Lignocellulose conversion for biofuel: a new pretreatment greatly improves downstream biocatalytic hydrolysis of various lignocellulosic materials

Background

Lignocellulosic biomass is an attractive renewable resource for future liquid transport fuel. Efficient and cost-effective production of bioethanol from lignocellulosic biomass depends on the development of a suitable pretreatment system. The aim of this study is to investigate a new pretreatment method that is highly efficient and effective for downstream biocatalytic hydrolysis of various lignocellulosic biomass materials, which can accelerate bioethanol commercialization.

Results

The optimal conditions for the hydrogen peroxide–acetic acid (HPAC) pretreatment were 80 °C, 2 h, and an equal volume mixture of H₂O₂ and CH₃COOH. Compared to organo-solvent pretreatment under the same conditions, the HPAC pretreatment was more effective at increasing enzymatic digestibility. After HPAC treatment, the composition of the recovered solid was 74.0 % cellulose, 20.0 % hemicelluloses, and 0.9 % lignin. Notably, 97.2 % of the lignin was removed with HPAC pretreatment. Fermentation of the hydrolyzates by S. cerevisiae resulted in 412 mL ethanol kg^?1 of biomass after 24 h, which was equivalent to 85.0 % of the maximum theoretical yield (based on the amount of glucose in the raw material).

Conclusion

The newly developed HPAC pretreatment was highly effective for removing lignin from lignocellulosic cell walls, resulting in enhanced enzymatic accessibility of the substrate and more efficient cellulose hydrolysis. This pretreatment produced less amounts of fermentative inhibitory compounds. In addition, HPAC pretreatment enables year-round operations, maximizing utilization of lignocellulosic biomass from various plant sources.

     

Optimization of NaOH-catalyzed steam pretreatment of empty fruit bunch

Background

Empty fruit bunch (EFB) has many advantages, including its abundance, the fact that it does not require collection, and its year-round availability as a feedstock for bioethanol production. But before the significant costs incurred in ethanol production from lignocellulosic biomass can be reduced, an efficient sugar fractionation technology has to be developed. To that end, in the present study, an NaOH-catalyzed steam pretreatment process was applied in order to produce ethanol from EFB more efficiently.

Results

The EFB pretreatment conditions were optimized by application of certain pretreatment variables such as, the NaOH concentrations in the soaking step and, in the steam step, the temperature and time. The optimal conditions were determined by response surface methodology (RSM) to be 3% NaOH for soaking and 160°C, 11 min 20 sec for steam pretreatment. Under these conditions, the overall glucan recovery and enzymatic digestibility were both high: the glucan and xylan yields were 93% and 78%, respectively, and the enzymatic digestibility was 88.8% for 72 h using 40 FPU/g glucan. After simultaneous saccharification and fermentation (SSF), the maximum ethanol yield and concentration were 0.88 and 29.4 g/l respectively.

Conclusions

Delignification (>85%) of EFB was an important factor in enzymatic hydrolysis using CTec2. NaOH-catalyzed steam pretreatment, which can remove lignin efficiently and requires only a short reaction time, was proven to be an effective pretreatment technology for EFB. The ethanol yield obtained by SSF, the key parameter determining the economics of ethanol, was 18% (w/w), equivalent to 88% of the theoretical maximum yield, which is a better result than have been reported in the relevant previous studies.

     

Integrating sugarcane molasses into sequential cellulosic biofuel production based on SSF process of high solid loading

Background

Sugarcane bagasse (SCB) is one of the most promising lignocellulosic biomasses for use in the production of biofuels. However, bioethanol production from pure SCB fermentation is still limited by its high process cost and low fermentation efficiency. Sugarcane molasses, as a carbohydrate-rich biomass, can provide fermentable sugars for ethanol production. Herein, to reduce high processing costs, molasses was integrated into lignocellulosic ethanol production in batch modes to improve the fermentation system and to boost the final ethanol concentration and yield.

Results

The co-fermentation of pretreated SCB and molasses at ratios of 3:1 (mixture A) and 1:1 (mixture B) were conducted at solid loadings of 12% to 32%, and the fermentation of pretreated SCB alone at the same solid loading was also compared. At a solid loading of 32%, the ethanol concentrations of 64.10 g/L, 74.69 g/L, and 75.64 g/L were obtained from pure SCB, mixture A, and mixture B, respectively. To further boost the ethanol concentration, the fermentation of mixture B (1:1), with higher solid loading from 36 to 48%, was also implemented. The highest ethanol concentration of 94.20 g/L was generated at a high solid loading of 44%, with an ethanol yield of 72.37%. In addition, after evaporation, the wastewater could be converted to biogas by anaerobic digestion. The final methane production of 312.14 mL/g volatile solids (VS) was obtained, and the final chemical oxygen demand removal and VS degradation efficiency was 85.9% and 95.9%, respectively.

Conclusions

Molasses could provide a good environment for the growth of yeast and inoculum. Integrating sugarcane molasses into sequential cellulosic biofuel production could improve the utilization of biomass resources.

     

A new approach to recycle oxalic acid during lignocellulose pretreatment for xylose production

Background

Dilute oxalic acid pretreatment has drawn much attention because it could selectively hydrolyse the hemicellulose fraction during lignocellulose pretreatment. However, there are few studies focusing on the recovery of oxalic acid. Here, we reported a new approach to recycle oxalic acid used in pretreatment via ethanol extraction.

Results

The highest xylose content in hydrolysate was 266.70 mg xylose per 1 g corncob (85.0% yield), which was achieved using 150 mmol/L oxalic acid under the optimized treatment condition (140 °C, 2.5 h). These pretreatment conditions were employed to the subsequent pretreatment using recycled oxalic acid. Oxalic acid in the hydrolysate could be recycled according to the following steps: (1) water was removed via evaporation and vacuum drying, (2) ethanol was used to extract oxalic acid in the remaining mixture, and (3) oxalic acid and ethanol were separated by reduced pressure evaporation. The total xylose yields could be stabilized by intermittent adding oxalic acid, and the yields were in range of 46.7–64.3% in this experiment.

Conclusions

This sustainable approach of recycling and reuse of oxalic acid has a significant potential application for replacing traditional dilute mineral acid pretreatment of lignocellulose, which could contribute to reduce CO₂ emissions and the cost of the pretreatment.

     

Biomass accessibility analysis using electron tomography

Background

Substrate accessibility to catalysts has been a dominant theme in theories of biomass deconstruction. However, current methods of quantifying accessibility do not elucidate mechanisms for increased accessibility due to changes in microstructure following pretreatment.

Results

We introduce methods for characterization of surface accessibility based on fine-scale microstructure of the plant cell wall as revealed by 3D electron tomography. These methods comprise a general framework, enabling analysis of image-based cell wall architecture using a flexible model of accessibility. We analyze corn stover cell walls, both native and after undergoing dilute acid pretreatment with and without a steam explosion process, as well as AFEX pretreatment.

Conclusion

Image-based measures provide useful information about how much pretreatments are able to increase biomass surface accessibility to a wide range of catalyst sizes. We find a strong dependence on probe size when measuring surface accessibility, with a substantial decrease in biomass surface accessibility to probe sizes above 5–10 nm radius compared to smaller probes.

     

Exploring grape marc as trove for new thermotolerant and inhibitor-tolerant <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> strains for second-generation bioethanol production

Background

Robust yeasts with high inhibitor, temperature, and osmotic tolerance remain a crucial requirement for the sustainable production of lignocellulosic bioethanol. These stress factors are known to severely hinder culture growth and fermentation performance.

Results

Grape marc was selected as an extreme environment to search for innately robust yeasts because of its limited nutrients, exposure to solar radiation, temperature fluctuations, weak acid and ethanol content. Forty newly isolated Saccharomyces cerevisiae strains gave high ethanol yields at 40°C when inoculated in minimal media at high sugar concentrations of up to 200 g/l glucose. In addition, the isolates displayed distinct inhibitor tolerance in defined broth supplemented with increasing levels of single inhibitors or with a cocktail containing several inhibitory compounds. Both the fermentation ability and inhibitor resistance of these strains were greater than those of established industrial and commercial S. cerevisiae yeasts used as control strains in this study. Liquor from steam-pretreated sugarcane bagasse was used as a key selective condition during the isolation of robust yeasts for industrial ethanol production, thus simulating the industrial environment. The isolate Fm17 produced the highest ethanol concentration (43.4 g/l) from the hydrolysate, despite relatively high concentrations of weak acids, furans, and phenolics. This strain also exhibited a significantly greater conversion rate of inhibitory furaldehydes compared with the reference strain S. cerevisiae 27P. To our knowledge, this is the first report describing a strain of S. cerevisiae able to produce an ethanol yield equal to 89% of theoretical maximum yield in the presence of high concentrations of inhibitors from sugarcane bagasse.

Conclusions

This study showed that yeasts with high tolerance to multiple stress factors can be obtained from unconventional ecological niches. Grape marc appeared to be an unexplored and promising substrate for the isolation of S. cerevisiae strains showing enhanced inhibitor, temperature, and osmotic tolerance compared with established industrial strains. This integrated approach of selecting multiple resistant yeasts from a single source demonstrates the potential of obtaining yeasts that are able to withstand a number of fermentation-related stresses. The yeast strains isolated and selected in this study represent strong candidates for bioethanol production from lignocellulosic hydrolysates.

     

Anaerobic microplate assay for direct microbial conversion of switchgrass and Avicel using <Emphasis Type="Italic">Clostridium thermocellum</Emphasis>

Objective

To develop and prototype a high-throughput microplate assay to assess anaerobic microorganisms and lignocellulosic biomasses in a rapid, cost-effective screen for consolidated bioprocessing potential.

Results

Clostridium thermocellum parent Δhpt strain deconstructed Avicel to cellobiose, glucose, and generated lactic acid, formic acid, acetic acid and ethanol as fermentation products in titers and ratios similar to larger scale fermentations confirming the suitability of a plate-based method for C. thermocellum growth studies. C. thermocellum strain LL1210, with gene deletions in the key central metabolic pathways, produced higher ethanol titers in the Consolidated Bioprocessing (CBP) plate assay for both Avicel and switchgrass fermentations when compared to the Δhpt strain.

Conclusion

A prototype microplate assay system is developed that will facilitate high-throughput bioprospecting for new lignocellulosic biomass types, genetic variants and new microbial strains for bioethanol production.

     

Strategies to assess and optimize stability of endogenous amines during cerebrospinal fluid sampling

Introduction

Metabolic profiling of cerebrospinal fluid (CSF) is a promising technique for studying brain diseases. Measurements should reflect the in vivo situation, so ex vivo metabolism should be avoided.

Objective

To investigate the effects of temperature (room temperature vs. 4 °C), centrifugation and ethanol, as anti-enzymatic additive during CSF sampling on concentrations of glutamic acid, glutamine and other endogenous amines.

Methods

CSF samples from 21 individuals were processed using five different protocols. Isotopically-labeled alanine, isoleucine, glutamine, glutamic acid and dopamine were added prior to sampling to trace any degradation. Metabolomics analysis of endogenous amines, isotopically-labeled compounds and degradation products was performed with a validated LC–MS method.

Results

Thirty-six endogenous amines were quantified. There were no statistically significant differences between sampling protocols for 31 out of 36 amines. For GABA there was primarily an effect of temperature (higher concentrations at room temperature than at 4 °C) and a small effect of ethanol (lower concentrations if added) due to possible degradation. O-phosphoethanolamine concentrations were also lower when ethanol was added. Degradation of isotopically-labeled compounds (e.g. glutamine to glutamic acid) was minor with no differences between protocols.

Conclusion

Most amines can be considered stable during sampling, provided that samples are cooled immediately to 4 °C, centrifuged, and stored at ??80 °C within 2 h. The effect of ethanol addition for more unstable metabolites needs further investigation. This was the first time that labeled compounds were used to monitor ex vivo metabolism during sampling. This is a useful strategy to study the stability of other metabolites of interest.

     

Corneal Collagen Cross-Linking for the Management of Mycotic Keratitis

Purpose

To evaluate the efficiency of corneal collagen cross-linking (CXL) in addition to topical voriconazole in cases with mycotic keratitis.

Design

Retrospective case series in a tertiary university hospital.

Participants

CXL was performed on 13 patients with mycotic keratitis who presented poor or no response to topical voriconazole treatment.

Methods

The clinical features, symptoms, treatment results and complications were recorded retrospectively. The corneal infection was graded according to the depth of infection into the stroma (from grade 1 to grade 3). The visual analogue scale was used to calculate the pain score before and 2 days after surgery.

Main Outcome Measures

Grade of the corneal infection.

Results

Mean age of 13 patients (6 female and 7 male) was 42.4 ± 17.7 years (20–74 years). Fungus was demonstrated in culture (eight patients) or cytological examination (five patients). Seven of the 13 patients (54%) were healed with topical voriconazole and CXL adjuvant treatment in 26 ± 10 days (15–40 days). The remaining six patients did not respond to CXL treatment; they initially presented with higher grade ulcers. Pre- and post-operative pain score values were 8 ± 0.8 and 3.5 ± 1, respectively (p < 0.05).

Conclusions

The current study suggests that adjunctive CXL treatment is effective in patients with small and superficial mycotic ulcers. These observations require further research by large randomized clinical trials.

     

An NIRS-based assay of chemical composition and biomass digestibility for rapid selection of Jerusalem artichoke clones

Background

High-throughput evaluation of lignocellulosic biomass feedstock quality is the key to the successful commercialization of bioethanol production. Currently, wet chemical methods for the determination of chemical composition and biomass digestibility are expensive and time-consuming, thus hindering comprehensive feedstock quality assessments based on these biomass specifications. To find the ideal bioethanol feedstock, we perform a near-infrared spectroscopic (NIRS) assay to rapidly and comprehensively analyze the chemical composition and biomass digestibility of 59 Jerusalem artichoke (Helianthus tuberosus L., abbreviated JA) clones collected from 24 provinces in six regions of China.

Results

The distinct geographical distribution of JA accessions generated varied chemical composition as well as related biomass digestibility (after soluble sugars extraction and mild alkali pretreatment). Notably, the soluble sugars, cellulose, hemicellulose, lignin, ash, and released hexoses, pentoses, and total carbohydrates were rapidly and perfectly predicted by partial least squares regression coupled with model population analyses (MPA), which exhibited significantly higher predictive performance than controls. Subsequently, grey relational grade analysis was employed to correlate chemical composition and biomass digestibility with feedstock quality score (FQS), resulting in the assignment of tested JA clones to five feedstock quality grades (FQGs). Ultimately, the FQGs of JA clones were successfully classified using partial least squares-discriminant analysis model coupled with MPA, attaining a significantly higher correct rate of 97.8% in the calibration subset and 91.1% in the validation subset.

Conclusions

Based on the diversity of JA clones, the present study has not only rapidly and precisely examined the biomass composition and digestibility with MPA-optimized NIRS models but has also selected the ideal JA clones according to FQS. This method provides a new insight into the selection of ideal bioethanol feedstock for high-efficiency bioethanol production.

     

Embedded rock fragments affect alpine steppe plant growth,soil carbon and nitrogen in the northern Tibetan Plateau

Background and Aims

Rock fragments within topsoil have important effects on soil properties and plant growth. This study mainly aimed to investigate the relationships between rock fragments, soil carbon (C) and nitrogen (N) densities and vegetation biomass in an alpine steppe.

Methods

Rock fragments, plant and soil samples were collected from four topographic positions (top, upper, lower, and bottom) on a hillslope.

Results

Volumetric rock fragment content within the 0–30 cm soil profile varied from 17.8 to 30.5%, the upper position value was significantly greater (P < 0.05) than those at other positions. The highest aboveground biomass was observed at the lower position (921 kg ha^?1), while the highest belowground biomass within the 0–30 cm profile was found at the upper position (4460 kg ha^?1). More fine earth and plant litter input accompanied by lower C and N losses induced by rainfall erosion resulted in higher soil organic C and total N densities (28.6 Mg C ha^?1 and 2.87 Mg N ha^?1) at the lower position.

Conclusions

Rock fragments may promote root growth but limit aboveground biomass production, and can therefore change the biomass distribution pattern. Our findings provide more evidence for scientifically assessing alpine steppe productivity.

     

A novel ethanol-tolerant laccase,Tvlac, from <Emphasis Type="Italic">Trametes versicolor</Emphasis>

Objectives

To produce and characterize novel laccases with ethanol tolerance from Trametes versicolor using agriculture by-products as energy source.

Results

Trametes versicolor 1017 produces two laccase isoenzymes with a total activity of 10 U ml^?1 within 8 days when using wheat bran and peanut powder as energy sources in liquid culture medium. A novel isoenzyme, named Tvlac, was identified, purified and characterized. Its optimum pH and temperature were from 4.5 to 5 and 55 to 60 °C, respectively. Its activity was stimulated by ethanol at 10 % (v/v) which increased the V ₀.

Conclusions

The biochemical properties of Tvlac substantiate the potential of this enzyme for applications under an aqueous ethanol mixture environment.

     

A two-stage system coupling hydrolytic acidification with algal microcosms for treatment of wastewater from the manufacture of acrylonitrile butadiene styrene (ABS) resin

Objectives

To demonstrate the effectiveness of a novel two-stage system coupling hydrolytic acidification with algal microcosms for the treatment of acrylonitrile butadiene styrene (ABS) resin-manufacturing wastewater.

Results

After hydrolytic acidification, the BOD₅/COD ratio increased from 0.22 to 0.56, showing improved biodegradability of the wastewater. Coupled with hydrolytic acidification, the algal microcosms showed excellent capability of in-depth removal of COD, NH₃–N and phosphorus with removal rates 83, 100, and 89%, respectively, and aromatic pollutants, including benzene, were almost completely removed. The biomass concentration of Chlorella sp. increased from 5 × 10⁶ to 2.1 × 10⁷ cells/ml after wastewater treatment.

Conclusions

This two-stage coupling system achieved deep cleaning of the benzene-containing petrochemical wastewater while producing greater algae biomass resources at low cost.

     

A novel cost-effective technology to convert sucrose and homocelluloses in sweet sorghum stalks into ethanol

Background

Sweet sorghum is regarded as a very promising energy crop for ethanol production because it not only supplies grain and sugar, but also offers lignocellulosic resource. Cost-competitive ethanol production requires bioconversion of all carbohydrates in stalks including of both sucrose and lignocellulose hydrolyzed into fermentable sugars. However, it is still a main challenge to reduce ethanol production cost and improve feasibility of industrial application. An integration of the different operations within the whole process is a potential solution.

Results

An integrated process combined advanced solid-state fermentation technology (ASSF) and alkaline pretreatment was presented in this work. Soluble sugars in sweet sorghum stalks were firstly converted into ethanol by ASSF using crushed stalks directly. Then, the operation combining ethanol distillation and alkaline pretreatment was performed in one distillation-reactor simultaneously. The corresponding investigation indicated that the addition of alkali did not affect the ethanol recovery. The effect of three alkalis, NaOH, KOH and Ca(OH)₂ on pretreatment were investigated. The results indicated the delignification of lignocellulose by NaOH and KOH was more significant than that by Ca(OH)₂, and the highest removal of xylan was caused by NaOH. Moreover, an optimized alkali loading of 10% (w/w DM) NaOH was determined. Under this favorable pretreatment condition, enzymatic hydrolysis of sweet sorghum bagasse following pretreatment was investigated. 92.0% of glucan and 53.3% of xylan conversion were obtained at enzyme loading of 10 FPU/g glucan. The fermentation of hydrolyzed slurry was performed using an engineered stain, Zymomonas mobilis TSH-01. A mass balance of the overall process was calculated, and 91.9 kg was achieved from one tonne of fresh sweet sorghum stalk.

Conclusions

A low energy-consumption integrated technology for ethanol production from sweet sorghum stalks was presented in this work. Energy consumption for raw materials preparation and pretreatment were reduced or avoided in our process. Based on this technology, the recalcitrance of lignocellulose was destructed via a cost-efficient process and all sugars in sweet sorghum stalks lignocellulose were hydrolysed into fermentable sugars. Bioconversion of fermentable sugars released from sweet sorghum bagasse into different products except ethanol, such as butanol, biogas, and chemicals was feasible to operate under low energy-consumption conditions.

     

Direct electrospinning of poly(vinyl butyral) onto human dermal fibroblasts using a portable device

Objective

To demonstrate that uniform poly(vinyl butyral) (PVB) fibres can be safely electrospun onto a monolayer of human dermal fibroblasts using a portable device.

Results

PVB in solvent mixtures containing various amounts of ethanol and water was electrospun. Six percent (weight-to-volume ratio) PVB in a 9:1 ethanol:water ratio was the solution with the highest content in water that could be electrospun into consistent fibres with an average diameter of 0.9 μm (± 0.1 μm). Four and five percent PVB solutions created beaded fibres. A 8:2 ethanol:water solution lead to microbead formation while a 7:3 ethanol:water mix failed to fully dissolve. The selected solution was successfully electrospun onto a monolayer of human dermal fibroblasts and the process had no significant effect (p < 0.05) on cell viability compared to the control without fibres.

Conclusions

PVB–ethanol–water solutions could be electrospun without damaging the exposed cell layer. However, further work is required to demonstrate the long-term effect of PVB as a wound healing material.

     

Fertilization,soil and plant community characteristics determine soil microbial activity in managed temperate grasslands

Background and aims

Contaminated soils can impede germination and growth of selected plant species, restricting effective phytoremediation strategies. The purpose of the present study was to enhance the germination and growth of saltgrass [Distichlis spicata (L.) Greene] by evaluating the efficacy of certain seed pretreatments and soil amendments.

Methods

Ten seed pretreatment methods, two amendments, three soil depths and five saline levels were tested under greenhouse conditions.

Results

Saltgrass germination and growth were negatively correlated with increasing salinity levels when NaCl > 85.6 mM. Among ten seed pretreatments (stratification + Proxy 24 h, hot water + Proxy 24 h, stratification, hot water + Proxy 48 h, Proxy 48 h, Proxy 24 h, hot water, scarification, gibberellins, and KMnO₄), the two best methods were stratification + Proxy 24 h and hot water + Proxy 24 h for enhancing saltgrass germination, with the latter pretreatment being especially useful because of its shorter preparation time and high germination rates. Proxy is a commercial ethephon product. Potting soil (5.0 cm depth) was found to be the best amendment for saltgrass germination and growth in hydrocarbon-contaminated soils.

Conclusion

We conclude that direct seeding of saline soils contaminated with petroleum hydrocarbons is a feasible phytoremediation strategy provided that appropriate seed pretreatments and amendments are utilized.

     

Isolation and characterization of butanol-tolerant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>

Objectives

A new solvent-tolerant species, Staphylococcus aureus, was isolated and characterized during the screening of butanol-tolerant microorganisms.

Results

Three isolates of S. aureus were obtained as contaminants during improvement of butanol tolerance of E. coli K12. Their cell dry weights were 135 % that of K12 in the absence of butanol stress. S. aureus had a growth advantage over K12 when cultured with various concentrations of butanol. It can tolerate up to 3 % (v/v) butanol, while most solventogenic bacteria can tolerate only 2 % (v/v) butanol. The addition of 10–20 g glucose/l enhanced its butanol tolerance. The relative cell biomass of the S. aureus was 71–306 % that of E. coli under 5.5–10 % (v/v) ethanol stress, indicating ethanol resistance.

Conclusions

This is the first study to observe butanol-tolerant S. aureus. As this organism can be genetically manipulated, it could have a wide array of applications.

     

Synergistic effects of mixing hybrid poplar and wheat straw biomass for bioconversion processes

Background

Low cost of raw materials and good process yields are necessary for future lignocellulosic biomass biorefineries to be sustainable and profitable. A low cost feedstock will be diverse, changing as a function of seasonality and price and will most likely be available from multiple sources to the biorefinery. The efficacy of the bioconversion process using mixed biomass, however, has not been thoroughly investigated. Considering the seasonal availability of wheat straw and the year round availability of hybrid poplar in the Pacific Northwest, this study aims to determine the impact of mixing wheat straw and hybrid poplar biomass on the overall sugar production via steam pretreatment and enzymatic saccharification.

Results

Steam pretreatment proved to be effective for processing different mixtures of hybrid poplar and wheat straw. Following SO₂-catalyzed steam explosion pretreatment, on average 22 % more sugar monomers were recovered using mixed feedstock than either single biomass. Improved sugar recovery with mixtures of poplar and wheat straw continued through enzymatic hydrolysis. After steam pretreatment and saccharification, the mixtures showed 20 % higher sugar yields than that produced from hybrid poplar and wheat straw alone.

Conclusions

Blending hybrid poplar and wheat straw resulted in more monomeric sugar recovery and less sugar degradation. This synergistic effect is attributable to interaction of hybrid poplar’s high acetic acid content and the presence of ash supplied by wheat straw. As a consequence on average 20 % more sugar was yielded by using the different biomass mixtures. Combining hybrid poplar and wheat straw enables sourcing of the lowest cost biomass, reduces seasonal dependency, and results in increasing biofuels and chemicals productivity in a cellulosic biorefinery.

     

Does centrifugation matter? Centrifugal force and spinning time alter the plasma metabolome

Background

Centrifugation is an indispensable procedure for plasma sample preparation, but applied conditions can vary between labs.

Aim

Determine whether routinely used plasma centrifugation protocols (1500×g 10 min; 3000×g 5 min) influence non-targeted metabolomic analyses.

Methods

Nuclear magnetic resonance spectroscopy (NMR) and High Resolution Mass Spectrometry (HRMS) data were evaluated with sparse partial least squares discriminant analyses and compared with cell count measurements.

Results

Besides significant differences in platelet count, we identified substantial alterations in NMR and HRMS data related to the different centrifugation protocols.

Conclusion

Already minor differences in plasma centrifugation can significantly influence metabolomic patterns and potentially bias metabolomics studies.