplements, pharmaceuticals, nutraceuticals, and cosmetics. The cultivation of microalgal also can complement approaches like carbon dioxide sequestration and bioremediation of wastewaters, thereby addressing the serious environmental concerns. This review focuses on the factors affecting microalgal cultures, techniques adapted to obtain high-density microalgal cultures in photobioreactors, and the conversion of microalgal biomass into biofuels. The applications of microalgae in carbon dioxide sequestration and phycoremediation of wastewater are also discussed. Full article

(This article belongs to the Special Issue Algae Based Bio-Renewable Energy for Sustainability)

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252 KiB

Open AccessReview

Microalgal Cultivation in Secondary Effluent: Recent Developments and Future Work

by Junping Lv, Jia Feng, Qi Liu and Shulian Xie

Int. J. Mol. Sci. 2017, 18(1), 79; https://doi.org/10.3390/ijms18010079 - 1 Jan 2017

Cited by 47 | Viewed by 6064

Abstract

Eutrophication of water catchments and the greenhouse effect are major challenges in developing the global economy in the near future. Secondary effluents, containing high amounts of nitrogen and phosphorus, need further treatment before being discharged into receiving water bodies. At the same time, [...] Read more.

Eutrophication of water catchments and the greenhouse effect are major challenges in developing the global economy in the near future. Secondary effluents, containing high amounts of nitrogen and phosphorus, need further treatment before being discharged into receiving water bodies. At the same time, new environmentally friendly energy sources need to be developed. Integrating microalgal cultivation for the production of biodiesel feedstock with the treatment of secondary effluent is one way of addressing both issues. This article provides a comprehensive review of the latest progress in microalgal cultivation in secondary effluent to remove pollutants and accumulate lipids. Researchers have discovered that microalgae remove nitrogen and phosphorus effectively from secondary effluent, accumulating biomass and lipids in the process. Immobilization of appropriate microalgae, and establishing a consortium of microalgae and/or bacteria, were both found to be feasible ways to enhance pollutant removal and lipid production. Demonstrations of pilot-scale microalgal cultures in secondary effluent have also taken place. However there is still much work to be done in improving pollutants removal, biomass production, and lipid accumulation in secondary effluent. This includes screening microalgae, constructing the consortium, making use of flue gas and nitrogen, developing technologies related to microalgal harvesting, and using lipid-extracted algal residues (LEA). Full article

(This article belongs to the Special Issue Algae Based Bio-Renewable Energy for Sustainability)

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