Sugarcane Feedstock Research Articles

Techno-economics and environmental assessment of sorbitol and itaconic acid production from sugarcane-based feedstock

Production of sorbitol or itaconic acid from sugarcane feedstocks in energy self-sufficient biorefinery scenarios were investigated, via Aspen Plus® simulations, techno-economic and environmental assessments. Sorbitol co-produced with fructose from A-molasses had a minimum selling price (MSP) (0.81 $/kg) similar to technical-grade sorbitol market prices (0.5 to 1.1$/kg), and an internal rate of return (IRR) of 19.65%. Sorbitol co-produced with mannitol from A-molasses had a lower MSP (0.48 $/kg), below food-grade sorbitol prices (0.58$/kg) and a higher IRR (23.63%). Combining A-molasses with lignocelluloses for the co-production of sorbitol and mannitol increased the MSP (0.63 $/kg) above the market price and decreased the IRR (18.46%). This scenario also had greenhouse gas emissions lower than that of its A-molasses only counterpart, mainly due to the method of hydrogen production. Itaconic acid production from sugarcane feedstocks in similar scenarios was unattractive due to lower IRRs (4.49% to 11.61%).

Integrated sensing and machine learning: Predicting saccharine and bioenergy feedstocks in sugarcane

Predicting saccharine and bioenergy feedstocks in sugarcane enables growers and industries to determine the precise time and location for harvesting a better-quality product in the field. On one hand, Brix, Purity, and total recoverable sugars (TRS) can provide meaningful and reliable indicators of high-quality raw materials for first-generation (1 G) bioethanol. Conversely, Cellulose, Hemicellulose, and Lignin are the primary constituents of straw, directly contributing to second-generation (2G) bioethanol. However, analyzing these materials in the laboratory is a time-consuming and non-scalable task. Therefore, we propose an approach based on a multi-sensor framework, which includes multispectral unmanned aerial vehicle (UAV) imagery, thermal, photosynthetic active radiation (PAR), and chlorophyll fluorescence (ChlF) data, along with machine learning (ML) algorithms namely random forest (RF), multiple linear regression (MLR), decision tree (DT), and support vector machine (SVM), to develop a non-invasive and predictive framework for mapping sugarcane feedstocks. We collected samples of stalks and leaves/straw during the maturity stage while simultaneously collecting remote sensing data. The ML models played a crucial role in predicting 1 G (R2 = 0.88–0.93) and 2 G (R2 = 0.56–0.82) feedstocks. Notably, remote sensing data could serve as important features for the models, mainly through the spectral bands (Blue, Green, and RedEdge), DTemp and ChlF. Hence, the best features can be further implemented within a framework to predict sugarcane feedstocks. Our study marks a significant advancement in the industrial-scale prediction of sugarcane feedstocks, providing stakeholders with invaluable prescriptive harvesting strategies for both primary products and by-products.

Comparative techno-economics of 1,3-butadiene production from sugarcane feedstocks via ethanol or 2,3-butanediol as intermediates

The global sugar industry has stagnated due to oversupply of the markets with conventional sugar products. Shifting from sugar-only production to co-production of other valuable products, through the integration of biorefineries into existing sugar mills, may open new revenue streams and investment opportunities. The economic feasibilities of various biorefinery scenarios for the production of 1,3-butadiene, by annexation to an existing sugar mill, were investigated. Pathways using either 2,3-butanediol or ethanol as intermediate product were compared, using A-molasses (first-generation), and sugarcane bagasse and brown leaves (second-generation) as feedstocks. The processes were simulated from literature data using Aspen Plus® software for subsequent techno-economic and sensitivity analyses. Producing 1,3-butadiene via the 2,3-butanediol pathway proved to have more attractive economics, with minimum selling prices of 4.08 $/kg and 4.55 $/kg for first-generation-only and integrated/combined first- and second-generation feedstocks, respectively, compared to the ethanol pathway at 5.71 $/kg and 5.72 $/kg. This was mainly attributed to low catalytic performance and higher capital costs associated with the ethanol-to-butadiene catalytic conversion. The investigated scenarios were unprofitable compared to a market price of 1.05 $/kg for fossil-derived 1,3-butadiene, requiring substantial price premiums for bio-based 1,3-butadiene. Instead, the sole production of bio-based 2,3-butanediol as final biorefinery product was deemed to be more viable for investment.

Yeast population dynamics in Brazilian bioethanol production.

The large-scale and nonaseptic fermentation of sugarcane feedstocks into fuel ethanol in biorefineries represents a unique ecological niche, in which the yeast Saccharomyces cerevisiae is the predominant organism. Several factors, such as sugarcane variety, process design, and operating and weather conditions, make each of the ∼400 industrial units currently operating in Brazil a unique ecosystem. Here, we track yeast population dynamics in 2 different biorefineries through 2 production seasons (April to November of 2018 and 2019), using a novel statistical framework on a combination of metagenomic and clonal sequencing data. We find that variation from season to season in 1 biorefinery is small compared to the differences between the 2 units. In 1 biorefinery, all lineages present during the entire production period derive from 1 of the starter strains, while in the other, invading lineages took over the population and displaced the starter strain. However, despite the presence of invading lineages and the nonaseptic nature of the process, all yeast clones we isolated are phylogenetically related to other previously sequenced bioethanol yeast strains, indicating a common origin from this industrial niche. Despite the substantial changes observed in yeast populations through time in each biorefinery, key process indicators remained quite stable through both production seasons, suggesting that the process is robust to the details of these population dynamics.

Water-energy-food nexus of local bioeconomy hub and future climate change impact implication

Policies on bioeconomy are some of the key emerging ones around the world to support sustainability in terms of using renewable resources. However, these may lead to significant demand for biomass feedstock which relies on limited resources, viz., water, land, and energy. The impact of climate change on water availability makes it more challenging. This paper demonstrates the analysis of the water, energy, and food resource nexus of a bioeconomy-based industrial complex and future climate change impact. The model structure consists of cultivation, crop processing, and urban sectors. Sugarcane is the major crop in the case study area and is the main bioeconomy crop.The results indicate that the average sugarcane yield will be lower than the minimum industrial goal for the 2020s and 2030s decades. Consequently, sugarcane feedstock shortage may often occur. The drought situation tends to be increased, so groundwater resources can be the main reserve source of water. In all improvement scenarios on water supply management, nexus energy used for water acquisition was mainly for groundwater acquisition. Direct energy use in the cultivation process is high and fossil fuels based, while most of the energy used in processing came from biomass waste. This implies that technologies for water acquisition will be more important in the future and should be developed in terms of energy efficiency and the aspect of promoting the usage of renewable energy to reduce greenhouse gases and fossil fuels use. The impact of climate change will cause significant fluctuations in the annual rainfall characteristics of the study area. An additional irrigation water supply of about 250 mm and expansion to cover more than 90% of the cultivation area should be considered to secure the minimum supply of sugarcane for the local biorefinery complex in the following decades.

Facile Synthesis of Metal-Impregnated Sugarcane-Derived Catalytic Biochar for Ozone Removal at Ambient Temperature

This study presents the first attempt at employing catalytic biochar to remove ground-level ozone at ambient temperature. With the increase in human activity, ozone has become a critical inorganic pollutant that needs to be addressed, using more sustainable methods. Fe- and Mn-impregnated catalytic biochars were prepared from a sugarcane feedstock via the wet impregnation method and pyrolysis at various temperatures, where the optimum value was determined to be 550 °C. The metal-impregnated biochar samples demonstrated enhanced surface areas and pore volumes compared with the pristine biochar (SCB550), resulting in improved ozone-adsorption capacity. SCB550-Fe exhibited an ozone-adsorption capacity of 52.1 mg/g at 20 ppm, which was approximately four times higher than that of SCB550. SCB550-Fe demonstrated superior ozone-removal performance compared to SCB550-Mn; 122 mg/g capacity as opposed to 116.2 mg/g at 80 ppm, respectively. Isothermal and kinetic modeling are also presented to suggest a plausible mechanism of ozone removal by catalytic biochar. This includes physical adsorption, complexation, electrostatic interaction, and electron transfer during the redox reaction between ozone and metals. Overall, this study should provide preliminary insights into ozone removal using biochar and promote further research regarding material optimization and kinetic studies.

Biohythane: a Potential Biofuel of the Future.

Today, the world is becoming more dependent on fossil fuels. The major drawbacks of these non-renewable energy resources include an extreme environmental pollution and an extinction threat. Several technologies including microalgal biodiesel production, biomass gasification, and bioethanol production have been explored for the generation of renewable energy especially, biofuels. One such promising research has been carried out in the generation of biohythane which has the potential to become an alternative fuel to the existing non-renewable ones. It has been reported that biohydrogen can be produced from organic wastes or agricultural feedstocks with the help of acidogens. Dark fermentation can be carried out by acidogens to produce biohydrogen under anaerobic conditions by utilizing lignocellulosic biomass or sugarcane feedstocks in the absence of light. The spent medium contains volatile short-chain fatty acids like acetate, butyrate, and propionate that can serve as substrates for acetogenesis followed by methane biosynthesis by methanogens. Therefore, the sequential two-stage anaerobic digestion (AD) involves a production of biohydrogen followed by the biosynthesis of methane. This combined process is termed as a single eponym "Biohythane" (hydrogen + methane). Several studies have demonstrated about the effectiveness of biofuel, and it is believed to have a greater energy recovery, environmental friendliness, and shorter fermentation time. Biohythane can serve as an alternative future green biofuel and solve the present energy crisis in India as well as the entire world.

Comparative assessment of the co-production of bioethanol and single cell proteins from Sugarcane Bagasse, Rice Husks, and cassava peels using Saccharomyces cerevisiae

This work compares various waste sources of feedstock (cassava peels, sugarcane bagasse, and rice husks) for the co-production of bioethanol and single cell protein using Saccharomyces Cerevisiae as fermentation enzyme. Sulphuric acid solution was used for the pre-treatment, dilute hydrochloric acid was used for hydrolysis, temperature, time, and pH of 131.8 °C, 1 hr, and 5.3 respectively. Sodium hydroxide (NaOH) was used to adjust the pH of the hydrolysate to neutral (6.7). The primary component of the single-cell protein was ammonia (NH3), which was quantified using Kjeldahl's technique of analysis, while the bioethanol produced was assessed using the colorimetric and colored reaction method using a spectrophotometer. Sugarcane bagasse showed the highest amount of bioethanol (36.57 %) while Rice husks and Cassava peels showed 30.97 % and 29.31 % respectively. The greatest bioethanol production (47.85 %) was achieved by combining feedstock, cassava, and sugar cane feedstocks. The percentage of single cell protein generated from individual feedstock was the highest using sugarcane bagasse (29.4 %) while a sugarcane bagasse and cassava peels combination gave the highest concentration for single cell protein (43.6 %). The study has demonstrated efficient bioethanol and single cell protein (SCP) co-production from Saccharomyces Cerevisiae using sugarcane bagasse, cassava peels, and rice husk as feedstock.

Saccharification of agricultural lignocellulosic feedstocks by endogenous and symbiotic cellulases from the subterranean termites

This study investigated the protein fraction-level in vitro and in vivo saccharification potential by the guts of two geographically different lower termites’ species Reticulitermes flavipes and Heterotermes indicola using biofuel producing feedstocks sugarcane bagasse, pinewood, cottonwood, corn stover, and rice husk. The gut protein extract from both termite species saccharified all lignocellulose material regardless of feedstock loading. However, R. flavipes showed significantly (p < 0.05) higher saccharification potential than H. indicola. Consumption of the sugarcane bagasse, pinewood, and corn stover was maximum by R. flavipes, whereas H. indicola exposed cottonwood and sugarcane feedstocks as the most palatable food source with 100% survivability. This study also hypothesized that feeding on various feedstocks will show variable impacts on enzyme activities. An adaptive mechanism enables the termites and their endosymbionts for optimized consumption of variable food sources. Results supported "diet adaptation" hypothesis by indicating β-glucosidase, exoglucanase, and xylanase activities, which were significantly the highest for sugarcane bagasse, pinewood, and cottonwood to rice husk and control diets in both termite species. These results are important in physiological changes in termites that lead to gut microbial environment changes and 100% survivability on exclusive sugarcane bagasse, pinewood, and cottonwood feedstocks. Both termite species' guts exhibit the clear saccharification for all feedstocks, which validate the H indicola and R. flavipes systems as a potential source for lignocellulose biomass digesting enzymes particularly β-glucosidase, endoglucanase, exoglucanase, and xylanases.

Near-infrared spectroscopy outperforms genomics for predicting sugarcane feedstock quality traits.

The main objectives of this study were to evaluate the prediction performance of genomic and near-infrared spectroscopy (NIR) data and whether the integration of genomic and NIR predictor variables can increase the prediction accuracy of two feedstock quality traits (fiber and sucrose content) in a sugarcane population (Saccharum spp.). The following three modeling strategies were compared: M1 (genome-based prediction), M2 (NIR-based prediction), and M3 (integration of genomics and NIR wavenumbers). Data were collected from a commercial population comprised of three hundred and eighty-five individuals, genotyped for single nucleotide polymorphisms and screened using NIR spectroscopy. We compared partial least squares (PLS) and BayesB regression methods to estimate marker and wavenumber effects. In order to assess model performance, we employed random sub-sampling cross-validation to calculate the mean Pearson correlation coefficient between observed and predicted values. Our results showed that models fitted using BayesB were more predictive than PLS models. We found that NIR (M2) provided the highest prediction accuracy, whereas genomics (M1) presented the lowest predictive ability, regardless of the measured traits and regression methods used. The integration of predictors derived from NIR spectroscopy and genomics into a single model (M3) did not significantly improve the prediction accuracy for the two traits evaluated. These findings suggest that NIR-based prediction can be an effective strategy for predicting the genetic merit of sugarcane clones.

Polyhydroxyalkanoate Synthesis by Burkholderia glumae into a Sustainable Sugarcane Biorefinery Concept

Polyhydroxyalkanoate (PHA) bioplastic was synthesized by Burkholderia glumae MA13 from carbon sources and industrial byproducts related to sugarcane biorefineries: sucrose, xylose, molasses, vinasse, bagasse hydrolysate, yeast extract, yeast autolysate, and inactivated dry yeast besides different inorganic nitrogen sources. Sugarcane molasses free of pre-treatment was the best carbon source, even compared to pure sucrose, with intracellular polymer accumulation values of 41.1–46.6% cell dry weight. Whereas, xylose and bagasse hydrolysate were poor inducers of microbial growth and polymer synthesis, the addition of 25% (v/v) sugarcane vinasse to the culture media containing molasses was not deleterious and resulted in a statistically similar maximum polymer content of 44.8% and a maximum PHA yield of 0.18 g/g, at 34°C and initial pH of 6.5, which is economic and ecologically interesting to save water required for the industrial processes and especially to offer a fermentative recycling for this final byproduct from bioethanol industry, as an alternative to its inappropriate disposal in water bodies and soil contamination. Ammonium sulfate was better even than tested organic nitrogen sources to trigger the PHA synthesis with polymer content ranging from 29.7 to 44.8%. GC-MS analysis showed a biopolymer constituted mainly of poly(3-hydroxybutyrate) although low fractions of 3-hydroxyvalerate monomer were achieved, which were not higher than 1.5 mol% free of copolymer precursors. B. glumae MA13 has been demonstrated to be adapted to synthesize bioplastics from different sugarcane feedstocks and corroborates to support a biorefinery concept with value-added green chemicals for the sugarcane productive chain with additional ecologic benefits into a sustainable model.

Effect of Pith/Fiber Separation, Binders and Hybridization on Energy Density and Physical Properties of Bagasse Briquettes.

Improvements on energy density of loose biomass such as sugarcane feedstock is crucial in the technology of biomass energy conversion and generation. South Africa is one of the producers and refiners of sugarcane. High energy density of sugarcane bagasse biomass through separation and briquetting is imperative in developing adequate streams and quality energy generation from sugarcane upstream milling processes. Unseparated bagasse and separated fractions of fiber and pith possess energy contents of about: 16.14 MJ/kg, 17.73 MJ/kg and 15.74 MJ/kg respectively. Fiber fractions have high energy content than bagasse and pith which demonstrates that pith fraction from bagasse lowers energy density. However, the use of starch and PVA (Polyvinyl Alcohol) as binders during briquetting contributed no significant difference in the overall energy density of the biomass briquettes produced. In the same vein, the addition of 50% charcoal as the hybrid component significantly improves the energy density and the physical properties of briquettes, biomass fractions of bagasse, fiber and pith to: 19.43 MJ/kg, 19.57 MJ/kg and 18.37 MJ/kg respectively. Fiber fraction remains the biomass fraction with highest energy content as compared to other fractions. After briquetting and drying of briquettes to moisture content below 12%, there was a significant improvement on the burning rate, briquetting, binder, hybridization which does improve the biomass briquettes characteristics. Separation of bagasse is crucial under certain conditions since there are no significance differences in the energy density of bagasse fractions. However, the use of PVA and charcoal does pose the necessity of bagasse separation from its fractions for briquetting.

Saccharification of Agricultural Lignocellulosic Feedstocks by Endogenous and Symbiotic Cellulases from the Subterranean Termites

This study investigated the protein fraction-level in vitro and in vivo saccharification potential to biofuel producing feedstocks by the guts of two geographically different termite species. The focus was (i) to measure saccharification potential of feedstocks with respect to control diet (filter paper) by termites’ gut of Reticulitermes flavipes and Heterotermes indicola , (ii) evaluate gut lignocellulase activities after no-choice feeding (iii) to determine impacts of feedstock on foraging activities and survival behavior. Sugarcane bagasse, pinewood, cottonwood and corn stovers were saccharified at significantly high level as compared to control diet and rice husk. The gut protein extract from both termite species saccharified all lignocellulose material regardless of feedstock loading. However, R. flavipes showed significantly (p<0.05) high saccharification potential than H. indicola . Consumption of the sugarcane bagasse, pinewood and corn stover was maximum by R. flavipes , whereas, H. indicola exposed cottonwood and sugarcane feedstocks as most palatable food source with 100% survivability. Hypothesis of this study was that feeding on various feedstocks will show variable impacts on enzyme activities, since an adaptive mechanism enables the termites and their endosymbionts for optimized consumption of variable food source. Results supported “diet adaptation” hypothesis by indicating β- glucosidase, exoglucanase and xylanase activities significantly highest for sugarcane bagasse, pinewood and cottonwood as compared to rice husk and control diets in both termite species. These results are important in perspective of physiological changes in termites that lead to gut microbial environments changes and 100% survivability on exclusive sugarcane bagasse, pinewood and cottonwood feedstocks.

Dynamics of microbial contaminants is driven by selection during ethanol production.

Brazil is the second largest ethanol producer in the world and largest using sugarcane feedstock. Bacteria contamination is one of the most important issues faced by ethanol producers that seek to increase production efficiency. Each step of production is a selection event due to the environmental and biological changes that occur. Therefore, we evaluated the influence of the selection arising from the ethanol production process on diversity and composition of bacteria. Our objectives were to test two hypotheses, (1) that species richness will decrease during the production process and (2) that lactic acid bacteria will become dominant with the advance of ethanol production. Bacterial community assemblage was accessed using 16S rRNA gene sequencing from 19 sequential samples. Temperature is of great importance in shaping microbial communities. Species richness increased between the decanter and must steps of the process. Low Simpson index values were recorded at the fermentation step, indicating a high dominance of Lactobacillus. Interactions between Lactobacillus and yeast may be impairing the efficiency of industrial ethanol production.

A Case Study of Genomic Instability in an Industrial Strain of Saccharomyces cerevisiae.

The Saccharomyces cerevisiae strain JAY270/PE2 is a highly efficient biocatalyst used in the production of bioethanol from sugarcane feedstock. This strain is heterothallic and diploid, and its genome is characterized by abundant structural and nucleotide polymorphisms between homologous chromosomes. One of the reasons it is favored by many distilleries is that its cells do not normally aggregate, a trait that facilitates cell recycling during batch-fed fermentations. However, long-term propagation makes the yeast population vulnerable to the effects of genomic instability, which may trigger the appearance of undesirable phenotypes such as cellular aggregation. In pure cultures of JAY270, we identified the recurrent appearance of mutants displaying a mother-daughter cell separation defect resulting in rough colonies in agar media and fast sedimentation in liquid culture. We investigated the genetic basis of the colony morphology phenotype and found that JAY270 is heterozygous for a frameshift mutation in the ACE2 gene (ACE2/ace2-A7), which encodes a transcriptional regulator of mother-daughter cell separation. All spontaneous rough colony JAY270-derived isolates analyzed carried copy-neutral loss-of-heterozygosity (LOH) at the region of chromosome XII where ACE2 is located (ace2-A7/ace2-A7). We specifically measured LOH rates at the ACE2 locus, and at three additional chromosomal regions in JAY270 and in a conventional homozygous diploid laboratory strain. This direct comparison showed that LOH rates at all sites were quite similar between the two strain backgrounds. In this case study of genomic instability in an industrial strain, we showed that the JAY270 genome is dynamic and that structural changes to its chromosomes can lead to new phenotypes. However, our analysis also indicated that the inherent level of genomic instability in this industrial strain is normal relative to a laboratory strain. Our work provides an important frame of reference to contextualize the interpretation of instability processes observed in the complex genomes of industrial yeast strains.

Scenarios for bioethanol production in Indonesia: How can we meet mandatory blending targets?

This study investigates the potential of bioethanol production and fossil fuel substitution using sugarcane feedstock in Indonesia. Current production practices, government biofuel policies (esp. mandatory blending targets), and sugar self-sufficiency are simulated to project the total potential of fuel ethanol and land requirements in the timeframe between 2015 and 2025. At present conditions, 450 million liters bioethanol can be annually produced in Indonesia using sugarcane molasses, a low-value co-product. This gives only a marginal contribution equivalent to 1% of the total gasoline consumption in 2015. The study examines the ethanol production potential after domestic sugar self-sufficiency is achieved by 2020. In 2015, 0.71 Mha land were required for sugarcane cultivation in order to meet a 2% blend mandate i.e. 0.68 billion liters (BL) ethanol using only cane-molasses. Juice ethanol is needed to meet the blending targets set for 2020 (i.e., 4.45 BL ethanol) and 2025 (i.e., 11.48 BL ethanol). This translates into sugarcane feedstock obtained from 1.60 Mha to 2.76 Mha land, respectively. The study also evaluates how improved resource efficiency can be achieved, exploring the bioelectricity production potential from sugarcane biomass, improvements in yields, and modernization of sugarcane mills. The results highlight how the use of established technologies and production methods can help develop agro-industries in the sugar ethanol segment of Indonesia.

Two‐Year Growth Cycle Sugarcane Crop Parameter Attributes and Their Application in Modeling

The renewed interest in the use of sugarcane (Saccharin officinarum L.) for biofuel could provide a viable market for potential Hawaiian sugarcane feedstock producers. In Hawaii, sugarcane is grown as an irrigated 2‐yr cycle crop. There is however little information on crop parameter attributes of 2‐yr cycle sugarcane. This field study on Maui, Hawaii, analyzed the relationship between sugarcane biomass accumulation and specific crop parameters. Overall, the high dry biomass yield (80.20 Mg ha−1) was the result of a high leaf area index (LAI, 7.50) and radiation use efficiency (RUE, 2.06 g MJ−1. The crop growth rate was highly correlated to LAI (R2, 0.86), and a light extinction coefficient (k) of 0.53 was estimated. Stalk density was estimated at 18 stalks m−2, with a maximum plant height of 3.6 m, and a rooting depth exceeding 2.0 m. When the crop parameters were incorporated into a biological model of Agricultural Land Management Alternatives with Numerical Assessment Criteria (ALMANAC) the model accurately simulated sugarcane yields across seven different soil types and multiple management scenarios of applied irrigation water, N and P fertilizer inputs and various planting and harvest dates. The mean simulation percent (%) errors ranged from –6.4% to 1.8%, while the calculated Fisher's paired t test of 1.41 with 39 degrees of freedom, showed no significant differences (P ≥ 0.05) between measured and simulated yields. The ALMANAC model should be useful as a decision support tool for evaluating sugarcane management alternatives that maximize yields while optimizing water, N and P inputs.

Saccharomyces cerevisiae transcriptional reprograming due to bacterial contamination during industrial scale bioethanol production.

BackgroundThe bioethanol production system used in Brazil is based on the fermentation of sucrose from sugarcane feedstock by highly adapted strains of the yeast Saccharomyces cerevisiae. Bacterial contaminants present in the distillery environment often produce yeast-bacteria cellular co-aggregation particles that resemble yeast-yeast cell adhesion (flocculation). The formation of such particles is undesirable because it slows the fermentation kinetics and reduces the overall bioethanol yield.ResultsIn this study, we investigated the molecular physiology of one of the main S. cerevisiae strains used in Brazilian bioethanol production, PE-2, under two contrasting conditions: typical fermentation, when most yeast cells are in suspension, and co-aggregated fermentation. The transcriptional profile of PE-2 was assessed by RNA-seq during industrial scale fed-batch fermentation. Comparative analysis between the two conditions revealed transcriptional profiles that were differentiated primarily by a deep gene repression in the co-aggregated samples. The data also indicated that Lactobacillus fermentum was likely the main bacterial species responsible for cellular co-aggregation and for the high levels of organic acids detected in the samples.ConclusionsHere, we report the high-resolution gene expression profiling of strain PE-2 during industrial-scale fermentations and the transcriptional reprograming observed under co-aggregation conditions. This dataset constitutes an important resource that can provide support for further development of this key yeast biocatalyst.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-015-0196-6) contains supplementary material, which is available to authorized users.

Impact of Sugarcane Renewable Fuel on In-Use Gaseous and Particulate Matter Emissions from a Marine Vessel

In-use emissions aboard a Stalwart class vessel, the T/S State of Michigan, were measured from a four-stroke marine diesel generator operating on two fuels: ultra-low-sulfur diesel (ULSD) fuel and ULSD mixed with Amyris renewable diesel (S33; 33% by volume) produced from sugarcane feedstocks with 67% by volume ULSD. Measurements followed the International Organization for Standardization (ISO) 8178 procedures and protocols. Gaseous emissions reported include nitrogen oxides (NOx), carbon monoxide (CO), and carbon dioxide (CO2), while reported particulate matter (PM) emissions include PM2.5 mass, elemental carbon (EC), and organic carbon (OC). Overall, a 4% reduction in NOx emissions, a 10% increase in CO, and a 2% increase in CO2 were observed with S33. For PM, no statistically significant differences were seen with S33. PM2.5 was dominated by OC for both fuels. Overall, there was a 26% reduction in EC and an 8% reduction in OC with S33.

Lignification in Sugarcane: Biochemical Characterization, Gene Discovery, and Expression Analysis in Two Genotypes Contrasting for Lignin Content

Sugarcane (Saccharum spp.) is currently one of the most efficient crops in the production of first-generation biofuels. However, the bagasse represents an additional abundant lignocellulosic resource that has the potential to increase the ethanol production per plant. To achieve a more efficient conversion of bagasse into ethanol, a better understanding of the main factors affecting biomass recalcitrance is needed. Because several studies have shown a negative effect of lignin on saccharification yield, the characterization of lignin biosynthesis, structure, and deposition in sugarcane is an important goal. Here, we present, to our knowledge, the first systematic study of lignin deposition during sugarcane stem development, using histological, biochemical, and transcriptional data derived from two sugarcane genotypes with contrasting lignin contents. Lignin amount and composition were determined in rind (outer) and pith (inner) tissues throughout stem development. In addition, the phenolic metabolome was analyzed by ultra-high-performance liquid chromatography-mass spectrometry, which allowed the identification of 35 compounds related to the phenylpropanoid pathway and monolignol biosynthesis. Furthermore, the Sugarcane EST Database was extensively surveyed to identify lignin biosynthetic gene homologs, and the expression of all identified genes during stem development was determined by quantitative reverse transcription-polymerase chain reaction. Our data provide, to our knowledge, the first in-depth characterization of lignin biosynthesis in sugarcane and form the baseline for the rational metabolic engineering of sugarcane feedstock for bioenergy purposes.