Potential Bioenergy Feedstock Research Articles

Effect of salt stress on the biomass productivity and potential bioenergy feedstock of Graesiella emersonii KNUA204 isolated from Ulleungdo Island, South Korea

Microalgae are versatile, profitable, and promising sources of bioenergy and high-value products, having various applications in the biotechnology industry. Herein, G. emersonii KNUA204 was isolated from Ulleungdo Island, South Korea, and exposed to stressors, i.e., MgCl2 (75 and 150 mM) and NaCl (200 and 400 mM), to investigate improvement in its biomass productivity and feasibility of the application of biomass. Treatment with mild MgCl2 (75 mM) afforded the highest specific growth rate (μ = 0.13 d−1), dry cell weight (3 g L−1), and total carbohydrate content (29.87%). Although all salt treatments decreased chlorophyll and carotenoid contents, treatment with high NaCl concentration (400 mM) afforded the highest zeaxanthin content (0.3 mg g−1). The proximate and ultimate analyses of biomass following treatment with 150 mM MgCl2 revealed 93.85% volatile matter and 22.55 MJ kg−1 calorific value, respectively, indicating that Graesiella emersonii KNUA204 can be potentially used as bioenergy feedstock. The biodiesel quality was established based on the fatty acid methyl ester profiles, and MgCl2 treatment increased the cetane number more than the control. Therefore, the treatment of G. emersonii KNUA204 with MgCl2 during cultivation could provide a microalgae-based bioenergy feedstock with high productivity.

The comprehensive characterization of Prosopis juliflora pods as a potential bioenergy feedstock

The production of renewable and sustainable biofuels using inevitable wastes is a promising alternative to the alarming depletion of fossil fuels. Significantly, the sustainable biorefinery of lignocellulosic waste, as an alternative fuel source, is a prognosticating approach to tackle many agricultural/forestry residues and offers a circular economy as well as environmental benefits. But, the heterogeneity of lignocellulosic biomass is one of the major bottlenecks in lignocellulosic biorefinery. Thus the characterization of lignocellulosic biomass is essential to understanding the feedstock's nature, composition and suitability for biofuel production. The present study taps evergreen spiny non-edible pods of Prosopis juliflora (Pj) as an energy feedstock. Proximate, ultimate and biochemical characterization of Pj pods were conducted, and thermal behaviour and calorific values were determined. Cellulose and hemicellulose were isolated and characterized by reliable methods. The overall characterization has revealed the Pj pods as a potential feedstock for bioenergy. The collected Pj pods contain (% w/w) moisture 7.89 ± 0.002, volatile matter 87.67 ± 0.002, ash 0.21 ± 0.002, fixed carbon 4.23 ± 0.002 with a calorific value of 17.62 kg/MJ. The CHNS content was (w/w %) carbon 41.77, nitrogen 3.58, sulfur 26.3 and hydrogen 6.55. The biochemical composition analysis yields (% w/w) on a dry basis; cellulose 26.6 ± 0.18, hemicellulose 30.86 ± 0.27, lignin 4.71 ± 0.12, protein 11.63 ± 0.12 and starch 1.1 ± 0.06 and extractives 30.56 ± 0.008. The isolated cellulose and hemicellulose were analyzed and confirmed by CP/MAS &1H NMR, FTIR, TG-DSC, SEM, XRD, and TGA. The present results revealed that the tested biomass, Prosopis juliflora, could be used as a feedstock in biorefinery for bioenergy.

Kinetics and thermodynamic study of Calligonum polygonoides pyrolysis using model-free methods

Pyrolysis kinetics was carried out for Calligonum polygonoides (C. Polygonoides) in an inert atmosphere at three different heating temperatures such as 10, 15, and 20 °C/min using thermogravimetric analysis. Physicochemical properties were studied using bomb calorimeter, elemental analyzer, and Fourier Transform Infrared Spectroscopy. C. Polygonoides have a calorific value of 16.33 MJ/kg. Gas chromatography–mass spectrometry was used to identify gases produced during pyrolysis. Thermogravimetric analysis was used to investigate the pyrolysis characteristics of biomass. Activation energy for the three zones of pyrolysis were determined using Kissinger and Ozawa model-free methods. Activation energy calculated for zone I, zone II and zone III using Ozawa and Kissinger model was 133.73, 164.50, 254 KJ/mol and 135.61, 165.88, and 253.00 KJ/mol, respectively. Thermodynamic parameters such as enthalpy, entropy, and Gibbs free energy were calculated for the three different zones. Kinetic and thermodynamic study confirmed that C. Polygonoides can be used as useful and potential bioenergy feedstock.

Engineering strategies and opportunities of next generation biofuel from microalgae: A perspective review on the potential bioenergy feedstock

The quest for alternate fuels that demonstrate reduced environmental impact is ever-increasing. This necessity has been a direct result of the environmental changes that are caused by the usage of fossil fuels. In this regard, sugar cane, corn and soybeans have been employed to make the first-generation biofuels. Second-generation biofuels, made from lignocellulosic crops and forest leftovers, require a lot of land that could have otherwise been utilized for food processing and productions. In this scenario, going by the technical forecasts, microalgae can potentially serve as the primary source for the third-generation of biofuels. By virtue of possessing no such limitations, microalgae are currently viewed as an effective alternative to first- and second-generation biofuels. The goal of this review is to highlight the most effective opportunities for biofuels production using algal sources. In doing so, this review also explains how the chemical compositions of micro and macroalgae, as well as the associated bioactive compounds, render positive influence on biofuel production. In addition to the present review critical discussions have been done on: (a) various growing strategies for rapid cultivation of micro and macroalgae for biomass development, (b) how algal-based ingredients and bioactive compounds are yet unexploited for bioenergy generation, and (c) why algal source and their biomass are regarded as possible bioenergy sources for future green and sustainable energy.

Multivariate Analysis of Seed Chemical Diversity among Jatropha curcas in Botswana

Jatropha (Jatropha curcas L.) has been identified as a potential bioenergy feedstock in arid regions, but knowledge of the diversity of its chemical characteristics is limited. In this study, 61 Jatropha accessions growing in Botswana, where both severe drought and winter frosts frequently occur, were analyzed for their seed chemical properties. Histogram analyses and meta-analysis comparisons with seeds from other countries/continents showed that the median/mean dry seed weight, toxic compound phorbol esters, and C18:0 fatty acid levels in the Botswanan accessions were lower than those from other countries/continents. A clustered heat map analysis indicated five clades for the Botswanan accessions, and their physicochemical traits were also categorized into five groups. Many positive and negative correlations were observed among the chemical traits, including negative correlations between the C18:3 (linolenic acid) content and yield-related traits (lipid content and dry seed weight). Principal component analysis highlighted the existence of accessions with highly deviated seed chemical compositions, such as those enriched in C18:0/C18:1 and C16:0/C16:1/C18:3 fatty acids. Overall, the present study suggests considerable diversity in the seed chemical compositions of Botswanan Jatropha accessions. Various accessions could be useful as feedstock for specific industrial products, as well as for breeding materials for the fortification of specific chemical ingredients.

Structural Characterization of Mixed Rice Straw and Deoiled Algal Cake-Based Substrate as a Potential Bioenergy Feedstock for Microbial Lipids and Carotenoid Production

Structural Characterization of Mixed Rice Straw and Deoiled Algal Cake-Based Substrate as a Potential Bioenergy Feedstock for Microbial Lipids and Carotenoid Production

Perceptions about switchgrass and land allocation decisions: Evidence from a farmer survey in Missouri

Switchgrass has been identified as a high potential bioenergy feedstock, and was expected to play an important role in achieving the production targets for cellulosic biofuels laid out under the Energy Security and Independence Act of 2007. However, the development of cellulosic biofuels at commercially viable levels has been slower than anticipated and supply side challenges, due to limited feedstock availability, continue to be a major bottleneck. Understanding the role of the farming community, their perceptions, and their willingness to cultivate dedicated bioenergy feedstocks is an important part of overcoming these challenges. To this end, a survey was administered in March-April 2017 and the results of our analysis are both insightful and timely. We studied the role of farmer perceptions around the suitability of switchgrass for their operations. We evaluated the impact of their perceptions and existing land uses on their willingness to cultivate switchgrass and their land allocation decisions using a 2-step Heckman model. Factors such as potential for diversification of crop-mix, creation of habitat for wildlife, as well as ownership of woodland or forestland played an important role in influencing farmer willingness to cultivate switchgrass. We also found that land allocated for switchgrass cultivation was more likely to come from lands under non-crop uses, such as hay or other land use, and was unlikely to cause displacement of lands used for cultivating row crops, which obviates conflicts that could arise from competing land use vis-à-vis food-crops.

Chemical composition and calorific value of elephant grass varieties and other feedstocks intended for direct combustion

AbstractPerennial grasses display several positive attributes as suitable energy crops for use as a solid fuel for direct combustion, such as high annual production of dry matter per unit area, perennity and high harvest flexibility. This study aimed to characterize the chemical composition and calorific value of 18 elephant grass (EG) varieties (Pennisetum purpureum Schum.) and 10 other potential bioenergy feedstocks intended for direct combustion. Samples were obtained from 6‐month‐old EG and sorghum and 3‐year‐old eucalyptus, Mimosa caesalpiniaefolia, and bamboo plants. Sugarcane bagasse and straw, rice husk, corn stover, coconut husk, and fiber samples were also evaluated. The elemental composition, lower heating value (LHV), and cellulose (CEL), hemicellulose (HCEL), lignin (LIG) and ash contents (% dry matter) were analyzed. The results indicated that the EG genotypes showed significant differences when compared with other evaluated biomasses, but showed no differences among themselves. The EG varieties showed a mean LHV (16.7 MJ/kg) superior to that of rice husk, sugarcane bagasse, and sorghum and similar to that of sugarcane straw, coconut fiber, and corn stover. The EG varieties showed a mean ash content (4.74%) inferior to that of rice husk, sugarcane bagasse, coconut fiber, and sorghum; a mean CEL content (36.0%) similar to that of sugarcane straw, coconut fiber, corn stover, sorghum, and Mimosa caesalpinifolia; HCEL; a mean HCEL content (30.3%) superior to that of rice husk, bamboo, eucalyptus, M. caesalpinifolia, coconut husk, and fiber; and a mean LIG content (8.80%) superior to that of corn stover and similar to that of sorghum, sugarcane bagasse, and straw biomass. The significant capacity of EG to accumulate dry matter was associated with the biomass quality attributes (LHV and CEL, HCEL, LIG, and ash contents), thereby making it an excellent alternative to lignocellulosic feedstock for direct combustion.

Birds and Bioenergy within the Americas: A Cross-National, Social–Ecological Study of Ecosystem Service Tradeoffs

Although renewable energy holds great promise in mitigating climate change, there are socioeconomic and ecological tradeoffs related to each form of renewable energy. Forest-related bioenergy is especially controversial, because tree plantations often replace land that could be used to grow food crops and can have negative impacts on biodiversity. In this study, we examined public perceptions and ecosystem service tradeoffs between the provisioning services associated with cover types associated with bioenergy crop (feedstock) production and forest habitat-related supporting services for birds, which themselves provide cultural and regulating services. We combined a social survey-based assessment of local values and perceptions with measures of bioenergy feedstock production impacts on bird habitat in four countries: Argentina, Brazil, Mexico, and the USA. Respondents in all countries rated birds as important or very important (83–99% of respondents) and showed lower enthusiasm for, but still supported, the expansion of bioenergy feedstocks (48–60% of respondents). Bioenergy feedstock cover types in Brazil and Argentina had the greatest negative impact on birds but had a positive impact on birds in the USA. In Brazil and Mexico, public perceptions aligned fairly well with the realities of the impacts of potential bioenergy feedstocks on bird communities. However, in Argentina and the USA, perceptions of bioenergy impacts on birds did not match well with the data. Understanding people’s values and perceptions can help inform better policy and management decisions regarding land use changes.

The impacts of bioenergy pine plantation management practices on bee communities

AbstractCultivation of bioenergy feedstocks is a growing land‐use world‐wide, yet we have a poor understanding of how bioenergy crop management practices affect biodiversity. This knowledge gap is particularly acute for candidate cellulosic bioenergy feedstocks, such as tree plantations, and for organisms that provide important ecosystem services, such as pollinators.We examined bee communities in 83 sites across three states in the southeastern United States—Alabama, Florida and Georgia. We compared bee abundance and diversity in 66 pine plantation sites that reflect management with and without potential bioenergy feedstock production. At least three bioenergy feedstock production methods have been proposed for this region: (a) converting conventional timber stands to short‐rotation bioenergy plantations; (b) harvesting feedstock by thinning conventional plantations; and (c) harvesting of woody debris residues after plantations have been clear‐cut.We found that bioenergy‐associated management practices including younger plantations (relative to older) and woody debris removal (relative to debris unremoved) in clear‐cut plantations were associated with reduced bee diversity. Removing ground debris in clear‐cut plantations also drastically increased bee abundance, though this effect was largely driven by strong dominance of just two bee species. Clear‐cut plantations had lower beta diversity than standing plantations.Synthesis and applications. Management practices associated with bioenergy feedstock production can have negative effects on bee community diversity. In particular, harvesting of debris in clear‐cut plantations dramatically reduces bee diversity. Large‐scale bioenergy feedstock production that increases the prevalence of young and clear‐cut stands may cause landscape‐level beta diversity to decline. Nevertheless, bioenergy pine plantations likely support higher bee diversity than corn fields, an alternative bioenergy feedstock.

Allometric Relationships for Predicting Aboveground Biomass and Sapwood Area of Oneseed Juniper (Juniperus monosperma) Trees.

Across the semiarid ecosystems of the southwestern USA, there has been widespread encroachment of woody shrubs and trees including Juniperus species into former grasslands. Quantifying vegetation biomass in such ecosystems is important because semiarid ecosystems are thought to play an important role in the global land carbon (C) sink, and changes in plant biomass also have implications for primary consumers and potential bioenergy feedstock. Oneseed juniper (Juniperus monosperma) is common in desert grasslands and pinyon–juniper rangelands across the intermountain region of southwestern North America; however, there is limited information about the aboveground biomass (AGB) and sapwood area (SWA) for this species, causing uncertainties in estimates of C stock and transpiration fluxes. In this study, we report on canopy area (CA), stem diameter, maximum height, and biomass measurements from J. monosperma trees sampled from central New Mexico. Dry biomass ranged between 0.4 kg and 625 kg, and cross-sectional SWA was measured on n = 200 stems using image analysis. We found a strong linear relationship between CA and AGB (r2 = 0.96), with a similar slope to that observed in other juniper species, suggesting that this readily measured attribute is well suited for upscaling studies. There was a 9% bias between different approaches to measuring CA, indicating care should be taken to account for these differences to avoid systematic biases. We found equivalent stem diameter (ESD) was a strong predictor of biomass, but that existing allometric models underpredicted biomass in larger trees. We found SWA could be predicted from individual stem diameter with a power relationship, and that tree-level SWA should be estimated by summing the SWA predictions from individual stems rather than ESD. Our improved allometric models for J. monosperma support more accurate and robust measurements of C storage and transpiration fluxes in Juniperus-dominated ecosystems.

Characterization of the woody biomass feedstock potential resulting from California\u2019s drought

Regional tree die-off events generate large quantities of standing dead wood, raising concern over catastrophic wildfire and other hazards. Governmental responses to tree die-off have often focused on incentivizing biomass energy production that utilizes standing dead trees removed for safety concerns. However, the full distribution of potential woody bioenergy feedstock after tree die-off has not been evaluated due to the complexities of surveying and precisely measuring large forested areas. In this paper, we present a novel method for estimating standing dead biomass at a fine spatial resolution that combines aerial survey data with forest structure maps. Using this method, we quantify biomass generated by the unprecedented tree die-off that occurred in California following a 4-year drought and widespread pest outbreaks. The results are used to estimate feasibly recoverable feedstock for energy production. We find that approximately 95.1 million bone-dry tons (BDT) of dead biomass resulted from 2012–2017 mortality, with a lower bound of 26.2 million BDT. In other words, of the aboveground live tree biomass in 2012, ~1.3–4.8% died by 2017. Of the standing dead biomass, 29% meets minimum constraints for potential cost-effective bioenergy feedstock. This proportion drops to as low as 15% in the most affected areas due to terrain slope, wilderness status, and other factors, highlighting the need to complement disposal via biomass energy with other strategies to mitigate the risks of the tree mortality crisis, which is likely to only become more severe over time due to climate change.

Residues and bio-energy generation: A case study modelling value chain optimisation in Tasmania

Internationally biomass residues, primarily from forestry and agricultural production cycles, are increasingly being used to produce bio-energy. This case study presents modelling of the potential socio-economic impacts from a proposed co-generation bio-energy plant (under 50 MW) in the Valley Central Industrial Precinct (VCIP) in Northern Tasmania. The modelling uses data related to residue availability and bio-energy generation output to examine and evaluate potential impacts under a range of scenarios. Potential bio-energy residue feedstock is categorised into viable onsite and offsite sources and quantified in terms of their different bio-energy outputs for different sized bio-energy plants. To complete the evaluation of the potential socio-economic impact of the proposed plant, analysis is conducted using the JEDI (Jobs and Economic Development Impact model). The results of the modelling indicate that the location, quality and quantity of biomass residue feedstock and optimal socio-economic impacts are best aligned with the local supply chain by a bio-energy plant of (10 MW). Importantly, the modelling presented in this paper excludes consideration of forest harvest residues as a potential source of biomass residues due to the lack of certainty on the viability of commercial supply to the VCIP. In this context, it is anticipated that the underlying assumptions and approach used in this case study will be of value to other regions exploring the viability of bioenergy generation from biomass residues.

Impacts of nitrogen fertilization rate and landscape position on select soil properties in switchgrass field at four sites in the USA

Switchgrass (Panicum virgatum L.) has been recognized as a potential bioenergy feedstock due to its high yield potential and benefits to the environment. However, little is known about the impacts of nitrogen fertilization and landscape position on soil properties in switchgrass fields at multiple locations in the USA. The objective of this study was to assess the impacts of application of nitrogen fertilization rate (N rate; zero, 0; medium, 56; and high, 112 kg ha−1) and landscape position (shoulder, backslope, and footslope) on soil pH, electrical conductivity (EC), soil organic carbon (SOC), total nitrogen (TN), nitrate-N (NO3−-N), and ammonium-N (NH4+-N). This experiment was established in 2008 at four sites in Oklahoma (OK), South Dakota (SD), New York (NY), and Virginia (VA). Data showed that the N rate significantly increased NO3−-N for the 0–5 and 5–15 cm depths at the SD, NY, and VA sites. Compared with the zero N rate, the high N rate averagely increased NO3−-N by 75.7% for the two depths and three sites. The SOC and TN increased with the increase in N rate at most of the depths. The landscape position significantly reduced soil pH and increased EC, SOC, TN, NO3−-N, and NH4+-N at the footslope compared with the shoulder and backslope positions in most depths at the SD site (no position data at the NY and VA sites). The pH generally increased and the SOC, TN, and NO3−-N reduced with the increase in soil depth. These findings indicate that switchgrass production has the potential to improve or maintain soils in the USA.

Impacts of Nitrogen Rate and Landscape Position on Soils and Switchgrass Root Growth Parameters

Core Ideas Nitrogen rate did not affect soil properties for Oklahoma, South Dakota, and Virginia. Landscape position affected soil properties under higher slope. Nitrogen rate affected root N, surface area, and weight for the total profile. Landscape position affected the root C and N. Switchgrass roots can increase C accumulation and reduce risk of N loss in soils. ABSTRACTSwitchgrass (Panicum virgatum L.) has been recognized as a potential bioenergy feedstock, and can positively impact soils and the environment. The experimental sites were established in 2008 at three locations with each in Oklahoma (OK), South Dakota (SD), and Virginia (VA) to assess the impacts of N fertilization rate (N rate; low, 0 kg ha−1; high, 112 kg ha−1) and landscape position (shoulder, backslope, and footslope) on select soil properties and root growth parameters. Data indicate that N rate did not affect soil bulk density (BD), pH, electrical conductivity (EC), soil organic carbon (SOC), and total nitrogen (TN) for any of five depths. Landscape position impacted some of these properties by depth, depending on location. The N rate influenced root weight (RW), root surface area (RSA), and root total nitrogen (RTN) for the total profile (0–100‐cm depth) depending on local site conditions. The landscape position impacted RW, root total carbon (RTC), and RTN for total profile according to different site conditions. The interactions of landscape position by N rate on switchgrass root parameters were significant. The findings in this study indicate that the root system of switchgrass could improve soils and increase C accumulation and reduce the risk of N loss to benefit the environment.

Long‐term Biomass and Potential Ethanol Yields of Annual and Perennial Biofuel Crops

Core Ideas Annual crops produced a third more biomass and three times as much ethanol as perennials. Perennial crops used half as much nitrogen fertilizer as annual crops. Grain from most annual crops enhanced ethanol production per unit of biomass. Sweet sorghum produced substantially more ethanol than all other crops. Sorghum yielded more biomass and potential ethanol than corn in hot, dry years. Although energy crops could eventually supply a growing portion of cellulosic biofuel feedstocks, long‐term comparisons of annual and perennial crops are rare. An experiment was established in 2007 near Manhattan, KS, to compare biomass productivity and ethanol yield of perennial and annual crops. Perennial crops included three C4 grasses: switchgrass (Panicum virgatum L.), big bluestem (Andropogon gerardii Vitman), and miscanthus (Miscanthus sacchariflorus). Annual C4 crops were corn (Zea mays L.) in two rotations: continuous and rotated with soybean [Glycine max (L.) Merr.]; and five types of sorghum [Sorghum bicolor (L.) Moench]: photoperiod sensitive, sweet, dual purpose (grain and biomass), brown mid‐rib, and grain; all rotated with soybean. Annual crops produced 7 Mg ha−1 yr−1 more biomass than perennial crops throughout 11 yr, with sweet sorghum exceeding 22 Mg ha−1 yr−1, and 12 m3 ha−1 yr−1 of ethanol. Biomass yield of miscanthus approached 14 Mg ha−1 yr−1, essentially the same as for several annual crops but with half as much fertilizer nitrogen. Annual ethanol production from miscanthus and switchgrass was 3.6 m3 ha−1 yr−1, half as much as that of several annual crops that produced similar biomass yields. Big bluestem consistently produced the least biomass and ethanol, less than 7 Mg ha−1 yr−1 and 1.7 m3 ha−1 yr−1, respectively. Rotated corn averaged 7.1 m3 ha−1 yr−1 of ethanol. Eleven years of results indicate that annual corn and sorghum crops as well as perennial grasses such as miscanthus and switchgrass could play a role as potential bioenergy feedstocks in diversified production systems.

Sustainable bio-energy potential of perennial energy grass from reclaimed coalmine spoil (marginal sites) of India

Usage of marginal lands to grow perennial grass for biomass feedstocks is a promising option to meet the bioenergy demand in India. In this context, the present work investigated the potential utility of two perennial grass species Cenchnis ciliaris (L) and Pennisetum pedicellatum (Tan.) to be a new promising energy source for bioenergy. This study entails a detailed characterization of biomass feedstocks using proximate and ultimate analysis, and lignocellulosic fractions and thermogravimetric behaviour using TG-FTIR and Py-GCIMS spectrophotometry to evaluate their potential as an alternate green fuel to fossil fuels by measuring their thermochemical conversion functioning. Property analysis of perennial grass species showed a significant difference in moisture content (7.2-8.5%), volatile matters (80.5-82.4%), fixed carbon (11.3-18.9%), HHV (15-17.8 Mj/kg) and LHV (14.3-16.5 Mj/kg), which is very promising for bioenergy generation. Lignocellulosic fractions of biomass feedstocks are comparable to the previous studied biomass species including switchgrass and elephant grass. The individual decomposition experiments indicated that biomass feedstocks possess higher thermochemical reactivity and shorter devolatilization time. According to Py-GC/MS study, carbonyl compounds including aldehyde and ketones are the major volatile products, in addition to furans, benzenes, phenols, acids, and others. The TGR1R results showed that main gaseous products evolved during devolatilization are CO, CO2, CH4, and H2O. All of the results and findings would help in characterizing the biomass as potential bioenergy feedstocks compatible with other biomass currently in use as supplementary fuel for power generation. (C) 2018 Elsevier Ltd. All rights reserved.

Abiotic Stresses Modulate Landscape of Poplar Transcriptome via Alternative Splicing, Differential Intron Retention, and Isoform Ratio Switching.

Abiotic stresses affect plant physiology, development, growth, and alter pre-mRNA splicing. Western poplar is a model woody tree and a potential bioenergy feedstock. To investigate the extent of stress-regulated alternative splicing (AS), we conducted an in-depth survey of leaf, root, and stem xylem transcriptomes under drought, salt, or temperature stress. Analysis of approximately one billion of genome-aligned RNA-Seq reads from tissue- or stress-specific libraries revealed over fifteen millions of novel splice junctions. Transcript models supported by both RNA-Seq and single molecule isoform sequencing (Iso-Seq) data revealed a broad array of novel stress- and/or tissue-specific isoforms. Analysis of Iso-Seq data also resulted in the discovery of 15,087 novel transcribed regions of which 164 show AS. Our findings demonstrate that abiotic stresses profoundly perturb transcript isoform profiles and trigger widespread intron retention (IR) events. Stress treatments often increased or decreased retention of specific introns – a phenomenon described here as differential intron retention (DIR). Many differentially retained introns were regulated in a stress- and/or tissue-specific manner. A subset of transcripts harboring super stress-responsive DIR events showed persisting fluctuations in the degree of IR across all treatments and tissue types. To investigate coordinated dynamics of intron-containing transcripts in the study we quantified absolute copy number of isoforms of two conserved transcription factors (TFs) using Droplet Digital PCR. This case study suggests that stress treatments can be associated with coordinated switches in relative ratios between fully spliced and intron-retaining isoforms and may play a role in adjusting transcriptome to abiotic stresses.

Integrated Haematococcus pluvialis biomass production and nutrient removal using bioethanol plant waste effluent

Abstract The integrated system of astaxanthin and microalgal biomass production, and wastewater treatment is a promising process. Haematococcus pluvialis is a suitable microalgae for this coupled system to achieve this dual purpose in a single approach. In this study, biomass production and nutrient removal from bioethanol plant wastewater by H. pluvialis were investigated. An air-lift photobioreactor was used to utilize the wastewater as well as a CO2-enriched gas supply. The maximum biomass density and maximum specific growth rate achieved were 4.37 ± 0.007 g/L and 0.317 day−1, respectively, by culturing H. pluvialis in an air-lift photobioreactor, supplemented with 5% CO2 in air. Removal of 91.7% total nitrogen and 100% total phosphorous from the wastewater was achieved. The residual microalgal biomass, obtained after astaxanthin extraction (1.109 ± 0.009 mg/g DW), was characterized as a potential bioenergy feedstock due to its elevated higher heating value 15.6 ± 0.01 MJ/kg. Hence, integrating H. pluvialis cultivation with bioethanol effluent serves the combined purpose of wastewater treatment, CO2 utilization, and simultaneous production of astaxanthin, which has a potential market value of over USD 2000 per kg, and carbohydrate rich microalgal biomass, which can be applied to bioenergy production.

A Computational Tool for Comparative Energy Cost Analysis of Multiple-Crop Production Systems

Various crops can be considered as potential bioenergy and biofuel production feedstocks. The selection of the crops to be cultivated for that purpose is based on several factors. For an objective comparison between different crops, a common framework is required to assess their economic or energetic performance. In this paper, a computational tool for the energy cost evaluation of multiple-crop production systems is presented. All the in-field and transport operations are considered, providing a detailed analysis of the energy requirements of the components that contribute to the overall energy consumption. A demonstration scenario is also described. The scenario is based on three selected energy crops, namely Miscanthus, Arundo donax and Switchgrass. The tool can be used as a decision support system for the evaluation of different agronomical practices (such as fertilization and agrochemicals application), machinery systems, and management practices that can be applied in each one of the individual crops within the production system.