Non-optimal codon usage affects expression, structure and function of clock protein FRQ.

Codon-usage bias has been observed in almost all genomes and is thought to result from selection for efficient and accurate translation of highly expressed genes. Codon usage is also implicated in the control of transcription, splicing and RNA structure. Many genes exhibit little codon-usage bias, which is thought to reflect a lack of selection for messenger RNA translation. Alternatively, however, non-optimal codon usage may be of biological importance. The rhythmic expression and the proper function of the Neurospora FREQUENCY (FRQ) protein are essential for circadian clock function. Here we show that, unlike most genes in Neurospora, frq exhibits non-optimal codon usage across its entire open reading frame. Optimization of frq codon usage abolishes both overt and molecular circadian rhythms. Codon optimization not only increases FRQ levels but, unexpectedly, also results in conformational changes in FRQ protein, altered FRQ phosphorylation profile and stability, and impaired functions in the circadian feedback loops. These results indicate that non-optimal codon usage of frq is essential for its circadian clock function. Our study provides an example of how non-optimal codon usage functions to regulate protein expression and to achieve optimal protein structure and function.

Failure Rates of Base of Thumb Arthritis Surgery: A Systematic Review.

PURPOSE: The purpose of the current review was to estimate failure rates of trapeziometacarpal (TMC) implants and compare against failure rates of nonimplant techniques for surgical treatment of TMC joint (basal thumb joint) arthritis. METHODS: A systematic review was conducted to identify articles reporting on thumb implant arthroplasty and on nonimplant arthroplasty techniques for treatment of base of thumb arthritis in the English literature. The collected data were combined to calculate failure rates per 100 procedure-years. Failure was defined by the requirement for a secondary salvage procedure. The failure rates between different implant and nonimplant arthroplasty groups were compared directly and implants with higher than anticipated failure rates were identified. RESULTS: One hundred twenty-five articles on implant arthroplasty and 33 articles on the outcome of nonimplant surgical arthroplasty of the TMC joint were included. The implant arthroplasty failure rates per 100 procedure-years were total joint replacement (2.4), hemiarthroplasty (2.5), interposition with partial trapezial resection (4.5), interposition with complete trapezial resection (1.7), and interposition with no trapezial resection (4.5). The nonimplant arthroplasty failure rates per 100 procedure-years were: trapeziectomy (0.49), joint fusion (0.52), and trapeziectomy with ligament reconstruction ± tendon interposition (0.23). CONCLUSIONS: Several implant designs (arthroplasties) had high rates of failure due to aseptic loosening, dislocation, and persisting pain. Furthermore, some implants had higher than anticipated failure rates than other implants within each class. Overall, the failure rates of nonimplant techniques were lower than those of implant arthroplasty. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Accelerating settling rates of biosolids lagoons through thermal hydrolysis.

Although the improved dewaterability and digestibility of primary biosolids subjected to thermal hydrolysis has been studied for decades, there are a surprisingly small number of studies exploring the use of this thermal treatment for digested biosolids that are typically left to settle in large settling lagoons. This is likely because of the high capital and operating costs associated with thermal hydrolysis, coupled with the limited applications and value of the resulting products. However, due to the anticipated increases in the amount of generated biosolids combined with issues surrounding potential environmental release and the limited availability of land for additional lagoons, other biosolids management strategies are being explored. Here, we show that thermal hydrolysis at 280 °C for 1 h resulted in 78.2 ±â€¯0.8% settling after 2 h. Furthermore, addition of phosphoric acid to lower the pH of the hydrolysate to pH 3 resulted in increased settling rates, but the final volume of unsettled material after 2 h was statistically similar to the thermally hydrolyzed material without pH adjustment (75.7 ±â€¯2.3%). Remarkably, when the pH of the digested biosolids was adjusted to 3 prior to thermal hydrolysis, a settling rate of 87.3 ±â€¯1.1% was observed after just 15 min. Significantly, the dewaterability of thermally hydrolyzed biosolids was measured in our experiments through natural settling, without the use of external mechanics. Taken together, the data presented in this paper demonstrate that high temperature thermal hydrolysis is a promising method for accelerating the settling rates of digested biosolids and may represent a viable alternative to building and maintaining biosolids lagoons.

Incorporation of whey permeate, a dairy effluent, in ethanol fermentation to provide a zero waste solution for the dairy industry.

This study proposes a novel alternative for utilization of whey permeate, a by-product stream from the dairy industry, in wheat fermentation for ethanol production using Saccharomyces cerevisiae. Whey permeates were hydrolyzed using enzymes to release fermentable sugars. Hydrolyzed whey permeates were integrated into wheat fermentation as a co-substrate or to partially replace process water. Cold starch hydrolysis-based simultaneous saccharification and fermentation was done as per the current industrial protocol for commercial wheat-to-ethanol production. Ethanol production was not affected; ethanol yield efficiency did not change when up to 10% of process water was replaced. Lactic acid bacteria in whey permeate did not negatively affect the co-fermentation or reduce ethanol yield. Whey permeate could be effectively stored for up to 4 wk at 4 °C with little change in lactose and lactic acid content. Considering the global abundance and nutrient value of whey permeate, the proposed strategy could improve economics of the dairy and biofuel sectors, and reduce environmental pollution. Furthermore, our research may be applied to fermentation strategies designed to produce value-added products other than ethanol.

Current evidence for postoperative monitoring of microvascular free flaps: a systematic review.

BACKGROUND: Despite a plethora of monitoring techniques reported in the literature, only a small number of studies directly address clinical relevant end points, such as the flap salvage rate and false-positive rate. METHOD: We conducted a systematic review of current evidence regarding the postoperative monitoring of microvascular free-tissue transfer via extensive electronic and manual search and perusing databases, such as PubMed, Cochrane, American College of Physicians (ACP) Journal Club, Cumulative Index of Nursing and Allied Health Literature (CINAHL), Excerpta Medica Database (EMBASE), and Ovid MEDLINE. The included literature (n = 184 publications) was critically appraised using March 2009 Oxford Centre for Evidence-Based Medicine definitions, focusing on the evidence for the efficacy of each technique in improving the flap salvage rate of compromised flaps. RESULT: There is a paucity of outcome-based studies, with only implanted Doppler probes, near-infrared spectroscopy, laser Doppler flowmetry, quantitative fluorimetry, and digital photography assessment using smartphones having been demonstrated in comparative studies to improve flap salvage rate. Currently, the implantable Doppler probe is the technique with the largest number of comparative studies and case series to demonstrate its effectiveness compared with clinical monitoring. CONCLUSIONS: Future studies need to evaluate the most promising monitoring techniques further with a focus on assessing clinically relevant outcomes, such as the flap salvage rate and the false-positive rate, and not simple clinical series reporting patient and physician satisfaction.

3D-printed haptic "reverse" models for preoperative planning in soft tissue reconstruction: a case report.

In reconstructive surgery, preoperative planning is essential for optimal functional and aesthetic outcome. Creating a three-dimensional (3D) model from two-dimensional (2D) imaging data by rapid prototyping has been used in industrial design for decades but has only recently been introduced for medical application. 3D printing is one such technique that is fast, convenient, and relatively affordable. In this report, we present a case in which a reproducible method for producing a 3D-printed "reverse model" representing a skin wound defect was used for flap design and harvesting. This comprised a 82-year-old man with an exposed ankle prosthesis after serial soft tissue debridements for wound infection. Soft tissue coverage and dead-space filling were planned with a composite radial forearm free flap (RFFF). Computed tomographic angiography (CTA) of the donor site (left forearm), recipient site (right ankle), and the left ankle was performed. 2D data from the CTA was 3D-reconstructed using computer software, with a 3D image of the left ankle used as a "control." A 3D model was created by superimposing the left and right ankle images, to create a "reverse image" of the defect, and printed using a 3D printer. The RFFF was thus planned and executed effectively, without complication. To our knowledge, this is the first report of a mechanism of calculating a soft tissue wound defect and producing a 3D model that may be useful for surgical planning. 3D printing and particularly "reverse" modeling may be versatile options in reconstructive planning, and have the potential for broad application.

Four-Dimensional (4D) Printing: A New Evolution in Computed Tomography-Guided Stereolithographic Modeling. Principles and Application.

BACKGROUND: Over the last decade, image-guided production of three-dimensional (3D) haptic biomodels, or rapid prototyping (RP), has transformed the way surgeons conduct preoperative planning. In contrast to earlier RP techniques such as stereolithography, 3D printing has introduced fast, affordable office-based manufacturing. We introduce the concept of 4D printing for the first time by introducing time as the fourth dimension to 3D printing. METHODS: The bones of the thumb ray are 3D printed during various movements to demonstrate four-dimensional (4D) printing. Principles and validation studies are presented here. RESULTS: 4D computed tomography was performed using "single volume acquisition" technology to reduce the exposure to radiation. Three representative scans of each thumb movement (i.e., abduction, opposition, and key pinch) were selected and then models were fabricated using a 3D printer. For validation, the angle between the first and the second metacarpals from the 4D imaging data and the 4D-printed model was recorded and compared. CONCLUSION: We demonstrate how 4D printing accurately depicts the transition in the position of metacarpals during thumb movement. With a fourth dimension of time, 4D printing delivers complex spatiotemporal anatomical details effortlessly and may substantially improve preoperative planning.

3D volumetric analysis for planning breast reconstructive surgery.

Breast reconstruction plays an integral role in the holistic management of breast cancer, with assessment of breast volume, shape, and projection vital in planning breast reconstruction surgery. Current practice includes two-dimensional (2D) photography and visual estimation in selecting ideal volume and shape of breast implants or soft-tissue flaps. Other objective quantitative means of calculating breast volume have been reported, such as direct anthropomorphic measurements or three-dimensional (3D) photography, but none have proven reliably accurate. We describe a novel approach to volumetric analysis of the breast, through the creation of a haptic, tactile model, or 3D print of scan data. This approach comprises use of a single computed tomography (CT) or magnetic resonance imaging (MRI) scan for volumetric analysis, which we use to compare to simpler estimation techniques, create software-generated 3D reconstructions, calculate, and visualize volume differences, and produce biomodels of the breasts using a 3D printer for tactile appreciation of volume differential. Using the technique described, parenchymal volume was assessed and calculated using CT data. A case report was utilized in a pictorial account of the technique, in which a volume difference of 116 cm(3) was calculated, aiding reconstructive planning. Preoperative planning, including volumetric analysis can be used as a tool to aid esthetic outcomes and attempt to reduce operative times in post-mastectomy breast reconstruction surgery. The combination of accurate volume calculations and the production of 3D-printed haptic models for tactile feedback and operative guidance are evolving techniques in volumetric analysis and preoperative planning in breast reconstruction.

A uvs-5 strain is deficient for a mitofusin gene homologue, fzo1, involved in maintenance of long life span in Neurospora crassa.

Mitochondria are highly dynamic organelles that continuously fuse and divide. To maintain mitochondria, cells establish an equilibrium of fusion and fission events, which are mediated by dynamin-like GTPases. We previously showed that an mus-10 strain, a mutagen-sensitive strain of the filamentous fungus Neurospora crassa, is defective in an F-box protein that is essential for the maintenance of mitochondrial DNA (mtDNA), long life span, and mitochondrial morphology. Similarly, a uvs-5 mutant accumulates deletions within its mtDNA, has a shortened life span, and harbors fragmented mitochondria, the latter of which is indicative of an imbalance between mitochondrial fission and fusion. Since the uvs-5 mutation maps very close to the locus of fzo1, encoding a mitofusin homologue thought to mediate mitochondrial outer membrane fusion, we determined the sequence of the fzo1 gene in the uvs-5 mutant. A single amino acid substitution (Q368R) was found in the GTPase domain of the FZO1 protein. Expression of wild-type FZO1 in the uvs-5 strain rescued the mutant phenotypes, while expression of a mutant FZO1 protein did not. Moreover, when knock-in of the Q368R mutation was performed on a wild-type strain, the resulting mutant displayed phenotypes identical to those of the uvs-5 mutant. Therefore, we concluded that the previously unidentified uvs-5 gene is fzo1. Furthermore, we used immunoprecipitation analysis to show that the FZO1 protein interacts with MUS-10, which suggests that these two proteins may function together to maintain mitochondrial morphology.

Exploring Age-Related Variations in Carpal Bone Volume: Implications for Clinical Practice and Anatomical Understanding.

BACKGROUND: Clinically recognizing the changes in carpal bone volumes and understanding their implications in predicting osteoarthritis (OA) is crucial in clinical practice This study aimed to explore age-related differences in carpal bone volumes across genders, leveraging computed tomography (CT) wrist scans to create 3D surface models of these bones. METHODS: Carpal bone volumes were calculated using the 3D Slicer software from CT scans obtained from Frankston Hospital and additional datasets from Brown and Auckland Universities. The data were statistically processed using Stata V13. Double-sided P-values < .05 were considered statistically significant. The study was conducted in accordance with the ethical standards laid out in the Declaration of Helsinki. RESULTS: A total of 181 patients were analyzed, and 48% of whom were female. A statistically significant positive Spearman correlation (rho = 0.37-0.611, P <.05) was observed between increasing age and the volume of all surveyed carpal bones (scaphoid, lunate, triquetrum, pisiform, hamate, capitate, and trapezium) across genders. Intrauser and interuser reliabilities for 3D Slicer-generated volumes of trapezium and pisiform bones were statistically significant, with Interclass Correlation Coefficient (ICC) values of 0.86 and 0.95, respectively. CONCLUSION: Trapezial volumes increase with age, potentially due to the presence of OA and consequent osteophyte formation. This pattern is more prevalent among older individuals and women. However, the positive correlation between carpal bone volume and age was consistent across all carpal bones and both genders, regardless of OA presence. These findings suggest that carpal bone volume may naturally increase with age, independent of OA-related changes. LEVEL OF EVIDENCE: III, cohort study.

Adapted feeding strategies in fed-batch fermentation improve sugar delivery and ethanol productivity.

Bioethanol is a renewable fuel widely used in road transportation and is generally regarded as a clean energy source. Although fermentation is one of the major processes in bioethanol production, studies on improving its efficiency through operational design are limited, especially compared to other steps (pretreatment and hydrolysis/saccharification). In this study, two adapted feeding strategies, in which feed medium addition (sugar delivery) was adjusted to increase the supply of fermentable sugar, were developed to improve ethanol productivity in 5-L fed-batch fermentation by Saccharomyces cerevisiae. Specifically, a linear adapted feeding strategy was established based on changes in cell biomass, and an exponential adapted feeding strategy was developed based on cell biomass accumulation. By implementing these two feeding strategies, the overall ethanol productivity reached 0.88±0.04 and 0.87±0.06 g/L/h, respectively. This corresponded to ~20% increases in ethanol productivity compared to fixed pulsed feeding operations. Additionally, there was no residual glucose at the end of fermentation, and final ethanol content reached 95±3 g/L under the linear adapted operation and 104±3 g/L under the exponential adapted feeding strategy. No statistical difference was observed in the overall ethanol yield (ethanol-to-sugar ratio) between fixed and adapted feeding strategies (~91%). These results demonstrate that sugar delivery controlled by adapted feeding strategies was more efficient than fixed feeding operations, leading to higher ethanol productivity. Overall, this study provides novel adapted feeding strategies to improve sugar delivery and ethanol productivity. Integration into the current practices of the ethanol industry could improve productivity and reduce production costs of fermentation processes.

Valorization strategies for hazardous proteinaceous waste from rendering production - Recent advances in specified risk materials (SRMs) conversion.

Strict bans on specific risk materials (SRMs) are in place to prevent the spread of bovine spongiform encephalopathy (BSE). SRMs are characterized as tissues in cattle where misfolded proteins, the potential source of BSE infection, are concentrated. As a result of these bans, SRMs must be strictly isolated and disposed of, resulting in great costs for rendering companies. The increasing yield and the landfill of SRMs also exacerbated the burden on the environment. To cope with the emergence of SRMs, novel disposal methods and feasible value-added conversion routes are needed. The focus of this review is on the valorization progress achieved in the conversion of peptides derived from SRMs via an alternative disposal method, thermal hydrolysis. Promising value-added conversion of SRM-derived peptides into tackifiers, wood adhesives, flocculants, and bioplastics, is introduced. The potential conjugation strategies that can be adapted to SRM-derived peptides for desired properties are also critically reviewed. The purpose of this review is to discover a technical platform through which other hazardous proteinaceous waste, SRMs, can be treated as a high-demand feedstock for the production of renewable materials.

Ruminant-Waste Protein Hydrolysates and Their Derivatives as a Bio-Flocculant for Oil Sands Tailing Management.

Reclamation of tailings ponds is a critical issue for the oil industry. After years of consolidation, the slurry in tailings ponds, also known as fluid fine tailings, is mainly comprised of residual bitumen, water, and fine clay particles. To reclaim the lands that these ponds occupy, separation of the solid particles from the liquid phase is necessary to facilitate water removal and recycling. Traditionally, synthetic polymers have been used as flocculants to facilitate this process, but they can have negative environmental consequences. The use of biological polymers may provide a more environmentally friendly approach to flocculation, and eventual soil remediation, due to their natural biodegradability. Peptides derived from specified risk materials (SRM), a proteinaceous waste stream derived from the rendering industry, were investigated to assess their viability for this application. While these peptides could achieve >50% settling within 3 h in bench-scale settling tests using kaolinite tailings, crosslinking peptides with glutaraldehyde greatly improved their flocculation performance, leading to a >50% settling in only 10 min. Settling experiments using materials obtained through different reactant ratios during crosslinking identified a local optimum molar reactant ratio of 1:32 (peptide amino groups to glutaraldehyde aldehyde groups), resulting in 81.6% settling after 48 h. Taken together, these data highlight the novelty of crosslinking waste-derived peptides with glutaraldehyde to generate a value-added bioflocculant with potential for tailings ponds consolidation.

Co-production of ethanol and cellulose nanocrystals through self-cycling fermentation of wood pulp hydrolysate.

A promising approach to help offset production costs for the cellulosic ethanol industry is to improve ethanol productivity while simultaneously generating value-added by-products. This study reports integration of an advanced fermentation approach (self-cycling fermentation) with the production of cellulose nanocrystals. Specifically, wood pulp was enzymatically hydrolyzed to yield dissolved sugars, which were fed to a self-cycling fermentation system for ethanol production, and residual solids were used for cellulose nanocrystals production via acid hydrolysis. Self-cycling fermentation achieved stable ethanol production for 10 cycles with significantly greater productivity than batch operation: ethanol volumetric productivity increased by 63-95% and annual ethanol productivity by 96 ± 5%. Additionally, the enzyme hydrolysis approach employed did not impede ethanol fermentation, and the cellulose nanocrystals generated displayed properties consistent with previous studies. Taken together, these results highlight the potential of this co-production strategy to produce both cellulosic ethanol and cellulose nanocrystals from a single feedstock.

Using Specified Risk Materials-Based Peptides for Oil Sands Fluid Fine Tailings Management.

Fluid fine tailings are produced in huge quantities by Canada's mined oil sands industry. Due to the high colloidal stability of the contained fine solids, settling of fluid fine tailings can take hundreds of years, making the entrapped water unavailable and posing challenges to public health and the environment. This study focuses on developing value-added aggregation agents from specified risk materials (SRM), a waste protein stream from slaughterhouse industries, to achieve an improved separation of fluid fine tailings into free water and solids. Settling results using synthetic kaolinite slurries demonstrated that, though not as effective as hydrolyzed polyacrylamide, a commercial flocculant, the use of SRM-derived peptides enabled a 2-3-fold faster initial settling rate than the blank control. The pH of synthetic kaolinite tailings was observed to be slightly reduced with increasing peptides dosage in the test range (10-50 kg/ton). The experiments on diluted fluid fine tailings (as a representation of real oil sands tailings) demonstrated an optimum peptides dosage of 14 kg/ton, which resulted in a 4-fold faster initial settling rate compared to the untreated tailings. Overall, this study demonstrates the novelty and feasibility of using SRM-peptides to address intractable oil sands fluid tailings.

3D-printed, patient-specific DIEP flap templates for preoperative planning in breast reconstruction: a prospective case series.

BACKGROUND: Modern imaging technologies, such as computed tomographic angiography (CTA), can be useful for preoperative assessment in deep inferior epigastric artery perforator (DIEP) flap surgery. Planning perforator flap design can lead to improved surgical efficiency. However, current imaging modalities are limited by being displayed on a two-dimensional (2D) surface. In contrast, a 3D-printed model provides tactile feedback that facilitates superior understanding. Hence, we have 3D-printed patient-specific deep inferior epigastric artery perforator (DIEP) templates, in an affordable and convenient manner, for preoperative planning. METHODS: Twenty consecutive patients undergoing 25 immediate or delayed post-mastectomy autologous breast reconstruction with DIEP or muscle-sparing transverse rectus abdominis (MS-TRAM) flaps are recruited prospectively. Using free, open-source softwares (3D Slicer, Autodesk MeshMixer, and Cura) and desktop 3D printers (Ultimaker 3E and Moment), we created a template based on a patient's abdominal wall anatomy from CTA, with holes and lines indicating the position of perforators, their intramuscular course and the DIEA pedicle. RESULTS: The mean age of patients was 52 [38-67]. There were 15 immediate and 10 delayed reconstructions. 3D printing time took mean 18 hours and 123.7 g of plastic filament, which calculates to a mean material cost of AUD 8.25. DIEP templates accurately identified the perforators and reduced intraoperative perforator identification by 7.29 minutes (P=0.02). However, the intramuscular dissection time was not affected (P=0.34). Surgeons found the template useful for preoperative marking (8.6/10) and planning (7.9/10), but not for intramuscular dissection (5.9/10). There were no immediate flap-related complications. CONCLUSIONS: Our 3D-printed, patient-specific DIEP template is accurate, significantly reduces intraoperative perforator identification time and, hence, may be a useful tool for preoperative planning in autologous breast reconstruction.

The accuracy of clinical 3D printing in reconstructive surgery: literature review and in vivo validation study.

A growing number of studies demonstrate the benefits of 3D printing in improving surgical efficiency and subsequently clinical outcomes. However, the number of studies evaluating the accuracy of 3D printing techniques remains scarce. All publications appraising the accuracy of 3D printing between 1950 and 2018 were reviewed using well-established databases, including PubMed, Medline, Web of Science and Embase. An in vivo validation study of our 3D printing technique was undertaken using unprocessed chicken radius bones (Gallus gallus domesticus). Calculating its maximum length, we compared the measurements from computed tomography (CT) scans (CT group), image segmentation (SEG group) and 3D-printed (3DP) models (3DP group). Twenty-eight comparison studies in 19 papers have been identified. Published mean error of CT-based 3D printing techniques were 0.46 mm (1.06%) in stereolithography, 1.05 mm (1.78%) in binder jet technology, 0.72 mm (0.82%) in PolyJet technique, 0.20 mm (0.95%) in fused filament fabrication (FFF) and 0.72 mm (1.25%) in selective laser sintering (SLS). In the current in vivo validation study, mean errors were 0.34 mm (0.86%) in CT group, 1.02 mm (2.51%) in SEG group and 1.16 mm (2.84%) in 3DP group. Our Peninsula 3D printing technique using a FFF 3D printer thus produced accuracy similar to the published studies (1.16 mm, 2.84%). There was a statistically significant difference (P<10-4) between the CT group and the latter SEG and 3DP groups indicating that most of the error is introduced during image segmentation stage.

A Biorefinery Strategy That Introduces Hydrothermal Treatment Prior to Acid Hydrolysis for Co-generation of Furfural and Cellulose Nanocrystals.

Hydrothermal treatment of wood pulp at 150-225°C prior to acid hydrolysis was investigated in the context of isolating cellulose nanocrystals (CNCs). The objective was 2-folds as follows: (a) generating furfural as a value-added co-product; and (b) concentrating and forming new CNC precursors through thermal re-orientation of para-crystalline cellulose chains that will in turn improve CNC recovery and yield. Furfural yields up to 19 and 21% xylan conversion were obtained at 200 and 225°C hydrothermal treatments, respectively. In addition, these hydrothermal treatment conditions increased the crystallinity index of the pulp (77%) to 84 and 80%, respectively. Consequently, the CNC yield from hydrothermally treated wood pulp, when compared to untreated wood pulp, improved by up to 4- and 2-folds, respectively. An efficient acid hydrolysis process with yield improvements can translate to reduced CNC isolation and purification costs and increased production capacity. The qualities of the CNCs in terms of particle size and crystallinity were not affected due to hydrothermal treatment. However, the zeta potential, sulfur, hydrogen, and oxygen content of the CNCs were significantly lower at 225°C while carbon composition increased, and dark brown coloration was observed that indicates caramelization. This study demonstrates for the first time a novel biorefinery strategy that introduces hydrothermal treatment prior to acid hydrolysis to co-generate furfural and CNC with improved efficiency.

Improved bioethanol productivity through gas flow rate-driven self-cycling fermentation.

BACKGROUND: The growth of the cellulosic ethanol industry is currently impeded by high production costs. One possible solution is to improve the performance of fermentation itself, which has great potential to improve the economics of the entire production process. Here, we demonstrated significantly improved productivity through application of an advanced fermentation approach, named self-cycling fermentation (SCF), for cellulosic ethanol production. RESULTS: The flow rate of outlet gas from the fermenter was used as a real-time monitoring parameter to drive the cycling of the ethanol fermentation process. Then, long-term operation of SCF under anaerobic conditions was improved by the addition of ergosterol and fatty acids, which stabilized operation and reduced fermentation time. Finally, an automated SCF system was successfully operated for 21 cycles, with robust behavior and stable ethanol production. SCF maintained similar ethanol titers to batch operation while significantly reducing fermentation and down times. This led to significant improvements in ethanol volumetric productivity (the amount of ethanol produced by a cycle per working volume per cycle time)-ranging from 37.5 to 75.3%, depending on the cycle number, and in annual ethanol productivity (the amount of ethanol that can be produced each year at large scale)-reaching 75.8 ± 2.9%. Improved flocculation, with potential advantages for biomass removal and reduction in downstream costs, was also observed. CONCLUSION: Our successful demonstration of SCF could help reduce production costs for the cellulosic ethanol industry through improved productivity and automated operation.

The potential of fiber-depleted starch concentrate produced through air currents assisted particle separation of barley flour in bio-ethanol production.

Isolation of fiber concentrate enriched in ß-glucan from barley flour via air currents assisted particle separation (ACAPS) generates an underutilized by-product stream, starch concentrate. Since barley starch concentrate (BSC) is depleted in soluble fibre, we examined the enzyme requirements for its hydrolysis and subsequent fermentation. Lower doses of a common raw starch hydrolyzing enzyme (STARGEN™ 002) effectively hydrolyzed BSC, achieving similar hydrolysis kinetics to the wheat benchmark. Hydrolysis of BSC did not require further enzyme supplementation, which is required for optimal wheat hydrolysis. This likely resulted from the smaller particle size of BSC relative to wheat feedstocks. Interestingly, simultaneous saccharification and fermentation of BSC using a 0.25X dose of STARGEN™ 002 alone enabled efficient ethanol production, though a requirement for phosphorus supplementation was identified. This study proposes a biorefining strategy that supports the generation of a value-added co-product, starch concentrate, while significantly reducing the enzyme requirements for bioethanol production.