Simultaneous Saccharification Research Articles

Development of a starch-fermenting Zymomonas mobilis strain for bioethanol production

BackgroundBiorefinery using microorganisms to produce biofuels and value-added biochemicals derived from renewable biomass offers a promising alternative to meet our sustainable energy and environmental goals. The ethanologenic strain Zymomonas mobilis is considered as an excellent chassis for constructing microbial cell factories for diverse biochemicals due to its outstanding industrial characteristics in ethanol production, high specific productivity, and Generally Recognized as Safe (GRAS) status. Nonetheless, the restricted substrate range constrains its application.ResultsThe truncated ice nucleation protein InaK from Pseudomonas syringae was used as an autotransporter passenger, and α-amylase was fused to the C- terminal of InaK to equip the ethanol-producing bacterium with the capability to ferment renewable biomass. Western blot and flow cytometry analysis confirmed that the amylase was situated on the outer membrane. Whole-cell activity assays demonstrated that the amylase maintained its activity on the cell surface. The recombinant Z. mobilis facilitated the hydrolysis of starch into oligosaccharides and enabled the streamlining of simultaneous saccharification and fermentation (SSF) processes. In a 5% starch medium under SSF, recombinant strains containing Peno reached a maximum titer of 13.61 ± 0.12 g/L within 48 h. This represents an increase of 111.0% compared to the control strain's titer of titer of 6.45 ± 0.25 g/L.ConclusionsBy fusing the truncated ice nucleation protein InaK with α-amylase, we achieved efficient expression and surface display of the enzyme on Z. mobilis. This fusion protein exhibited remarkable enzymatic activity. Its presence enabled a cost-effective bioproduction process using starch as the sole carbon source, and it significantly reduced the required cycle time for SSF. This study not only provides an excellent Z. mobilis chassis for sustainable bioproduction from starch but also highlights the potential of Z. mobilis to function as an effective cellular factory for producing high-value products from renewable biomass.

Simultaneous saccharification and fermentation for d-lactic acid production using a metabolically engineered Escherichia coli adapted to high temperature

BackgroundEscherichia coli JU15 is a metabolically engineered strain capable to metabolize C5 and C6 sugars with a high yield of d-lactic acid production at its optimal growth temperature (37 °C). The simultaneous saccharification and fermentation process allow to use lignocellulosic biomass as a cost-effective and high-yield strategy. However, this process requires microorganisms capable of growth at a temperature close to 50 °C, at which the activity of cellulolytic enzymes works efficiently.ResultsThe thermotolerant strain GT48 was generated by adaptive laboratory evolution in batch and chemostat cultures under temperature increments until 48 °C. The strain GT48 was able to grow and ferment glucose to d-lactate at 47 °C. It was found that a pH of 6.3 conciliated with GT48 growth and cellulase activity of a commercial cocktail. Hence, this pH was used for the SSF of a diluted acid-pretreated corn stover (DAPCS) at a solid load of 15% (w/w), 15 FPU/g-DAPCS, and 47 °C. Under such conditions, the strain GT48 exhibited remarkable performance, producing d-lactate at a level of 1.41, 1.42, and 1.48-fold higher in titer, productivity, and yield, respectively, compared to parental strain at 45 °C.ConclusionsIn general, our results show for the first time that a thermal-adapted strain of E. coli is capable of being used in the simultaneous saccharification and fermentation process without pre-saccharification stage at high temperatures.

Engineering thermotolerant Kluyveromyces marxianus strains for resveratrol production by simultaneous saccharification and fermentation of whole slurry corn cob

The microbial biosynthesis of the antioxidant compound resveratrol offers an eco-friendly and sustainable alternative to chemical synthesis or plant extraction. Here, we showed that Kluyveromyces marxianus strains produce p-coumaric acid, a key precursor of resveratrol, with higher titres achieved under increased agitation conditions. Through further strain engineering, resveratrol production was achieved using glucose, xylose, and/or ethanol as substrates. Xylose emerged as the most favourable carbon source for resveratrol production, with ethanol supplementation during xylose culture resulting in increased resveratrol titres by limiting the accumulation of the by-product xylitol. At 37 ◦C, resveratrol production from corn cob hydrolysate and whole slurry substantially increased the yield of resveratrol per sugar, reaching titres of up to 69.26 mg/L. This work shows, for the first time, resveratrol production by K. marxianus and from corn cob whole slurry, establishing foundations for the development of an integrated sustainable process for resveratrol production from lignocellulosic materials.

Microwave-Assisted Acid and Alkali Pretreatment of Napier Grass for Enhanced Biohydrogen Production and Integrated Biorefinery Potential

Napier grass, a promising lignocellulosic energy crop, presents a complex composition that limits its bioconversion into fermentable products. To address this challenge, we applied microwave (MW) pretreatment assisted by acid and alkali, using varying chemical concentrations (0.5–1% w/v) and pretreatment times (3–10 min). Acid-catalyzed MW pretreatment achieved a maximal hemicellulose removal of 69.8%, while alkali-catalyzed MW pretreatment resulted in significant lignin removal of 65.5%. Without chemical catalysis, the pretreated hydrolysate significantly increased hydrogen yield to 38.0 ± 2.9 mL H2/g volatile solid (VS), five times greater than that obtained from untreated biomass. Hydrogen yield was further enhanced when the MW-pretreated solid underwent simultaneous saccharification and fermentation. The highest hydrogen yield of 89.2 ± 7.2 mL H2/g VS was achieved from alkali-catalyzed MW pretreated solid (0.5% w/v NaOH, 5 min), with a chemical oxygen demand (COD) solubilization of 62.6%. Increasing the NaOH concentration to 1% (w/v) slightly decreased hydrogen yield but significantly increased COD solubilization to 85.8%. The high carbohydrate content facilitated rapid cellulase hydrolysis, producing and accumulating a high concentration of fermentable sugars. However, this accumulation subsequently led to a shift towards lactic acid formation. The improved hydrogen yield and increased COD solubilization, along with the shift towards lactic acid production, suggest the possibility of optimizing this process for simultaneous production of multiple valuable products in an integrated biorefinery approach, potentially enhancing the economic viability of biomass conversion.

Distinct effects of dilute acid prehydrolysate inhibitors on enzymatic hydrolysis and yeast fermentation.

The effects of dilute acid prehydrolysate from poplar were investigated and compared in the enzymatic hydrolysis, fermentation, and simultaneous saccharification fermentation (SSF) in this study. The improvement of enzymatic hydrolysis and fermentation with resin adsorption and surfactant addition has also been represented. A total of 16 phenolic alcohols, aldehydes, acids and 3 furan derivatives in the prehydrolysates were identified and quantified by gas chromatography/mass spectrometry (GC/MS). The degree of inhibition from the phenolic compounds (26.55%) in prehydrolysate on the enzymatic hydrolysis was much higher than carbohydrates-derived inhibitors (0.52-4.64%). Around 40% degree of inhibition was eliminated in Avicel enzymatic hydrolysis when 75% of prehydrolysates phenolic compounds were removed by resin adsorption. This showed distinguishing inhibition degrees of various prehydrolysate phenolic compounds. Inhibition of prehydrolysate on enzymatic hydrolysis was more dosage-dependent, while their suppression on the fermentation showed a more complicated mode: fermentation could be terminated by the untreated prehydrolysate, while a small number of prehydrolysate inhibitors even improved the glucose consumption and ethanol production in the fermentation. Correlated with this distinct inhibition modes of prehydrolysate, the improvement of Tween 80 addition in SSF was around 7.10% for the final ethanol yield when the glucose accumulation was promoted by 76.6%.

Enhanced bioethanol production from Compositae plant stalks: Integrating dry acid pretreatment and fungal mediated biodetoxification

Compositae is an important economic plant with relatively high contents of water-soluble sugars in stalk section. The pretreatment of Compositae plant stalks quickly converts the water-soluble sugars into high titers of furan aldehydes, which inhibits the viability of consequent fermentation strains. This study used the typical Compositae plant stalks of sunflower, Jerusalem artichoke, and stevia as feedstocks for dry acid pretreatment under high solids loading, then a unique solid-state biodetoxification method was applied to degrade these high-titer inhibitors. The results showed that temperature and sulfuric acid concentration were two key parameters for enhancing pretreatment efficiency. Enzymatic hydrolysis yield of the above pretreated stalks reached up to 79.68%, 66.75% and 74.05%, respectively. For pretreated Jerusalem artichoke stalk, it contained 37.36% of cellulose, 2.72% of xylan, 3.04% of glucose, 11.64% of xylose, 20.54% of lignin, and some inhibitors (3.80% of acetate, 0.24% of HMF and 0.23% of furfural). After biodetoxification, 100% of furfural, 40% of HMF, and 36% of acetate were quickly removed by Amorphotheca resinae ZN1, which resulted in 55.57 g/L ethanol production (equivalent to 7.1% by volumetric percentage) with the yield of 55.54% from 73.59 g/L of glucose and 40.69 g/L of xylose by simultaneous saccharification and co-fermentation (SSCF). This study provides a combinational approach of dry acid pretreatment and biodetoxification for Compositae plant stalks biorefinery.

Production and Characterization of Bioethanol Using Native Microbial Isolates from Decomposed Maize Cob via Simultaneous Saccharification and Fermentation

Maize cob a major component of agricultural waste composed mainly of cellulose that can be converted to bioethanol through fermentation as means of waste management. Achieving enhances bioethanol yield without ascertaining proper conversion pathway may be subjective. Therefore, this research aimed at converting maize cob to bioethanol through fermentation using natives microbial isolates from decomposed maize cob via Response Surface Methodology. Microbial strains used were Pichia kudriavzevii strains with accession number KP998095.1 and MN861069.1. A pH value of 5.5 corresponded to bioethanol yield of 52.45 g/L, pH was observed to be sensitive to fermentation hence influence the extent of fermentation process. Optical density (O. D610nm) of 2.2 after eight (8) days of fermentation corresponded to bioethanol yield of 52.45 g/L. The growth pattern observed in most of the samples followed a typical microbial growth pattern depicting lag, log and stationary phases. Reducing soluble sugar of 23.5 mg/L on enzyme hydrolysis corresponded to bioethanol yield of 52.45 g/L, reducing soluble sugar content of the experimental samples were observed to decrease as the fermentation progresses. The infrared spectra of the optimum sample distillate of bioethanol from the fermentation revealed the presence of OH at 3311.7 cm-1 stretching band and C = C at 1636.3 cm−1 stretching band. The elemental compositions of the distillate were oxygen (31.03%), hydrogen (9.74%), carbon (56.85%), nitrogen (1.92%) and sulphur (0.46%) which confirmed the presence of bioethanol. The empirical formula of the best distillate using C, H, and O compositions (%) was found to be C2H5OH, hence revealed the presence of bioethanol. The result of the GC-MS analysis showed that mass spectra comparison of the various peaks revealed the presence of bioethanol as the largest peak with 76.38% ethanol by concentration. Maize cob can be said to be a promising feedstock for bioethanol production using native microbial isolates.

Waste Bread as Raw Material for Ethanol Production: Effect of Mash Preparation Methods on Fermentation Efficiency

The issue of managing waste bread is a global concern, with significant environmental and the economic implications. The utilisation of waste bread for bioethanol production, employing energy-saving technology, could prevent these consequences and reduce the consumption of traditionally used fossil fuels. The objective of this study was to evaluate the influence of the type of waste bread (wheat and wheat–rye sourdough) and the mash preparation method on the results of alcoholic fermentation and the concentration of selected congeners in the distillates. The highest fermentation efficiency (96% of theoretical) was achieved for both types of bread through the utilisation of the pressureless starch liberation method combined with simultaneous saccharification and fermentation. The separate saccharification of starch resulted in lower process efficiencies (from 85.75 to 88.60% of theoretical). The application of the native starch hydrolysis method (without starch activation) for the fermentation of wheat bread-based mashes exhibited a higher efficiency (87.85% of the theoretical) than that observed for the wheat–rye bread-based mash sample (83.74% of theoretical). All of the obtained spirit distillates exhibited a low concentration of methanol (≤300 mg/L alcohol 100% v/v) and comply with the requirements of the EU regulation for ethyl alcohol of agricultural origin (rectified spirit).

Harnessing Bacillus subtilis QY5 PP784163 for Bioethanol Production from Potato Peel Waste and Nutrient Recovery for Animal Feed: Maximizing Resource Efficiency

The present work focuses on the utilization of potato peel waste for the production of bioethanol. In the present study, extensive screening was undertaken to isolate amylolytic and cellulolytic microbes using starchy biomass. After confirming the chemical composition of potato peel waste (PPW), several trials were performed to enhance the amylase and cellulase production from Bacillus subtilis to hydrolyze the PPW in submerged fermentation. Optimization of physical parameters was performed using both commercial and indigenous media from enzymatically hydrolyzed PPW. Different routes of various combinations were designed to enhance bioethanol production. The maximum ethanol titer of 0.50% and 0.41% was recorded in Route B and A, i.e., separate saccharification and ethanol fermentation and consolidated fermentation. Simultaneous saccharification and fermentation (SSF) also measured a good ethanol yield of 0.46%. The fermented residual cake was checked for nutritional components and showed a high content of protein and amino acids because of the addition of unicellular yeasts. This cake can be utilized as an animal feed supplement.

Stirring the hydrogen and butanol production from Enset fiber via simultaneous saccharification and fermentation (SSF) process

Enset fiber is a promising feedstock for biofuel production with the potential to reduce carbon emissions and improve the sustainability of the energy system. This study aimed to maximize hydrogen and butanol production from Enset fiber through simultaneous saccharification and fermentation (SSF) process in bottles as well as in bioreactor. The SSF process in bottles resulted in a higher butanol concentration of 11.36 g/L with a yield of 0.23 g/g and a productivity of 0.16 g/(L h) at the optimal process parameters of 5% (w/v) substrate loading, 16 FPU/g cellulase loading, and 100 rpm agitation speed from pretreated Enset fiber. Moreover, a comparable result to the bottle experiment was observed in the bioreactor with pH-uncontrolled SSF process, although with a decreased in butanol productivity to 0.095 g/(L h). However, using the pre-hydrolysis simultaneous saccharification and fermentation (PSSF) process in the bioreactor with a 7% (w/v) substrate loading led to the highest butanol concentration of 12.84 g/L with a productivity of 0.104 g/(L h). Furthermore, optimizing the SSF process parameters to favor hydrogen resulted in an increased hydrogen yield of 198.27 mL/g-Enset fiber at atmospheric pressure, an initial pH of 8.0, and 37 °C. In general, stirring the SSF process to shift the product ratio to either hydrogen or butanol was possible by adjusting temperature and pressure. At 37 °C and atmospheric pressure, the process resulted in an e-mol yield of 12% for hydrogen and 38% for butanol. Alternatively, at 30 °C and 0.55 bar overpressure, the process achieved a yield of 6% e-mol of hydrogen and 48% e-mol of butanol. This is the first study to produce hydrogen and butanol from Enset fiber using the SSF process and contributes to the development of a circular bioeconomy.Graphical

Altered sterol composition mediates multiple tolerance of Kluyveromyces marxianus for xylitol production

BackgroundCurrently, the synthesis of compounds based on microbial cell factories is rapidly advancing, yet it encounters several challenges. During the production process, engineered strains frequently encounter disturbances in the cultivation environment or the impact of their metabolites, such as high temperature, acid-base imbalances, hypertonicity, organic solvents, toxic byproducts, and mechanical damage. These stress factors can constrain the efficiency of microbial fermentation, resulting in slow cell growth, decreased production, significantly increased energy consumption, and other issues that severely limit the application of microbial cell factories.ResultsThis study demonstrated that sterol engineering in Kluyveromyces marxianus, achieved by overexpressing or deleting the coding genes for the last five steps of ergosterol synthase (Erg2-Erg6), altered the composition and ratio of sterols in its cell membrane, and affected its multiple tolerance. The results suggest that the knockout of the Erg5 can enhance the thermotolerance of K. marxianus, while the overexpression of the Erg4 can improve its acid tolerance. Additionally, engineering strain overexpressed Erg6 improved its tolerance to elevated temperature, hypertonic, and acid. YZB453, obtained by overexpressing Erg6 in an engineering strain with high efficiency in synthesizing xylitol, produced 101.22 g/L xylitol at 45oC and 75.11 g/L xylitol at 46oC. Using corncob hydrolysate for simultaneous saccharification and fermentation (SSF) at 46oC that xylose released from corncob hydrolysate by saccharification with hemicellulase, YZB453 can produce 45.98 g/L of xylitol, saving 53.72% of the cost of hemicellulase compared to 42oC.ConclusionsThis study elucidates the mechanism by which K. marxianus acquires resistance to various antifungal drugs, high temperatures, high osmolarity, acidity, and other stressors, through alterations in the composition and ratio of membrane sterols. By employing sterol engineering, the fermentation temperature of this unconventional thermotolerant K. marxianus was further elevated, ultimately providing an efficient platform for synthesizing high-value-added xylitol from biomass via the SSF process at temperatures exceeding 45 °C.

Life Cycle Assessment of Bioethanol Produced from Banana Peduncle

Abstract Biofuel production has been promoted in part to reduce dependency on fossil fuels in transportation due to fewer environmental emissions. Feedstocks for biofuels include agricultural waste and non-edible crops, suggesting that large amounts of waste can be used to produce biofuels such as bioethanol, which is currently being blended with gasoline in the Philippines as transportation fuel. However, shifting from non-renewable fuels to bioethanol and other biofuels as the dominant transportation fuel must consider aspects other than fuel usage. The objectives of this study are to perform cradle-to-grave life cycle analysis on bioethanol produced from banana peduncle and determine the contributions of each stage in the life cycle to different environmental impacts and compare the results with those of other transport fuels. The contributions of each stage in the life cycle of bioethanol are modelled in openLCA software with the ReCiPe impact assessment method. It was identified that electricity use in simultaneous saccharification and fermentation, and sulfuric acid consumption are the main contributors to the different environmental impacts. Comparison of the results of banana peduncle bioethanol production stage to those of the first-generation bioethanol production showed that most of the emissions were lower except for those pertaining to freshwater ecotoxicity, human toxicity, marine ecotoxicity, and metal depletion. Comparing fuel use, environmental impacts of conventional gasoline were slightly lower than those of a 10% mix with bioethanol. But impacts of the 85% mix with bioethanol in climate change and marine eutrophication are higher by 29% and 37%, respectively, than those of conventional gasoline. Overall, increasing the ethanol concentration would reduce the emissions during fuel usage but impacts of production will increase. Potential process improvements for environmental performance of bioethanol from banana peduncle are in the pre-treatment methods and fermentation set-up in bioethanol production, use of renewable power, and ethanol blending concentrations with gasoline.

Streamlined fractionation for recovery of high-yield xylo-oligosaccharides, pure lignin and ethanol from poplar using short-chain organic acid/pentanol biphasic system

Biphasic pretreatment offers a sustainable method by integrating the fractionation of hemicellulose, lignin, and cellulose into a single process, thereby enhancing biomass resource utilization while reducing environmental impact. However, this process faces the challenge of diverse hemicellulose products with low added value. This study employed organic acid-catalyzed water/pentanol biphasic pretreatment to selectively convert hemicellulose into xylooligosaccharides (XOS), while simultaneously separating lignin and cellulose. Both the organic acids and pentanol used are biodegradable and compatible. The lactic acid (LA)/pentanol biphasic system was particularly effective for XOS production and lignin removal, attributed to the high acidity of LA and its relatively low partition coefficients in the water/pentanol system, crucial factors influencing hemicellulose and lignin separation efficiency. The XOS yields reached 46.9 %, while the lignin removal rate was 74.6 %. Additionally, LA/pentanol pretreatment significantly enhanced cellulose digestibility, demonstrated by an ethanol production of 54.1 g/L during simultaneous saccharification fermentation at 15 % solids loading. The recovered lignin from the organic phase retained the structural characteristics of native lignin. It also had a low molecular weight and abundant phenolic hydroxyl groups, indicating its suitability for further valorization. Pentanol maintained its performance after four cycles of reuse, demonstrating the stability and reusability of the solvent system. This study highlighted the potential of the LA/pentanol biphasic system for simultaneous hemicellulose conversion and lignin isolation, offering a simplified and sustainable one-step valorization route for biomass.

Integrating use of sugarcane bagasse with sugarcane juice for efficient l-lactic acid production through fed-batch simultaneous saccharification and fermentation: Process configurations and kinetic analysis

The present study investigated the utilization of sugarcane juice (SJ) and sugarcane bagasse (SB) for L-lactic acid (L-LA) production by a newly isolated Enterococcus gallinarum TSKKU D-6. SJ was first investigated as a single substrate, yielding 43.9 ± 2.9 g-LA/L, with a fermentation efficiency of 72.0 ± 0.1 %, based on sucrose content in SJ. On the other hand, simultaneous saccharification and fermentation (SSF) of SB as a single substrate yielded 68.2 ± 2.7 g-LA/L, with a fermentation efficiency of 74.1 ± 0.0 %, based on cellulose content in SB. SSF of SJ and SB as co-substrates was subsequently carried out to increase the acid production, where SJ was first fermented, followed by the addition of SB to enhance LA titer. Effects of mixing and SB addition strategy on the kinetics and economic feasibility of L-LA production were investigated using a bioreactor equipped with a single and dual impellers, as well as the use of dual impellers under fed-batch SSF. The use of single and dual impellers gave similar L-LA titers of 95.9 ± 1.4 and 102.6 ± 0.6 g/L, respectively. Nevertheless, the use of dual impellers shortened the processing time, enhancing LA productivity from 0.37 to 1.12 g/(L·h). As a result, the economic yield and productivity were improved by 7.1 % and 187.5 %, respectively. Better still, performing fed-batch SSF with the use of dual impellers further improved the economic productivity by 8.7 %. This study demonstrated that integrating use of SB as a low-cost substrate considerably enhanced the acid production and lessened the use of SJ. It was also demonstrated that mixing, and process configuration are critical factors determining the process performance.

Investigation of the effect of specific gravity and pH on the fermentation period of a single and combined algae species as a potential bioethanol feedstock

Algae has garnered significant attention as a promising biomass source for bioethanol production and as a solution to sustainability issues. Nevertheless, the disruption of complex carbohydrates required for yeast fermentation occurs during algae cultivation. The fermentation process, which is critical for producing bioethanol as a cost-effective and environmentally friendly alternative fuel, may be improved by meticulously managing the parameters that influence fermentation, such as specific gravity and pH. Bioethanol was produced from algae species (Navicula sp., Oscillatoria sp. and diatoms) using simultaneous saccharification and fermentation (SSF) processes. A control, single and combined algal species were prepared in the following formation: Oscillatoria sp. and Navicula sp. (sample A), Oscillatoria sp. (sample B), diatom and Oscillatoria sp. (sample C), Navicula sp. (sample D), and diatoms, Navicula sp. and Oscillatoria sp (sample E). The daily bioethanol concentrations in the fermentation medium were measured using a digital optical refractometer, and a Two-way ANOVA analysis (p < 0.05) was conducted to determine the differences between the period of fermentation and the bioethanol concentration. Additionally, the pH and specific gravity were assessed. The Two-way ANOVA analysis conducted indicated that the F-values surpassed the F-critical values and the p-values were all notably below 0.05, suggesting a statistically significant distinction between the samples in their fermentation periods and bioethanol concentration. The highest concentration was observed in sample E at 39.53 g/L, followed by samples C and D at 37.36 g/L, samples A and B at 35.10 g/L, and the control at 4.78 g/L. The findings showed that mixed cultures could potentially improve ethanol yield. The optimal fermentation period was determined to be 72 h. The pH levels in the control and algae samples varied between 6.5 and 6.7 and 7.06 to 8.42, respectively. The specific gravity in the control and algae samples ranged from 1.003 to 1.004 and 1.023 to 1.037, respectively. During algae fermentation, specific gravity initially increased, then stabilized before decreasing. pH levels correlated with fermentation duration. Understanding these factors is crucial for maximizing bioethanol production. This discovery could lead to exploring how different algae species interact to improve cultivation methods.

Biovalorizing felled oil palm trunk as a sole feedstock for lactic acid production through efficient simultaneous saccharification and fermentation

This study aimed to develop practical biorefinery process for bio-valorizing felled oil palm trunk (OPT) as a sole feedstock for lactic acid (LA) production. OPT was separated into oil palm sap (OPS), vascular bundle (OPT-VB), and parenchyma (OPT-PA) fractions. OPS containing high amounts of sugars (38.69 g/L) and nitrogen (0.63 g/L), could be used directly for LA production by Lactobacillus acidophilus and also as base medium for simultaneous saccharification and fermentation (SSF) of OTP-VB and OPT-PA. The repeated SSF efficiently utilized cellulosic OPT-VB and produced LA up to 50–71 g/L during five cycles. Due to high water-absorbing and swelling properties of OPT-PA, it could not be initially added at high loadings. It was then intermittently added through fed-batch SSF, which effectively produced LA of 72.85 ± 1.61 g/L. These strategies have shown the efficient biorefinery process for biovalorization of OPT and may also be applicable to other similar agricultural wastes.

Cellulosic Ethanol Production from High-Solids Corncob Residues by Simultaneous Saccharification and Fermentation on a Pilot Scale

Cellulosic Ethanol Production from High-Solids Corncob Residues by Simultaneous Saccharification and Fermentation on a Pilot Scale

High-efficiency conversion of corn bran to ethanol at 150 L scale

Fractionated corn bran was processed to maximize ethanol production from starch, cellulose, and xylan. After various bench-scale experiments, an optimized process with dilute acid pretreatment (1.5 % w/w H2SO4) at 90 °C for 60 min was utilized followed by enzymatic hydrolysis using cellulase and hemicellulase for 48 hr. After simultaneous saccharification (regarding starch) and fermentation at 150 L using an engineered yeast, which consumes both glucose and xylose to make ethanol, the 86 % total sugar conversion yield was achieved, including conversions of 95 % for starch, 77 % for cellulose and 77 % for xylan. Also, an accurate mass balance was formulated for ethanol-producing carbohydrates including starch, cellulose, and xylan from feedstock to final ethanol. A highly efficient process of converting corn fiber to ethanol was successfully scaled up to 150 L.

Bioethanol derived from rice straw agricultural waste as alternative energy towards a pollution-free era

Abstract Rice production occupies the first position as raw material for bioethanol production, with a total output throughout Indonesia of 56.63 million tons in 2023 (BPS, 2023). The purpose of this innovation is to create bioethanol derived from new raw materials, namely rice straw, by applying the simultaneous saccharification and fermentation (SSF) method for the conversion of lignocellulose into alcohol, which will produce bioethanol with a purity level of about 99% with a more efficient process. This method goes through several processes, including breaking the size of the rice straw to 0.1 mm and mixing it with several bacteria for fermentation and hydrolysis. The saccharification process is also carried out until the distillation process to make high levels of bioethanol. Bioethanol from the simultaneous saccharification and fermentation (SSF) method is tested using an Octane Number Analyzer to determine the octane number content. The test included mixing bioethanol with Pertamax 92 to prove the effect of adding bioethanol to Pertamax, and the result was 93.1. Therefore, the innovation of making bioethanol from rice straw with the SSF method is expected to be a solution for Indonesia towards a pollution-free era.

The Effect of Technological Conditions on ABE Fermentation and Butanol Production of Rye Straw and the Composition of Volatile Compounds.

The objective of this study was to evaluate the effect of pretreatment and different technological conditions on the course of ABE fermentation of rye straw (RS) and the composition of volatile compounds in the distillates obtained. The highest concentration of ABE and butanol was obtained from the fermentation of pretreated rye straw by alkaline hydrolysis followed by detoxification and enzymatic hydrolysis. After 72 h of fermentation, the maximum butanol concentration, productivity, and yield from RS were 16.11 g/L, 0.224 g/L/h, and 0.402 g/g, respectively. Three different methods to produce butanol were tested: the two-step process (SHF), the simultaneous process (SSF), and simultaneous saccharification with ABE fermentation (consolidation SHF/SSF). The SHF/SSF process observed that ABE concentration (21.28 g/L) was higher than in the SSF (20.03 g/L) and lower compared with the SHF (22.21 g/L). The effect of the detoxification process and various ABE fermentation technologies on the composition of volatile compounds formed during fermentation and distillation were analyzed.