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1127 KiB

Open AccessArticle

The Use of the Schizonticidal Agent Quinine Sulfate to Prevent Pond Crashes for Algal-Biofuel Production

by Chunyan Xu, Kangyan Wu, Steve W. Van Ginkel, Thomas Igou, Hwa Jong Lee, Aditya Bhargava, Rachel Johnston, Terry Snell and Yongsheng Chen

Int. J. Mol. Sci. 2015, 16(11), 27450-27456; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms161126035 - 17 Nov 2015

Cited by 15 | Viewed by 6380

Abstract

Algal biofuels are investigated as a promising alternative to petroleum fuel sources to satisfy transportation demand. Despite the high growth rate of algae, predation by rotifers, ciliates, golden algae, and other predators will cause an algae in open ponds to crash. In this [...] Read more.

Algal biofuels are investigated as a promising alternative to petroleum fuel sources to satisfy transportation demand. Despite the high growth rate of algae, predation by rotifers, ciliates, golden algae, and other predators will cause an algae in open ponds to crash. In this study, Chlorella kessleri was used as a model alga and the freshwater rotifer, Brachionus calyciflorus, as a model predator. The goal of this study was to test the selective toxicity of the chemical, quinine sulfate (QS), on both the alga and the rotifer in order to fully inhibit the rotifer while minimizing its impact on algal growth. The QS LC₅₀ for B. calyciflorus was 17 µM while C. kessleri growth was not inhibited at concentrations <25 µM. In co-culture, complete inhibition of rotifers was observed when the QS concentration was 7.7 µM, while algal growth was not affected. QS applications to produce 1 million gallons of biodiesel in one year are estimated to be $0.04/gallon or ~1% of Bioenergy Technologies Office’s (BETO) projected cost of $5/gge (gallon gasoline equivalent). This provides algae farmers an important tool to manage grazing predators in algae mass cultures and avoid pond crashes. Full article

(This article belongs to the Special Issue Microalgal Biotechnology)

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1607 KiB

Open AccessArticle

Novel Electrokinetic Microfluidic Detector for Evaluating Effectiveness of Microalgae Disinfection in Ship Ballast Water

by Myint Myint Maw, Junsheng Wang, Fabo Li, Jinhu Jiang, Younan Song and Xinxiang Pan

Int. J. Mol. Sci. 2015, 16(10), 25560-25575; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms161025560 - 26 Oct 2015

Cited by 15 | Viewed by 5528

Abstract

Ship ballast water treatment methods face many technical challenges. The effectiveness of every treatment method usually is evaluated by using large scale equipment and a large volume of samples, which involves time-consuming, laborious, and complex operations. This paper reports the development of a [...] Read more.

Ship ballast water treatment methods face many technical challenges. The effectiveness of every treatment method usually is evaluated by using large scale equipment and a large volume of samples, which involves time-consuming, laborious, and complex operations. This paper reports the development of a novel, simple and fast platform of methodology in evaluating the efficiency and the best parameters for ballast water treatment systems, particularly in chemical disinfection. In this study, a microfluidic chip with six sample wells and a waste well was designed, where sample transportation was controlled by electrokinetic flow. The performance of this microfluidic platform was evaluated by detecting the disinfection of Dunaliella salina (D. salina) algae in ballast water treated by sodium hypochlorite (NaClO) solution. Light-induced chlorophyll fluorescence (LICF) intensity was used to determine the viability of microalgae cells in the system, which can be operated automatically with the dimension of the detector as small as 50 mm × 24 mm × 5 mm. The 40 µL volume of sample solution was used for each treatment condition test and the validity of detection can be accomplished within about five min. The results show that the viability of microalgae cells under different treatment conditions can be determined accurately and further optimal treatment conditions including concentrations of NaClO and treatment time can also be obtained. These results can provide accurate evaluation and optimal parameters for ballast water treatment methods. Full article

(This article belongs to the Special Issue Microalgal Biotechnology)

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1328 KiB

Open AccessArticle

Use of Copper to Selectively Inhibit Brachionus calyciflorus (Predator) Growth in Chlorella kessleri (Prey) Mass Cultures for Algae Biodiesel Production

by Vishnupriya Pradeep, Steven W. Van Ginkel, Sichoon Park, Thomas Igou, Christine Yi, Hao Fu, Rachel Johnston, Terry Snell and Yongsheng Chen

Int. J. Mol. Sci. 2015, 16(9), 20674-20684; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms160920674 - 31 Aug 2015

Cited by 25 | Viewed by 6792

Abstract

A single Brachionus rotifer can consume thousands of algae cells per hour causing an algae pond to crash within days of infection. Thus, there is a great need to reduce rotifers in order for algal biofuel production to become reality. Copper can selectively [...] Read more.

A single Brachionus rotifer can consume thousands of algae cells per hour causing an algae pond to crash within days of infection. Thus, there is a great need to reduce rotifers in order for algal biofuel production to become reality. Copper can selectively inhibit rotifers in algae ponds, thereby protecting the algae crop. Differential toxicity tests were conducted to compare the copper sensitivity of a model rotifer—B. calyciflorus and an alga, C. kessleri. The rotifer LC₅₀ was <0.1 ppm while the alga was not affected up to 5 ppm Cu(II). The low pH of the rotifer stomach may make it more sensitive to copper. However, when these cultures were combined, a copper concentration of 1.5 ppm was needed to inhibit the rotifer as the alga bound the copper, decreasing its bioavailability. Copper (X ppm) had no effect on downstream fatty acid methyl ester extraction. Full article

(This article belongs to the Special Issue Microalgal Biotechnology)

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3445 KiB

Open AccessArticle

Assessing Transformations of Algal Organic Matter in the Long-Term: Impacts of Humification-Like Processes

by Maud Leloup, Virginie Pallier, Rudy Nicolau and Geneviève Feuillade-Cathalifaud

Int. J. Mol. Sci. 2015, 16(8), 18096-18110; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms160818096 - 05 Aug 2015

Cited by 11 | Viewed by 4984

Abstract

Algae and cyanobacteria are important contributors to the natural organic matter (NOM) of eutrophic water resources. The objective of this work is to increase knowledge on the modifications of algal organic matter (AOM) properties in the long term to anticipate blooms footprint in [...] Read more.

Algae and cyanobacteria are important contributors to the natural organic matter (NOM) of eutrophic water resources. The objective of this work is to increase knowledge on the modifications of algal organic matter (AOM) properties in the long term to anticipate blooms footprint in such aquatic environments. The production of AOM from an alga (Euglena gracilis) and a cyanobacteria (Microcystis aeruginosa) was followed up and characterized during the stationary phase and after one year and four months of cultivation, in batch experiments. Specific UV absorbance (SUVA) index, organic matter fractionation according to hydrophobicity and apparent molecular weight were combined to assess the evolution of AOM. A comparison between humic substances (HS) mainly derived from allochthonous origins and AOM characteristics was performed to hypothesize impacts of AOM transformation processes on the water quality of eutrophic water resources. Each AOM fraction underwent a specific evolution pattern, depending on its composition. Impacts of humification-like processes were predominant over release of biopolymers due to cells decay and led to an increase in the hydrophobic compounds part and molecular weights over time. However, the hydrophilic fraction remained the major fraction whatever the growth stage. Organic compounds generated by maturation of these precursors corresponded to large and aliphatic structures. Full article

(This article belongs to the Special Issue Microalgal Biotechnology)

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858 KiB

Open AccessArticle

A New Treatment Strategy for Inactivating Algae in Ballast Water Based on Multi-Trial Injections of Chlorine

by Jinyang Sun, Junsheng Wang, Xinxiang Pan and Haichao Yuan

Int. J. Mol. Sci. 2015, 16(6), 13158-13171; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms160613158 - 09 Jun 2015

Cited by 9 | Viewed by 6245

Abstract

Ships’ ballast water can carry aquatic organisms into foreign ecosystems. In our previous studies, a concept using ion exchange membrane electrolysis to treat ballast water has been proven. In addition to other substantial approaches, a new strategy for inactivating algae is proposed based [...] Read more.

Ships’ ballast water can carry aquatic organisms into foreign ecosystems. In our previous studies, a concept using ion exchange membrane electrolysis to treat ballast water has been proven. In addition to other substantial approaches, a new strategy for inactivating algae is proposed based on the developed ballast water treatment system. In the new strategy, the means of multi-trial injection with small doses of electrolytic products is applied for inactivating algae. To demonstrate the performance of the new strategy, contrast experiments between new strategies and routine processes were conducted. Four algae species including Chlorella vulgaris, Platymonas subcordiformis, Prorocentrum micans and Karenia mikimotoi were chosen as samples. The different experimental parameters are studied including the injection times and doses of electrolytic products. Compared with the conventional one trial injection method, mortality rate time (MRT) and available chlorine concentration can be saved up to about 84% and 40%, respectively, under the application of the new strategy. The proposed new approach has great potential in practical ballast water treatment. Furthermore, the strategy is also helpful for deep insight of mechanism of algal tolerance. Full article

(This article belongs to the Special Issue Microalgal Biotechnology)

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927 KiB

Open AccessArticle

Periodic CO₂ Dosing Strategy for Dunaliella salina Batch Culture

by Kezhen Ying, D. James Gilmour and William B. Zimmerman

Int. J. Mol. Sci. 2015, 16(5), 11509-11521; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms160511509 - 19 May 2015

Cited by 10 | Viewed by 5800

Abstract

A periodic CO₂ dosing strategy for D. salina 19/30 batch culture is proposed. A model of periodic CO₂ dosing including dosing time calculation, dosing interval estimation and final chlorophyll yield prediction was established. In experiments, 5% CO₂/95% N₂ [...] Read more.

A periodic CO₂ dosing strategy for D. salina 19/30 batch culture is proposed. A model of periodic CO₂ dosing including dosing time calculation, dosing interval estimation and final chlorophyll yield prediction was established. In experiments, 5% CO₂/95% N₂ gas was periodically dosed into D. salina culture. Two different gas dosing flow rates were tested. The corresponding dosing time for each flow rate was estimated via the model (10 min·d⁻¹ for 0.7 L·min⁻¹ and 36 min·d⁻¹ for 0.3 L·min⁻¹). Daily pH measurements showed that the pH of these cultures dosed periodically was always kept between 7.5 and 9.5, which highlights that periodic gas supply can maintain a suitable range of pH for microalgal growth without expensive buffers. Notably the culture dosed for set daily intervals was seen to have similar growth to the culture supplied constantly, but with much higher CO₂ capture efficiency (11%–18%) compared to continuous dosing (0.25%). It shows great potential for using periodic gas supply to reduce cost, wasted gas and energy use. Full article

(This article belongs to the Special Issue Microalgal Biotechnology)

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757 KiB

Open AccessArticle

Mutation Breeding of Extracellular Polysaccharide-Producing Microalga Crypthecodinium cohnii by a Novel Mutagenesis with Atmospheric and Room Temperature Plasma

by Bin Liu, Zheng Sun, Xiaonian Ma, Bo Yang, Yue Jiang, Dong Wei and Feng Chen

Int. J. Mol. Sci. 2015, 16(4), 8201-8212; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms16048201 - 13 Apr 2015

Cited by 44 | Viewed by 7383

Abstract

Extracellular polysaccharides (EPS) produced by marine microalgae have the potential to be used as antioxidants, antiviral agents, immunomodulators, and anti-inflammatory agents. Although the marine microalga Crypthecodinium cohnii releases EPS during the process of docosahexaenoic acid (DHA) production, the yield of EPS remains relatively [...] Read more.

Extracellular polysaccharides (EPS) produced by marine microalgae have the potential to be used as antioxidants, antiviral agents, immunomodulators, and anti-inflammatory agents. Although the marine microalga Crypthecodinium cohnii releases EPS during the process of docosahexaenoic acid (DHA) production, the yield of EPS remains relatively low. To improve the EPS production, a novel mutagenesis of C. cohnii was conducted by atmospheric and room temperature plasma (ARTP). Of the 12 mutants obtained, 10 mutants exhibited significantly enhanced EPS yield on biomass as compared with the wild type strain. Among them, mutant M7 was the best as it could produce an EPS volumetric yield of 1.02 g/L, EPS yield on biomass of 0.39 g/g and EPS yield on glucose of 94 mg/g, which were 33.85%, 85.35% and 57.17% higher than that of the wild type strain, respectively. Results of the present study indicated that mutagenesis of the marine microalga C. cohnii by ARTP was highly effective leading to the high-yield production of EPS. Full article

(This article belongs to the Special Issue Microalgal Biotechnology)

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3416 KiB

Open AccessArticle

Combined Enzymatic and Mechanical Cell Disruption and Lipid Extraction of Green Alga Neochloris oleoabundans

by Dongqin Wang, Yanqun Li, Xueqiong Hu, Weimin Su and Min Zhong

Int. J. Mol. Sci. 2015, 16(4), 7707-7722; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms16047707 - 07 Apr 2015

Cited by 76 | Viewed by 8690

Abstract

Microalgal biodiesel is one of the most promising renewable fuels. The wet technique for lipids extraction has advantages over the dry method, such as energy-saving and shorter procedure. The cell disruption is a key factor in wet oil extraction to facilitate the intracellular [...] Read more.

Microalgal biodiesel is one of the most promising renewable fuels. The wet technique for lipids extraction has advantages over the dry method, such as energy-saving and shorter procedure. The cell disruption is a key factor in wet oil extraction to facilitate the intracellular oil release. Ultrasonication, high-pressure homogenization, enzymatic hydrolysis and the combination of enzymatic hydrolysis with high-pressure homogenization and ultrasonication were employed in this study to disrupt the cells of the microalga Neochloris oleoabundans. The cell disruption degree was investigated. The cell morphology before and after disruption was assessed with scanning and transmission electron microscopy. The energy requirements and the operation cost for wet cell disruption were also estimated. The highest disruption degree, up to 95.41%, assessed by accounting method was achieved by the combination of enzymatic hydrolysis and high-pressure homogenization. A lipid recovery of 92.6% was also obtained by the combined process. The combined process was found to be more efficient and economical compared with the individual process. Full article

(This article belongs to the Special Issue Microalgal Biotechnology)

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727 KiB

Open AccessArticle

Rapid Characterization of Fatty Acids in Oleaginous Microalgae by Near-Infrared Spectroscopy

by Bin Liu, Jin Liu, Tianpeng Chen, Bo Yang, Yue Jiang, Dong Wei and Feng Chen

Int. J. Mol. Sci. 2015, 16(4), 7045-7056; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms16047045 - 27 Mar 2015

Cited by 14 | Viewed by 6422

Abstract

The key properties of microalgal biodiesel are largely determined by the composition of its fatty acid methyl esters (FAMEs). The gas chromatography (GC) based techniques for fatty acid analysis involve energy-intensive and time-consuming procedures and thus are less suitable for high-throughput screening applications. [...] Read more.

The key properties of microalgal biodiesel are largely determined by the composition of its fatty acid methyl esters (FAMEs). The gas chromatography (GC) based techniques for fatty acid analysis involve energy-intensive and time-consuming procedures and thus are less suitable for high-throughput screening applications. In the present study, a novel quantification method for microalgal fatty acids was established based on the near-infrared spectroscopy (NIRS) technique. The lyophilized cells of oleaginous Chlorella containing different contents of lipids were scanned by NIRS and their fatty acid profiles were determined by GC-MS. NIRS models were developed based on the chemometric correlation of the near-infrared spectra with fatty acid profiles in algal biomass. The optimized NIRS models showed excellent performances for predicting the contents of total fatty acids, C16:0, C18:0, C18:1 and C18:3, with the coefficient of determination (R²) being 0.998, 0.997, 0.989, 0.991 and 0.997, respectively. Taken together, the NIRS method established here bypasses the procedures of cell disruption, oil extraction and transesterification, is rapid, reliable, and of great potential for high-throughput applications, and will facilitate the screening of microalgal mutants and optimization of their growth conditions for biodiesel production. Full article

(This article belongs to the Special Issue Microalgal Biotechnology)

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Review

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848 KiB

Open AccessReview

Effect of Metals, Metalloids and Metallic Nanoparticles on Microalgae Growth and Industrial Product Biosynthesis: A Review

by Krystian Miazek, Waldemar Iwanek, Claire Remacle, Aurore Richel and Dorothee Goffin

Int. J. Mol. Sci. 2015, 16(10), 23929-23969; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms161023929 - 09 Oct 2015

Cited by 166 | Viewed by 18453

Abstract

Microalgae are a source of numerous compounds that can be used in many branches of industry. Synthesis of such compounds in microalgal cells can be amplified under stress conditions. Exposure to various metals can be one of methods applied to induce cell stress [...] Read more.

Microalgae are a source of numerous compounds that can be used in many branches of industry. Synthesis of such compounds in microalgal cells can be amplified under stress conditions. Exposure to various metals can be one of methods applied to induce cell stress and synthesis of target products in microalgae cultures. In this review, the potential of producing diverse biocompounds (pigments, lipids, exopolymers, peptides, phytohormones, arsenoorganics, nanoparticles) from microalgae cultures upon exposure to various metals, is evaluated. Additionally, different methods to alter microalgae response towards metals and metal stress are described. Finally, possibilities to sustain high growth rates and productivity of microalgal cultures in the presence of metals are discussed. Full article

(This article belongs to the Special Issue Microalgal Biotechnology)

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