Promising Source Of Biofuels Research Articles

Oleaginous fungi: a promising source of biofuels and nutraceuticals with enhanced lipid production strategies.

Oleaginous fungi have attracted a great deal of interest for their potency to accumulate high amounts of lipids (more than 20% of biomass dry weight) and polyunsaturated fatty acids (PUFAs), which have a variety of industrial and biological applications. Lipids of plant and animal origin are related to some restrictions and thus lead to attention towards oleaginous microorganisms as reliable substitute resources. Lipids are traditionally biosynthesized intra-cellularly and involved in the building structure of a variety of cellular compartments. In oleaginous fungi, under certain conditions of elevated carbon ratio and decreased nitrogen in the growth medium, a change in metabolic pathway occurred by switching the whole central carbon metabolism to fatty acid anabolism, which subsequently resulted in high lipid accumulation. The present review illustrates the bio-lipid structure, fatty acid classes and biosynthesis within oleaginous fungi with certain key enzymes, and the advantages of oleaginous fungi over other lipid bio-sources. Qualitative and quantitative techniques for detecting the lipid accumulation capability of oleaginous microbes including visual, and analytical (convenient and non-convenient) were debated. Factors affecting lipid production, and different approaches followed to enhance the lipid content in oleaginous yeasts and fungi, including optimization, utilization of cost-effective wastes, co-culturing, as well as metabolic and genetic engineering, were discussed. A better understanding of the oleaginous fungi regarding screening, detection, and maximization of lipid content using different strategies could help to discover new potent oleaginous isolates, exploit and recycle low-cost wastes, and improve the efficiency of bio-lipids cumulation with biotechnological significance.

Economic and environmental bottlenecks in the industrial‐scale production of lipid‐derived biofuels from oleaginous yeasts: A review of the current trends and future prospects

AbstractConcerns about climate change and the reliance on fossil fuel reserves have motivated researchers to identify new renewable sources of energy. Biomass holds the potential to replace fossil‐derived products with biofuels and bio‐based chemicals. Plant‐derived lipids are promising sources of biofuels; however, the production of plant oil often leads to the release of massive amounts of carbon dioxide due to deforestation and land‐use change. The production of biofuels via plant oils (such as soybean) also competes with food production and in turn, impacts biodiversity. To mitigate these issues, the production of lipids from oleaginous yeasts could be an excellent alternative by incorporating these microbes into biorefineries utilizing agricultural or forest residues. Eventually, these microbial lipids could be potential sources for producing lipid‐derived biofuels. However, the current conventional methods for the production and recovery of lipids from oleaginous microbes suffer from economic and ecological challenges that affect its industrial‐scale expansion. This review highlights the major economic and environmental bottlenecks for the production of lipid‐derived biofuels from oleaginous yeasts. It also provides perspectives on the strategies that could be adapted on economic and ecological fronts to assist the expansion of the production of microbial lipid‐derived biofuels at an industrial scale.

Increasing lipid production in Chlamydomonas reinhardtii through genetic introduction for the overexpression of glyceraldehyde-3-phosphate dehydrogenase.

Microalgae, valued for their sustainability and CO2 fixation capabilities, are emerging as promising sources of biofuels and high-value compounds. This study aimed to boost lipid production in C. reinhardtii by overexpressing chloroplast glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a key enzyme in the Calvin cycle and glycolysis, under the control of a nitrogen-inducible NIT1 promoter, to positively impact overall carbon metabolism. The standout transformant, PNG#7, exhibited significantly increased lipid production under nitrogen starvation, with biomass rising by 44% and 76% on days 4 and 16, respectively. Fatty acid methyl ester (FAME) content in PNG#7 surged by 2.4-fold and 2.1-fold, notably surpassing the wild type (WT) in lipid productivity by 3.4 and 3.7 times on days 4 and 16, respectively. Transcriptome analysis revealed a tenfold increase in transgenic GAPDH expression and significant upregulation of genes involved in fatty acid and triacylglycerol synthesis, especially the gene encoding acyl-carrier protein gene (ACP, Cre13. g577100. t1.2). In contrast, genes related to cellulose synthesis were downregulated. Single Nucleotide Polymorphism (SNP)/Indel analysis indicated substantial DNA modifications, which likely contributed to the observed extensive transcriptomic and phenotypic changes. These findings suggest that overexpressing chloroplast GAPDH, coupled with genetic modifications, effectively enhances lipid synthesis in C. reinhardtii. This study not only underscores the potential of chloroplast GAPDH overexpression in microalgal lipid synthesis but also highlights the expansive potential of metabolic engineering in microalgae for biofuel production.

Integrating genome-wide association study with transcriptomic data to predict candidate genes influencing Brassica napus root and biomass-related traits under low phosphorus conditions

BackgroundRapeseed (Brassica napus L.) is an essential source of edible oil and livestock feed, as well as a promising source of biofuel. Breeding crops with an ideal root system architecture (RSA) for high phosphorus use efficiency (PUE) is an effective way to reduce the use of phosphate fertilizers. However, the genetic mechanisms that underpin PUE in rapeseed remain elusive. To address this, we conducted a genome-wide association study (GWAS) in 327 rapeseed accessions to elucidate the genetic variability of 13 root and biomass traits under low phosphorus (LP; 0.01 mM P +). Furthermore, RNA-sequencing was performed in root among high/low phosphorus efficient groups (HP1/LP1) and high/low phosphorus stress tolerance groups (HP2/LP2) at two-time points under control and P-stress conditions.ResultsSignificant variations were observed in all measured traits, with heritabilities ranging from 0.47 to 0.72, and significant correlations were found between most of the traits. There were 39 significant trait–SNP associations and 31 suggestive associations, which integrated into 11 valid quantitative trait loci (QTL) clusters, explaining 4.24–24.43% of the phenotypic variance observed. In total, RNA-seq identified 692, 1076, 648, and 934 differentially expressed genes (DEGs) specific to HP1/LP1 and HP2/LP2 under P-stress and control conditions, respectively, while 761 and 860 DEGs common for HP1/LP1 and HP2/LP2 under both conditions. An integrated approach of GWAS, weighted co-expression network, and differential expression analysis identified 12 genes associated with root growth and development under LP stress. In this study, six genes (BnaA04g23490D, BnaA09g08440D, BnaA09g04320D, BnaA09g04350D, BnaA09g04930D, BnaA09g09290D) that showed differential expression were identified as promising candidate genes for the target traits.Conclusion11 QTL clusters and 12 candidate genes associated with root and development under LP stress were identified in this study. Our study's phenotypic and genetic information may be exploited for genetic improvement of root traits to increase PUE in rapeseed.

Multifarious extraction methodologies for ameliorating lipid recovery from algae

Amongst the current alternatives, algae were proven to be a promising source of biofuel, which is renewable and capable of meeting world demand for transportation fuels. However, a suitable lipid extraction method that efficiently releases the lipids from different algal strains remains a bottleneck. The multifarious pretreatment methods are prevalent in this field of lipid extraction, and therefore, this article has critically reviewed the various lipid extraction methods for ameliorating the lipid yield from algae, irrespective of the strains/species. Physical, mechanical, and chemical are the different types of pretreatment methods. In this review, methodologies such as homogenization, sonication, Soxhlet extraction, microwave treatment, and bead-beating, have been studied in detail and are the most commonly used methods for lipid extraction. Specific advanced/emerging processes such as supercritical CO2 extraction, ionic liquid, and CO2 switchable solvent-based algal lipid extraction are yet to be demonstrated at pilot-scale, though promising. The extraction of lipids has to be financially conducive, environmentally sustainable, and industrially applicable for further conversion into biodiesel. Hence, this paper discusses variable pretreatment for lipid extraction and imparts a comparative analysis to elect an efficient, economically sound lipid extraction method for pilot-scale biodiesel production.

Detailed kinetics for anisole oxidation under various range of operating conditions

Biofuels produced from biomass are considered a potential source of renewable energy that can be used as an alternative to fossil fuels. Lignocellulosic biomass produces phenolic compounds like anisole which is a promising source of biofuel. Anisole (methoxybenzene) is an aromatic compound and has advantageous features as a drop-in fuel in combustion devices. In this work, a detailed mechanism of anisole is generated to numerically study the oxidation of this fuel at engine-relevant conditions. The comprehensive model is developed using the reaction mechanism generator (RMG). The mechanism is used for calculating laminar burning speed (LBS), ignition delay time (IDT), and species concentration, to compare with experimental data. Sensitivity and reaction path flux analyses are considered in evaluating the mechanism. Important reactions are identified which have a very significant effect on the prediction of the model. The rate of these important reactions is studied from the literature to make the mechanism perform well for a wide range of conditions. The final mechanism named PCRL-Mech3 contains 466 species and 3691 reactions. PCRL-Mech3 shows a successful validation of IDT at both rapid compression machine (RCM) and shock tube (ST) experiment which cover temperatures of 800–1600 K and pressures of 10–40 atm. Validation of LBS is performed using recently published work by the same group. This data enables the opportunity to evaluate and improve PCRL-Mech3 for a wider range of LBS conditions (i.e., 0.5–5.5 atm, 460–550 K, and 0.8–1.4 equivalence ratio). Species concentration of anisole and stable intermediates of final mechanism match reasonably well with different jet stirred reactor experiments. Compared with the literature, the mechanism can show improved prediction over a larger span of engine-relevant conditions that also helps to identify the regimes where more experimental and numerical improvement is required.

THE EXTRACTION OF OIL FROM Nannochloropsis sp. MICROALGAE USING ULTRASONIC AND FERMENTATION AS CELL DISRUPTION

Algae are a promising source of biofuel but claims about their lipid content can be ambiguous becauseextraction methods vary and lipid quantitation often does not distinguish between particular lipid classes.One of algae types that meet this condition is Nannochloropsis sp. Two different cell disruption methods,i.eultrasonic and fermentation followed by maceration extraction using a mixture of ethanol/hexane (1:1, v/v)as a solvent extraction were studied for their effectiveness in extraction of algae lipids from Nannochloropsissp. Contact time and amplitude were varied in ultrasonic process. Hydrolysis treatment was varied infermentation process, i.e Dillute Acid Pretreatment (DAP) hydrolysis, enzymatic hydrolysis and DAP withenzymatic hydrolysis. The result showed that ultrasonic process followed by maceration extraction wasmore effective for Nannochloropsis sp. lipid extraction. The most ideal treatment was at amplitude 40%and contact time 5 minutes with lipid content of 63.59% of dry weight.

Secretomics: a biochemical footprinting tool for developing microalgal cultivation strategies.

Microalgae offer a promising source of biofuel and a wide array of high-value biomolecules. Large-scale cultivation of microalgae at low density poses a significant challenge in terms of water management. High-density microalgae cultivation, however, can be challenging due to biochemical changes associated with growth dynamics. Therefore, there is a need for a biomarker that can predict the optimum density for high biomass cultivation. A locally isolated microalga Cyanobacterium aponinum CCC734 was grown with optimized nitrogen and phosphorus in the ratio of 12:1 for sustained high biomass productivity. To understand density-associated bottlenecks secretome dynamics were monitored at biomass densities from 0.6 ± 0.1 to 7 ± 0.1g/L (2 to 22 OD) in batch mode. Liquid chromatography coupled with mass spectrometry identified 880 exometabolites in the supernatant of C. aponinum CCC734. The PCA analysis showed similarity between exometabolite profiles at low (4 and 8 OD) and mid (12 and 16 OD), whereas distinctly separate at high biomass concentrations (20 and 22 OD). Ten exometabolites were selected based on their role in influencing growth and are specifically present at low, mid, and high biomass concentrations. Taking cues from secretome dynamics, 5.0 ± 0.5g/L biomass concentration (16 OD) was optimal for C. aponinum CCC734 cultivation. Further validation was performed with a semi-turbidostat mode of cultivation for 29days with a volumetric productivity of 1.0 ± 0.2g/L/day. The secretomes-based footprinting tool is the first comprehensive growth study of exometabolite at the molecular level at variable biomass densities. This tool may be utilized in analyzing and directing microalgal cultivation strategies and reduction in overall operating costs.

Impacts of applied voltage on forward osmosis process harvesting microalgae: Filtration behaviors and lipid extraction efficiency

Microalgae are promising source of biofuels, while harvesting process is the obstacle for the further development. Herein, a treatment system that combined electrochemical process with forward osmosis (FO) membrane filtration process was developed to achieve microalgae harvesting. The conductive FO membranes were used as both electrode materials and basic separation system. With −5 V electric field being applied, 57.6% of reduction in water flux loss was observed, while microalgae recovery efficiency increased by 17.3%. The lipid content also increased to nearly 38%. Meanwhile, the inevitable reverse diffusion of solutes in the FO process and the concentration process of the microalgae solution increased the salinity of the microalgae solution, which is generally regarded as an obstacle for the application of FO. However, in the electrically-assisted FO system, it not only improved the efficiency of the electrochemical process, but also can increase the lipid content. The lipid extraction efficiency of the −5 V electric field increased from 17.7% and 28.5% to 20.4% and 31.1%, respectively, with one and two times extractions. The synergistic effect of the reverse diffusion of Cl− and electrochemical process was conducive for the improvement of the lipid extraction efficiency, and is expected to reduce the energy consumption of the lipid extraction process.

Zero-waste biorefinery of oleaginous microalgae as promising sources of biofuels and biochemicals through direct transesterification and acid hydrolysis

Oleaginous microalgae are considered as promising sources of biofuels and biochemicals due to their high lipid content and other high-value components such as pigments, carbohydrate and protein. This study aimed to develop an efficient biorefinery process for utilizing all of the components in oleaginous microalgae. Acetone extraction was used to recover microalgal pigments prior to processes for the other products. Microalgal lipids were converted into biodiesel (fatty acid methyl ester, FAME) through a conventional two-step process of lipid extraction followed by transesterification, and alternatively a one-step direct transesterification. The comparable FAME yields from both methods indicate the effectiveness of direct transesterification. The operating parameters for direct transesterification were optimized through response surface methodology (RSM). The maximum FAME yield of 256 g/kg-biomass was achieved when using chloroform:methanol as co-solvents for extracting and reacting reagents at 1.35:1 volumetric ratio, 70 °C reaction temperature, and 120 min reaction time. The carbohydrate content in lipid-free microalgal biomass residues (LMBRs) was subsequently acid hydrolyzed into sugars under optimized conditions from RSM. The maximum sugar yield obtained was 44.8 g/kg-LMBRs and the protein residues were recovered after hydrolysis. This biorefinery process may contribute greatly to zero-waste industrialization of microalgae based biofuels and biochemicals.

Effect of nutrient availability on lipid productivity of Botryococcus sp. (Botryococcaceae, Chlorophyta), a newly isolated tropical microalgae strain from Puerto Rico

Microalgae are promising sources of biofuels due to the high lipid content of some species. However, growing microalgae at large scales involves high production costs, mainly associated with nutrient inputs and harvesting processes. Therefore, to be cost competitive, species to be used as a source of fuels should be capable of accumulating lipids and biomass at lower fertilizer inputs. In the present study, we isolated and identified a native microalgal strain of Botryococcus sp. which was cultured under varying nitrogen, phosphorus and carbon dioxide regimes. The effects of nutrient availability on biomass, lipid production and fatty acid profiles were examined. We observed an increase in the relative lipid content from 25.5% under nitrogen non-limiting conditions to 41.8% under nitrogen deprivation. The lipid profile induced by nitrogen limitation was found to be dominated by saturated and monounsaturated lipid classes, meeting the European Standards for biodiesel and oil suitable for biofuel production. Thus, this Botryococcus sp. has the potential to be used at large scale cultures with the purpose of producing biofuels with lower fertilizer costs.

Relating nitrogen concentration and light intensity to the growth and lipid accumulation of Dunaliella viridis in a photobioreactor

The marine microalgal species Dunaliella viridis is a promising source of biofuels because of its ability to accumulate neutral lipids without freshwater resources for growth. Less energy for biofuel production from D. viridis may also be required because of the possible extraction of lipids through osmotic lysis. However, there is a lack of experimental data on the growth of D. viridis that can be used in mathematical models for process design. In this study, experiments were performed in a 3.2 L photobioreactor with both pH and temperature tightly controlled at 7.6 and 25 °C, respectively. Levels of neutral lipids, biomass, carbohydrate, chlorophyll, and cell counts of D. viridis were evaluated for ten days at various initial light intensities (100, 300, 400, and 600 μmol photons m−2 s−1) and nitrogen levels (9 and 60 g m−3 as nitrogen). The maximum lipid production observed was 26.9 g m−3 with 3.15 g m−3 day−1 average lipid productivity at an initial nitrogen concentration of 9 g m−3 and initial light intensity of 300 μmol photons m−2 s−1. The data show that D. viridis accumulates cellular carbohydrates as a primary carbon and energy storage product and then converts the cellular carbohydrates into cellular lipids as a secondary storage product when nitrogen is depleted. The on-line light data revealed linear relationships between real-time light intensity and biomass concentration (r = 0.96, p < 0.01) and between real-time light intensity and chlorophyll a concentration (r = − 0.89, p < 0.01), suggesting the possible use of real-time light data as a method for in situ quantification of biomass concentration and chlorophyll a concentration.

Emerging techniques for cell disruption and extraction of valuable bio-molecules of microalgae Nannochloropsis sp.

Microalgae of Nannochloropsis sp.present valuable source of bio-molecules (pigments, lipids, proteins) that have nutritional potential for the prevention and treatment of human diseases. Moreover, some species of Nannochloropsis are the promising sources of biofuels and excellent candidates for the replacement of classical biofuel crops. This review describes and compares the efficiency of different conventional and novel techniques that can be used for cell disruption and recovery of bio-molecules from Nannochloropsis sp. Classification of different extraction techniques includes chemical, enzymatic, mechanical and other physical methods. The detailed analysis of extraction efficiency assisted by pressure and temperature (subcritical and supercritical fluids, hydrothermal liquefaction), ultrasound, microwaves, and pulsed electric energy (pulsed electric fields and high voltage electrical discharges) is presented. The general discussion includes comparison between techniques, their effectiveness for cell disruption and selectivity of bio-molecules extraction from Nannochloropsis sp. The cost-effectiveness, benefits and limitations of different techniques are also analyzed.

Experimental processing of seaweeds for biofuels

The following paper provides an overview of the potential uses of seaweeds derived both from artificial cultivation as well as from eutrophic reservoirs as the feedstock for biofuels production. This review presents biochemical (anaerobic digestion [AD] and fermentation), chemical (extraction and transesterification) and thermochemical conversions (combustion, liquefaction, gasification and pyrolysis) of seaweeds for biofuels with special attention being paid to seaweeds processing such as pretreatment techniques, production methods and experimental conditions, and so forth. Seaweeds are considered as a suitable source for biogas and bioethanol production due to their high carbohydrate content. This review explores also the possibility of the application of oil extracted from seaweeds for biodiesel production. Since the chemical composition of seaweeds significantly differs from land biomass, a new comprehensive approach is required. Many macroalgal components are recalcitrant to bioconversion and pose microbiological challenges. The text deals with advantages and disadvantages of seaweeds as a feedstock for biofuels. Since macroalgae exploitation only for energy production is too expensive, seaweed integrated biorefineries were proposed as a solution which enables a development of high‐value algal bioproducts. Algae appear to be a promising source of biofuels. Utilization of waste algal biomass constitutes a link between the pollution abatement and energy production.This article is categorized under: Bioenergy &gt; Science and Materials

Simultaneous cell disruption and lipid extraction of wet aurantiochytrium sp. KRS101 using a high shear mixer.

Microalgae are regarded as a promising source of biofuels, and the concept of a microalgae-based biorefinery has attracted increasing attention in recent years. From an economic perspective, however, the process remains far from competitive with fossil fuels. This is particularly true of lipid extraction, due in part to the energy-intensive drying step. As a result, wet extraction methods have been studied as an economic alternative. In the present study, a novel extraction approach which utilizes high shear stress mixing was adopted and demonstrated for simultaneous lipid extraction and cell disruption to enable the retrieval of lipids directly from concentrated wet biomass. When a high shear mixer (HSM) was used to extract lipid from a dense biomass (> 350g/L) of the oleaginous algae Aurantiochytrium sp., it exhibited a yield of esterifiable lipids which exceeded 80% in 10min at 15,000rpm with various solvent types. The HSM was found to improve the lipid yields substantially with solvents less miscible with either lipids or water, such that the range of Hansen solubility parameters for the usable solvents became 3.3 times wider (14.9-26.5 MPa1/2). The HSM, which appeared effectively to loosen the water barrier that prevents solvent molecules from penetrating through the cell envelope, was found to be more efficient with hexane, hexane/isopropanol, and ethanol, all of which showed nearly identical lipid yields compared to the dry extraction process. The HSM can, indeed, offer a powerful mechanical means of lipid extraction with non-polar and less toxic solvents from wet biomass.

Effects of aeration intensity as agitation in simple photobioreactors on leptolyngbya (cyanobacteria) growth as biofuel feedstock

Indonesia known as a hotspot of biodiversity, including cyanobacteria biodiversity. One member of cyanobacteria (prokaryotic algae) is Leptolyngbya. Leptolyngbya HS-16 is an isolate that had been isolated from hot spring in Red Crater of Gunung Pancar, Sentul, Bogor. As mats-producing microalgae, this strain is a very promising source of Biofuel. Biofuel can be extracted from lipid of microalgal biomass. Bioreactor is a method to encourage the growth of microalgal biomass. To get a best result in growth, agitation must be done, to make sure every single cell of microalgae gets the adequate nutrition. The aeration on simple photobioreactors is set to high and low intensity. The high intensity of aerations average amount are 191 bubble/min, while the low intensity one are 117 bubble/min, with a device that could produce smaller bubble size to reduce the aeration-agitation effect. The research was done to acknowledge the effect of aeration intensity to Leptolygnbya HS-16.

Pretreatment optimization of the biomass of Microcystis aeruginosa for efficient bioethanol production

Microalgae are considered to be the future promising sources of biofuels and bio products. The algal carbohydrates can be fermented to bioethanol after pretreatment process. Efficient pretreatment of the biomass is one of the major requirements for commercialization of the algal based biofuels. In present study the microalga, M. aeruginsa was used for pretreatment optimization and bioethanol production. Treatment of algal biomass with CaO before acid and/or enzymatic hydrolysis enhanced the degradation of algal cells. Monomeric sugars yield was increased more than twice when biomass was pretreated with CaO. Similarly, an increase was noted in the amount of fermentable sugars when biomass was subjected to invertase saccharification after acid or lysozyme pretreatment. Highest yield of fermentable sugars (16 mM/ml) in the centrifuged algal juice was obtained. 4 Different microorganisms’ species were used individually and in combination for converting centrifuged algal juice to bioethanol. Comparatively higher yield of bioethanol (60 mM/ml) was obtained when the fermenter microorganisms were used in combination. The results demonstrated that M. arginase biomass can be efficiently pretreated to get higher yield of fermentable sugars for enhanced yield of bioethanol production.

Nitrogen starvation-induced accumulation of triacylglycerol in the green algae: evidence for a role for ROC40, a transcription factor involved in circadian rhythm.

Microalgal triacylglycerol (TAG), a promising source of biofuel, is induced upon nitrogen starvation (-N), but the proteins and genes involved in this process are poorly known. We performed isobaric tagging for relative and absolute quantification (iTRAQ)-based quantitative proteomics to identify Chlorella proteins with modulated expression under short-term -N. Out of 1736 soluble proteins and 2187 membrane-associated proteins identified, 288 and 56, respectively, were differentially expressed under -N. Gene expression analysis on select genes confirmed the same direction of mRNA modulation for most proteins. The MYB-related transcription factor ROC40 was the most induced protein, with a 9.6-fold increase upon -N. In a previously generated Chlamydomonas mutant, gravimetric measurements of crude total lipids revealed that roc40 was impaired in its ability to increase the accumulation of TAG upon -N, and this phenotype was complemented when wild-type Roc40 was expressed. Results from radiotracer experiments were consistent with the roc40 mutant being comparable to the wild type in recycling membrane lipids to TAG but being impaired in additional de novo synthesis of TAG during -N stress. In this study we provide evidence to support the hypothesis that transcription factor ROC40 has a role in -N-induced lipid accumulation, and uncover multiple previously unknown proteins modulated by short-term -N in green algae.

ALCOdb: Gene Coexpression Database for Microalgae.

In the era of energy and food shortage, microalgae have gained much attention as promising sources of biofuels and food ingredients. However, only a small fraction of microalgal genes have been functionally characterized. Here, we have developed the Algae Gene Coexpression database (ALCOdb; http://alcodb.jp), which provides gene coexpression information to survey gene modules for a function of interest. ALCOdb currently supports two model algae: the green alga Chlamydomonas reinhardtii and the red alga Cyanidioschyzon merolae. Users can retrieve coexpression information for genes of interest through three unique data pages: (i) Coexpressed Gene List; (ii) Gene Information; and (iii) Coexpressed Gene Network. In addition to the basal coexpression information, ALCOdb also provides several advanced functionalities such as an expression profile viewer and a differentially expressed gene search tool. Using these user interfaces, we demonstrated that our gene coexpression data have the potential to detect functionally related genes and are useful in extrapolating the biological roles of uncharacterized genes. ALCOdb will facilitate molecular and biochemical studies of microalgal biological phenomena, such as lipid metabolism and organelle development, and promote the evolutionary understanding of plant cellular systems.

Biofuel and Advanced Biofuel

A. Ethanol From Cellulose Cellulosic ethanol is the most promising second-generation biofuel, but the cost of production limits its viability, though costs are declining. (203) In order to qualify for a renewable identification number for cellulosic ethanol, production must meet requirements include lifecycle greenhouse gas emissions, as determined by the Administrator, that are at least 60 percent less than the baseline lifecycle greenhouse gas (GHG) emissions from gasoline or diesel, whichever the fuel is replacing. (204) In June 2012, the first tradable renewable identification number was issued to Blue Sugars for cellulosic ethanol production, but the company went bankrupt in 2013. (205) The CAA requires 0.1 billion gallons of cellulosic biofuel to be used in the year 2010 and its use to increase in steps to 16.0 billion gallons in 2022. (206) The administrator of EPA is given limited power in CAA section 211(o)(4) to modify the advanced biofuel and cellulosic requirements concerning the mandated percentages of GHG reductions. Section 211(o)(7)(A) allows the Administrator to modify the utilization requirements to prevent harm to the economy, the environment, or because of inadequate production. (207) This power has been used to adjust production requirements; in 2012, the industry produced only 20,069 gallons of fuel. (208) An alternative approach proposed by EPA to deal with the industry's performance is to change the definition of cellulosic ethanol to allow more fuels to qualify as cellulosic biofuels. (209) Technical amendments to the RFS to clarify the number of cellulosic biofuel identification numbers for fuels of varying cellulosic content were promulgated on July 8, 2014. (210) Ethanol produced from cellulose or other non-food inputs is a promising source of biofuels. It can be produced from trees and forest residues, although there is no commercial production of fuel from woody biomass except for the use of pulp and saw mill wastes to produce heat, steam, and electricity. (211) Fast growing woody crops such as hybrid willow and poplar have the potential to be feedstock for cellulosic fuel. (212) Another potential feedstock is perennial grass, such as switchgrass or Giant Miscanthus. Switchgrass is a perennial Midwest and Southeast grass with nearly three times the yield of hay. Giant Miscanthus is a native of Asia has some use as a fuel in Europe. The advantage of perennial grasses is they are not normally irrigated and therefore require less water, fertilizer, and pesticides than most crops, and their extensive root system reduces soil erosion and provides habitat for wildlife. (213) Some of the plants approved for renewable fuel production by EPA, such as giant reed and napier grass, are invasive species other government agencies are trying to control. (214) Agricultural residues not specifically grown for food such as corn stover can be used to produce cellulosic ethanol, although the use of corn stover for fuel could lead to increases in soil erosion. (215) A 2007 lifecycle study found the energy requirements for cellulosic fuel production are low for switchgrass and hybrid poplar feedstock when compared to corn crops. Other experts claim cellulosic ethanol has a 100 percent energy gain, compared to the 34 percent energy gain for corn. (216) Utilizing non-food inputs is important because if all of the United States corn harvest is devoted to ethanol production it would offset about 25 percent of national gasoline demand. (217) An advantage of using cellulosic feedstock is it can be grown on marginal or degraded land can provide increased regional agricultural income without utilizing land used for food production. (218) Moreover, cellulosic feedstocks require less pesticides and fertilizer than corn-based ethanol. (219) However, demand for cellulosic ethanol could result in adverse impacts on forests if they were cut to produce fuel or converted to plantations of fast growing trees. …