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Daniel P Kiesenhofer, Silvia Fluch
Over the past decades, interest in microalgae has grown exponentially. Especially industrial applications, such as biodiesel production from microalgae were hyped in the early 2000s. But since the first attempts to commercialize microalgae derived products for energy applications, only a few developments made it to the market. What is hindering the full exploitation of this valuable resource for food, feed, and energy applications? This opinion paper reflects on the state of the art of industrial microalgae culturing and the knowledge gaps that still need to be filled jointly by academia and industry...
December 6, 2017: FEMS Microbiology Letters
Ehsan Sarayloo, Salim Simsek, Yigit Sabri Unlu, Gul Cevahir, Can Erkey, Ibrahim Halil Kavakli
In this study, we applied a second round of random mutagenesis using ethyl methanesulfonate to further increase the lipid productivity of a Chlorella vulgaris mutant strain. We generated a mutant (UV715-EMS25) with a lipid content and biomass that were respectively 67% and 35% higher than those of the wild type (WT). The highest achieved lipid productivity in UV715-EMS25 was 91 mg L-1 day-1. Gas chromatography-mass spectrophotometric analysis revealed that the fatty acid methyl ester content of the mutant was 3...
December 2, 2017: Bioresource Technology
Katharina Anna Lindlbauer, Hans Marx, Michael Sauer
Background: In their quest for sustainable development and effective management of greenhouse gas emissions, our societies pursue a shift away from fossil-based resources towards renewable resources. With 95% of our current transportation energy being petroleum based, the application of alternative, carbon-neutral products-among them biodiesel-is inevitable. In order to enhance the cost structure of biodiesel biorefineries, the valorization of the crude glycerol waste stream into high-value platform chemicals is of major importance...
2017: Biotechnology for Biofuels
Ramachandran Sivaramakrishnan, Aran Incharoensakdi
The application of ultrasound in biodiesel production has recently emerged as a novel technology. Ultrasound treatment enhances the mass transfer characteristics leading to the increased reaction rate with short reaction time and potentially reduces the production cost. In this review, application of ultrasound-assisted biodiesel production using acid, base and enzyme catalysts is presented. A critical assessment of the current status of ultrasound in biodiesel production was discussed with the emphasis on using ultrasound for efficient microalgae biodiesel production...
November 29, 2017: Bioresource Technology
Venkateswara R Naira, Debasish Das, Soumen K Maiti
A cylindrical membrane photobioreactor with high CO2 mass transfer coefficient was designed and installed under customized unidirectional lighting. Combinatorial effect of light and CO2 on the growth of Chlorella sp. FC2 IITG was studied and an optimal CO2 supply without pH control strategy was developed under diurnal light similar to sunlight (17-2000-17 µE m-2 s-1). Unprecedentedly, broad range of saturated light levels (700-1500 µE m-2 s-1), reversible photoinhibition, no pH control requirement and dark-phase growth were noticed altogether in the strain...
December 2, 2017: Bioresource Technology
Weiwei Zhang, Huixia Yang, Wanyi Liu, Na Wang, Xiaoqi Yu
Lipases are the most widely employed enzymes in commercial industries. The catalytic mechanism of most lipases involves a step called "interfacial activation". As interfacial activation can lead to a significant increase in catalytic activity, it is of profound importance in developing lipase immobilization methods. To obtain a potential biocatalyst for industrial biodiesel production, an effective strategy for enhancement of catalytic activity and stability of immobilized lipase was developed. This was performed through the combination of interfacial activation with hybrid magnetic cross-linked lipase aggregates...
December 7, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Loris Fossier Marchan, Kim J Lee Chang, Peter D Nichols, Jane L Polglase, Wilfrid J Mitchell, Tony Gutierrez
Thraustochytrids isolated from hot tropical and sub-tropical waters have been well studied for DHA and biodiesel production in the last decades. However, little research has been performed on the oils of cold water thraustochytrids, in particular from the North Sea region. In this study, thraustochytrid strains from British waters showed high relative levels of omega-3 long-chain (≥C20) polyunsaturated fatty acids (LC-PUFA), including docosahexaenoic acid (DHA, 22:6ω3). The relative levels of DHA (as % of total fatty acids, TFA) in the different British strains are hitherto amongst the highest recorded from any thraustochytrid screening study, with strain TL18 reaching up to 67% DHA in modified Glucose-Yeast Extract-Peptone (GYP) medium...
2017: Journal of Applied Phycology
Huixin Lin, Yuan Kun Lee
Genetic engineering of microalgae to accumulate high levels of medium-chain-length fatty acids (MCFAs) represents an attractive strategy to improve the quality of microalgae-based biodiesel, but it has thus far been least successful. We demonstrate that one limitation is the availability of fatty acyl-acyl carrier protein (ACP) substrate pool for acyl-ACP thioesterase (TE). A combinational expression platform that involved plant lauric acid-biased TE (C12TE) and MCFA-specific ketoacyl-ACP synthase (KASIV) increased lauric acid (C12:0) and myristic acid (C14:0) accumulation by almost sevenfold and fourfold, respectively, compared with native strain...
2017: Journal of Applied Phycology
Philip Kenny, Kevin J Flynn
Algal biofuels have been offered as an alternative to fossil fuels, based on claims that microalgae can provide a highly productive source of compounds as feedstocks for sustainable transport fuels. Life cycle analyses identify algal productivity as a critical factor affecting commercial and environmental viability. Here, we use mechanistic modelling of the biological processes driving microalgal growth to explore optimal production scenarios in an industrial setting, enabling us to quantify limits to algal biofuels potential...
2017: Journal of Applied Phycology
Mi-Ae Han, Seong-Joo Hong, Z-Hun Kim, Byung-Kwan Cho, Hookeun Lee, Hyung-Kyoon Choi, Choul-Gyun Lee
Lipids in microalgae are energy-rich compounds and considered as an attractive feedstock for biodiesel production. To redirect carbon flux from competing pathways to the fatty acid synthesis pathway of Tetraselmis sp., we used three types of chemical inhibitors, which can block the starch synthesis pathway or photorespiration, under nitrogen-sufficient and nitrogen-deficient conditions. The starch synthesis pathway in chloroplasts and the cytosol can be inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 1,2-cyclohexanediamine tetra acetic acid, respectively...
December 8, 2017: Journal of Microbiology and Biotechnology
Chunhua Xin, Min M Addy, Jinyu Zhao, Yanling Cheng, Yiwei Ma, Shiyu Liu, Dongyan Mu, Yuhuan Liu, Paul Chen, Roger Ruan
Combining wastewater treatment and biofuel production is considered the cost-effective way for better waste remediation and lowering the environmental impact for biofuel production. In this study, an innovative integrated system incorporating sludge, scum and centrate treatment and biofuel production was developed. A comprehensive techno-economic analysis was conducted to evaluate the technology and economic feasibility of the integrated system with the consideration of biofuel production, wastewater treatment improvement, tax credits, carbon credit, and coproducts utilization...
November 14, 2017: Bioresource Technology
Lijie Zhang, Haiyan Pei, Shuaiqi Chen, Liqun Jiang, Qingjie Hou, Zhigang Yang, Ze Yu
Salinity stress has been verified to be a successful approach to enhance lipid production in high-starch marine algae, and salinity-induced carbon flow switching has been proposed as an algal response specific to brackish water. With the aim of testing this assumption, Chlorella sorokiniana SDEC-18, a low-starch freshwater alga, was grown in BG11 medium with NaCl addition at various concentrations (0, 2, 5, 10, 20, and 30 g/L). The results showed that salinity stress promoted carbon redistribution and starch conversion to lipid...
November 23, 2017: Bioresource Technology
Ja Kyong Ko, Sun-Mi Lee
Cellulosic fuels are expected to have great potential industrial applications in the near future, but they still face technical challenges to become cost-competitive fuels, thus presenting many opportunities for improvement. The economical production of viable biofuels requires metabolic engineering of microbial platforms to convert cellulosic biomass into biofuels with high titers and yields. Fortunately, integrating traditional and novel engineering strategies with advanced engineering toolboxes has allowed the development of more robust microbial platforms, thus expanding substrate ranges...
November 27, 2017: Current Opinion in Biotechnology
Fabrizio Di Caprio, Francesca Pagnanelli, Rene H Wijffels, Douwe Van der Veen
Much of our current knowledge of microbial growth is obtained from studies at a population level. Driven by the realization that processes which operate within a population might influence a population's behavior, we sought to better understand Acutodesmus obliquus (formerly Scenedesmus obliquus) physiology at the cellular level. In this work, an accurate pre-treatment method to quantitatively obtain single cells of A. obliquus, a coenobia-forming alga, is described. These single cells were examined by flow cytometry for TAG, chlorophyll, and protein content, and their cell sizes were recorded by coulter counter...
December 1, 2017: Journal of Phycology
Muneeswaran Ramakrishnan, Thansekhar Maruthu Rathinam, Karthickeyan Viswanathan
In the present experimental analysis, two non-edible oils namely neem oil and pumpkin seed oil were considered. They are converted into respective biodiesels namely neem oil methyl ester (B1) and pumpkin seed oil methyl ester (B2) through transesterification process and their physical and chemical properties were examined using ASTM standards. Diesel was used as a baseline fuel in Kirloskar TV1 model direct injection four stroke diesel engine. A fuel preheater was designed and fabricated to operate at various temperatures (60, 70, and 80 °C)...
December 1, 2017: Environmental Science and Pollution Research International
Sidnei C Santos, Martin G Liebensteiner, Antonie H van Gelder, Mauricio R Dimitrov, Paulo F Almeida, Cristina M Quintella, Alfons J M Stams, Irene Sánchez-Andrea
Glycerol is a main co-product of biodiesel production. Crude glycerol may serve as a cheap and attractive substrate in biotechnological applications, e.g. for the production of valuable chemicals or as an electron donor for reduction processes. In this work, sulfate reduction with glycerol was studied at neutral and acidic pH using bioreactor sludge samples and Tinto River sediments as a source of inoculum, respectively. Communities of sulfate-reducing bacteria (SRB) and fermentative bacteria were co-enriched at both pH values...
November 29, 2017: Journal of General and Applied Microbiology
Ifeoluwa A Bamgbose, Todd A Anderson
Biodiesel is an alternative fuel that is gradually replacing petroleum-based diesel use. Although biodiesel is considered friendlier to the environment, the potential toxic effects of biodiesel to aquatic organisms are still uncertain due to the wide range of feedstocks used to generate the fuel. The aquatic cladoceran Daphnia magna (D. magna) has been commonly used as a lethal and/or sub-lethal toxicological model organism in ecological risk assessments for contaminated water environments. In this work, we evaluated whether significant differences exist in the sensitivity of freshwater aquatic life to different biodiesels...
November 29, 2017: Environmental Science and Pollution Research International
Kai Li, Yanli Fan, Yaojia He, Leping Zeng, Xiaotao Han, Yunjun Yan
Biodiesel production using immobilized lipase as a biocatalyst is a promising process. The performance of immobilized lipase is mainly determined by supporting materials and immobilization method. To avoid the shortcomings of adsorption and covalent bonding methods, in this study, we developed a novel heterofunctional carrier of being strengthened anion exchange and weakened covalent binding to avoid activity loss and improve operational stability of the immobilized lipase. 2,3-epoxypropyltrimethylammonium chloride with epoxy and quaternary ammonium group and glutaraldehyde were grafted onto aminated magnetic nanoparticles (AMNPs) to generate a new matrix, named GEAMNP...
November 28, 2017: Scientific Reports
Mina Mehregan, Mohammad Moghiman
The present work submits an investigation about the effect of urea injection parameters on NOx emissions from a four-stroke four-cylinder diesel engine fueled with B20 blended biodiesel. An L9(34) Taguchi orthogonal array was used to design the test plan. The results reveal that increasing urea concentration leads to lower NOx emissions. Urea flow rate increment has the same influence on NOx emission. The same result is obtained by an increase in spray angle. Also, according to the analysis of variance (ANOVA), urea concentration and then urea flow rate are the most effective design parameters on NOx emissions, while spray angle and mixing length have less influence on this pollutant emission...
November 27, 2017: Environmental Science and Pollution Research International
Renata Gudiukaite, Alisa Gricajeva
Genetic fusion of coding ORFs or connection of proteins in a post translational process are rather novel techniques to build products called fusion proteins that possess combined characteristics of their parental biomolecules. This attractive strategy used to create new enzymes not only diversifies their functionality by improving thermostability, thermo- and catalytic activity, substrate specificity, regio- or enantio-selectivity but also facilitates their purification and increases their yield. Many examples of microbial synthetic fusion biocatalysts are associated with fused enzymes that are involved in biomass degradation...
November 27, 2017: World Journal of Microbiology & Biotechnology
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