Enzyme Dosage Research Articles

Food industry biowaste as substrate for biosolvents production focusing on lactic acid and ethyl lactate

Solvents represent a major category of chemicals due to their necessity in a variety of industries. The majority of solvents derived from fossil carbon are hazardous to both human health and the environment. In this context, it seems imperative to convert biomass into new alternative greener solvents. The present study concentrates on the production of two biosolvents; namely lactic acid and ethyl lactate, from biowaste of baby food industry. For the production of lactic acid parameters as the dosages of enzymes (5 mg/gLactose and 20 mg/gLactose) and inoculum size (5% v/v and 10% v/v) were examined. The lactic acid concentration reached almost 17.3g/L after 144 hours with 5mgLactozymePure/glactose and 10%v/v inoculum size. Repeated fermentation was also applied yielding a lactic acid productivity of 0.97 g/L h, which is 8 times higher than the conventional batch fermentation. Moreover, the production of ethyl lactate from bioethanol and lactic acid from the fermentation broth was examined. Lactic acid conversion yields as high as 59.9% at 255min were observed. Overall, the results of this work are very promising but further research is needed to optimize conditions and evaluate scalability of the production of these biosolvents from biowaste, since the production of lactic acid and ethyl-lactate from biowaste provides a sustainable approach to the circular economy, limiting waste and minimizing the environmental effect of industrial processes.

Patterns, Prognostic Implications, and Rural-Urban Disparities in Optimal GDMT Following HFrEF Diagnosis Among Medicare Beneficiaries

BackgroundPatterns and disparities in guideline-directed medical therapy (GDMT) uptake for heart failure with reduced ejection fraction (HFrEF) across rural vs urban regions are not well described. ObjectivesThis study aims to evaluate patterns, prognostic implications, and rural-urban differences in GDMT use among Medicare beneficiaries following new-onset HFrEF. MethodsPatients with a diagnosis of new-onset HFrEF in a 5% Medicare sample with available data for Part D medication use were identified from January 2015 through December 2020. The primary exposure was residence in rural vs urban zip codes. Optimal triple GDMT was defined as ≥50% of the target daily dose of beta-blockers, ≥50% of the target daily dose of angiotensin-converting enzyme inhibitors/angiotensin receptor blocker or any dose of sacubitril/valsartan, and any dose of mineralocorticoid receptor antagonist. The association between the achievement of optimal GDMT over time following new-onset HFrEF diagnosis and risk of all-cause mortality and subsequent HF hospitalization was also evaluated using adjusted Cox models. The association between living in rural vs urban location and time to optimal GDMT achievement over a 12-month follow-up was assessed using cumulative incidence curves and adjusted Fine-Gray subdistribution hazard models. ResultsA total of 41,296 patients (age: 76.7 years; 15.0% Black; 27.6% rural) were included. Optimal GDMT use over the 12-month follow-up was low, with 22.5% initiated on any dose of triple GDMT and 9.1% on optimal GDMT doses. Optimal GDMT on follow-up was significantly associated with a lower risk of death (HR: 0.89 [95% CI: 0.85-0.94]; P < 0.001) and subsequent HF hospitalization (HR: 0.93 [95% CI: 0.87-0.98]; P = 0.02). Optimal GDMT use at 12 months was significantly lower among patients living in rural (vs urban) areas (8.4% vs 9.3%; P = 0.02). In adjusted analysis, living in rural (vs urban) locations was associated with a significantly lower probability of achieving optimal GDMT (HR: 0.92 [95% CI: 0.86-0.98]; P = 0.01 Differences in optimal GDMT use following HFrEF diagnosis accounted for 16% of excess mortality risk among patients living in rural (vs urban) areas. ConclusionsUse of optimal GDMT following new-onset HFrEF diagnosis is low, with substantially lower use noted among patients living in rural vs urban locations. Suboptimal GDMT use following new-onset HFrEF was associated with an increased risk of mortality and subsequent HF hospitalization.

Juice yield and pectin indicators in apple and carrot pomace

Background: Pectin exhibits different properties based on its degree of esterification, forming gels and serving as a structure-forming agent in food products, or forming complexes with heavy metal ions, finding applications in the development of therapeutic products for the elimination of heavy metal ions from the human body. Context and purpose of this study: The purpose of this study is to investigate the influence of enzymatic treatment on the yield and quality of apple and carrot juices, as well as the quality parameters of pectin in pomace. Our objectives were to select an enzymatic preparation for processing apple and carrot pomace and to study changes in the properties of pectins present in the pomace depending on the dosage of the enzyme preparation.Results: The results of our experiments revealed that for apple pomace processing, it is more beneficial to use the enzyme preparation Vegazym M with a dosage of 0.09% of the pomace mass, while for carrot pomace processing, the enzyme preparation Fructozym MA with a dosage of 0.07% of the pomace mass proved to be the most suitable. These enzyme preparations in the specified amounts ensure maximum juice yield. It has been established that changing the dose of enzymes changes the complexing properties of pectin, which allows its use in food products with therapeutic and prophylactic properties.Conclusions: The enzyme preparations allow for specific modifications, such as pectin modification in this case, enabling the versatile use of pectin as either a structure-forming agent or for the development of therapeutic and preventive food products.Keywords:Apple and carrot juices, enzyme preparations, apple and carrot pomace, pectin, soluble and insoluble pectin, degree of esterification and pectin complexation, functional products.

Protein production from cellulosic waste using candida utilis

With rapid population growth there is a lot of interest in developing alternative protein sources, like protein yeast cultures. For growth of yeast could be used agricultural and food processing waste, but such source of hydrocarbons need to be pretreated. The purpose of the presented study is to assess the effect of steam explosion treatment on the process of feed protein production, including the influence on the enzymatic hydrolysis, cultivation of yeast and resulting products characteristics. Wheat straw, spelt hull and sunflower husk were subjected to steam explosive activation at 165 °C and 210 °C. The products were subjected to enzymatic hydrolysis at the following conditions: enzyme dose 12 g/kg of raw material and temperature of 45 °C. Total reducing sugars content and component composition were evaluated in the hydrolysates using IR spectrometry and HPLC respectively. A pure yeast culture of Candida utilis, was grown on hydrolysates (2 g/L) in a 10 L bioreactor unit at 35 °C for 24 h. The samples of protein were evaluated for crude protein, true protein, fiber, fat and ash content. Conversion efficiency was calculated. The highest conversion efficiency was observed for spelt husks activated at 165 °C: reducing sugars yield was 56.2 % out of 73.3 % of theoretical yield; biomass concentration reaches 52.9 g/L, with reducing sugar conversion of 80.1 %. The crude protein content of yeast was 53.9 % (42 % according to Barnstein). Hydrolysates from activated materials, give a higher yeast biomass yield of 21–42 % compared to hydrolysates of non-activated raw materials.

Bayesian-optimized random forest prediction of key properties of micro-/nanofibrillated cellulose from different woody and non-woody feedstocks

The scale-up of nanocellulose production, a still challenging task, could benefit greatly from machine learning. In this paper, random forest regressors were applied to predict two important parameters for nanocellulose processing: nanofibrillation yield and aspect ratio. The dataset comprised diverse pulp sources, ranging from non-woody and woody feedstock, and two different types of pulp pre-treatments, namely mechanical refining and enzymatic hydrolysis. The obtained models were evaluated in terms of number of features and optimized with regard to some important hyperparameters, using the Bayesian optimization function from the SkOpt library. Considering the heterogeneity of the data, the prediction of both aspect ratio and yield of nanofibrillation was deemed satisfactory. For the former, R² scores of 0.986, 0.902 and 0.932 were obtained for the training, validation and testing subsets, respectively. Regarding the latter, R² scores of 0.994, 0.947 and 0.877 were achieved for the same types of subsets. Other important remarks are that enzyme dosage was the most important feature for predicting aspect ratio, while it did not play an important role for yield modelling. For this output, the transmittance at 600 nm accounted for almost 90% of the total feature importance.

Cellulase immobilization on zeolitic imidazolate frameworks for boosting cellulose hydrolysis at high solids loading

This study investigates the cellulase immobilization onto zeolitic imidazolate frameworks (ZIFs) to enable efficient cellulose hydrolysis at high solids loading. Different ZIF carriers (ZIF-8, ZIF-8-NH2, Fe3O4@ZIF-8, and Fe3O4@ZIF-8-NH2) were prepared and characterized. The resulting ZIF-immobilized cellulases were subsequently analyzed for their loading capacity and enzyme activity, as well as their biochemical properties such as temperature stability, pH stability, storage stability, enzyme leaching, and enzyme kinetics. Results revealed that the cellulase immobilized on Fe3O4@ZIF-8-NH2 exhibited an exceptional loading capacity of 359.89 mg/g and a relative enzyme activity of 69.39%. Remarkably, at a solid loading of 15% (w/w) and an enzyme dosage of 5 FPU/g cellulose, the Fe3O4@ZIF-8-NH2 immobilized cellulase demonstrated a 20.44% higher hydrolysis yield compared to the free cellulase. Furthermore, this immobilized enzyme system displayed robust reusability, retaining 71.03% of its initial activity even after 10 cycles of reuse. A proposed mechanism of enhanced enzymatic hydrolysis by ZIF-immobilized cellulases was also presented. These findings have significant implications for the future application of ZIF-immobilized cellulases in efficient and cost-effective lignocellulosic bioconversion.

Process optimization for saccharification and fermentation of the Organic Fraction of Municipal Solid Waste (OFMSW) to maximize ethanol production performance

The Organic Fraction of Municipal Solid Waste (OFMSW) contains paper and cardboard, an attractive cellulosic feedstock for bioethanol production. Waste paper/cardboard (WPC) was subjected to mild acid treatment in solids loadings from 20 to 27.5 %. Different doses of commercial enzyme cocktail and various adjuvants facilitating enzymatic saccharification were tested. Enzyme dosing of 3.75 FPU/g fiber with very slow fed-batch saccharification of 27.5 % (w/v) solids from model lignin-free paper pulp resulted in 12.6 % (w/v) total sugar after 74 h. Use of cheap non-catalytic waste protein adjuvants including Soymeal, Protisyr, Feather meal strongly improved enzymatic saccharification and reduced the overall process cost by reducing commercial enzyme dosing. After fermentation with the industrial yeast strain BMD44 (Cellusec® 1.0) an ethanol titer of 5.77 % (v/v) was obtained using a reduced enzyme loading of 2.5 FPU/g of actual industrial WPC fiber. These results show the potential of economically profitable second-generation bioethanol production with WPC fiber.

PSIV-20 An in Vitro Digestion Procedure Using Daisyii Incubator Can Replace Conventional in Vitro Digestion Procedures Using Flasks for Estimating Ileal Digestibility of Feed Ingredients for Pigs

Abstract In vitro procedures using flasks have been used for simulating nutrient utilization by pigs. However, these procedures are time-consuming and laborious and require a number of flasks and filter crucibles. The objective of this study was to develop an in vitro procedure using DaisyII incubator for simultaneous analysis of multiple samples. In a conventional in vitro procedure, 10 mg of pepsin in step 1 and 50 mg of pancreatin in step 2 are used for each flask containing 1 g of feed sample. In a preliminary experiment, 24 samples each in R55 bags were digested in a jar of DaisyII incubator with 24 times the quantity of buffer solution and enzymes of the conventional flask procedure. In the preliminary experiment, greater crude protein (CP) digestibility values were observed in the DaisyII incubator procedure compared with the conventional flask procedure. To determine optimum enzyme doses in the in vitro ileal disappearance (IVIDDaisy) procedure using the DaisyII incubator, 3 doses of pepsin (10, 7.5, and 5 mg/sample in step 1) and 3 doses of pancreatin (50, 37.5, and 25 mg/sample in step 2) were tested in a 3 × 3 factorial arrangement for 11 test ingredients. The quantity of buffer solution and enzymes in a jar was increased proportionally with the number of samples. The 11 test ingredients were barley, copra meal, corn, corn distillers dried grains with solubles, corn gluten feed, corn gluten meal, palm kernel meal, rice bran, soybean hulls, soybean meal, and wheat bran. The in vitro ileal disappearance (IVIDflask) of CP in the 11 ingredients was determined using the conventional flask procedure. The sum of square of deviation between IVIDflask of CP and IVIDDaisy of CP was the least when 5 mg pepsin/sample in step 1 and 37.5 mg/sample in step 2 were used (IVIDflask of CP, % = 14.4 + 0.81 × IVIDDaisy of CP, %; r2 = 0.748). On the other hand, the determination coefficient was the greatest when 10 mg pepsin/sample in step 1 and 50 mg/sample in step 2 were used (IVIDflask of CP, % = 2.5 + 0.93 × IVIDDaisy of CP, %; r2 = 0.878). In conclusion, the in vitro procedure using a DaisyII incubator can be used for estimating ileal digestibility of protein in multiple samples simultaneously for pigs.

LPMO-supported saccharification of biomass: effects of continuous aeration of reaction mixtures with variable fractions of water-insoluble solids and cellulolytic enzymes

BackgroundHigh substrate concentrations and high sugar yields are important aspects of enzymatic saccharification of lignocellulosic substrates. The benefit of supporting the catalytic action of lytic polysaccharide monooxygenase (LPMO) through continuous aeration of slurries of pretreated softwood was weighed against problems associated with increasing substrate content (quantitated as WIS, water-insoluble solids, in the range 12.5–17.5%), and was compared to the beneficial effect on the saccharification reaction achieved by increasing the enzyme preparation (Cellic CTec3) loadings. Aerated reactions were compared to reactions supplied with N2 to assess the contribution of LPMO to the saccharification reactions. Analysis using 13C NMR spectroscopy, XRD, Simons’ staining, BET analysis, and SEM analysis was used to gain further insights into the effects of the cellulolytic enzymes on the substrate under different reaction conditions.ResultsAlthough glucose production after 72 h was higher at 17.5% WIS than at 12.5% WIS, glucan conversion decreased with 24% (air) and 17% (N2). Compared to reactions with N2, the average increases in glucose production for aerated reactions were 91% (12.5% WIS), 70% (15.0% WIS), and 67% (17.5% WIS). Improvements in glucan conversion through aeration were larger (55–86%) than the negative effects of increasing WIS content. For reactions with 12.5% WIS, increased enzyme dosage with 50% improved glucan conversion with 25–30% for air and N2, whereas improvements with double enzyme dosage were 30% (N2) and 39% (air). Structural analyses of the solid fractions revealed that the enzymatic reaction, particularly with aeration, created increased surface area (BET analysis), increased disorder (SEM analysis), decreased crystallinity (XRD), and increased dye adsorption based on the cellulose content (Simons' staining).ConclusionsThe gains in glucan conversion with aeration were larger than the decreases observed due to increased substrate content, resulting in higher glucan conversion when using aeration at the highest WIS value than when using N2 at the lowest WIS value. The increase in glucan conversion with double enzyme preparation dosage was smaller than the increase achieved with aeration. The results demonstrate the potential in using proper aeration to exploit the inherent capacity of LPMO in enzymatic saccharification of lignocellulosic substrates and provide detailed information about the characteristics of the substrate after interaction with cellulolytic enzymes.

Hyper xylanase production and potential of xylooligosaccharides formation from a novel Bacillus australimaris KS2

The study has been designed to isolate xylanase-producing bacteria and parametric optimization for maximum production. The xylanase was utilized for enzymatic hydrolysis of wheat bran (WB) and wheat bran extracted xylan (WBEx) to obtain xylooligosaccharides. The research was planned for value addition in the agriculture sector with low-cost enzyme production and its utilization in prebiotic production from agro-residue. The xylanase obtained from the new isolate Bacillus australimaris KS2 was optimized with 2.0% of 24 h inoculum supplemented with 2.0% wheat bran at pH 7, 35 °C for 48 h with an agitation rate of 150 rpm. There was a 2.96-fold increase in xylanase activity from its initial (2997.07 IU/mL) activity to the optimized condition (8873.07 IU/mL). The maximum reducing sugar production over enzymatically hydrolyzed WB was found after 8 h of reaction time at pH 5, 55 °C with 375 units of enzyme. In the case of enzymatically hydrolyzed WBEx, the maximum production of 588 mg/g was achieved after 16 h at pH 6 and 55 °C of reaction temperature at the same amount of enzyme dose. The results demonstrated that the new isolate Bacillus australimaris KS2 was an efficient xylanase producer. Xylooligosaccharides produced through enzymatic hydrolysis of WBEx showed good prebiotic potential over Lactobacillus plantarum, Lactobacillus brevis, and Lactobacillus rhamnosus.

Substrate-related factors and kinetic studies of Carbohydrate-Rich food wastes on enzymatic saccharification

Food waste biorefinery is a sustainable approach to producing green chemicals, however the essential substrate-related factors hindering the efficacy of enzymatic hydrolysis have never been clarified. This study explored the key rate-limiting parameters and mechanisms of carbohydrate-rich food after different cooking and storing methods, i.e., impacts of compositions, structural diversities, and hornification. Shake-flask enzymatic kinetics determined the optimal dosages (0.5 wt% glucoamylase, 3 wt% cellulase) for food waste hydrolysis. First order kinetics and simulation results determined that reaction coefficient (K) of cooked starchy food was ∼ 3.63 h−1 (92 % amylum digestibility) within 2 h, while those for cooked cellulosic vegetables were 0.25–0.5 h−1 after 12 h of hydrolysis. Drying and frying reduced ∼ 71–89 % hydrolysis rates for rice, while hydrothermal pretreatment increased the hydrolysis rate by 82 % on vegetable wastes. This study provided insights into advanced control strategy and reduced the operational costs by optimized enzyme doses for food waste valorization.

Intensification of corn fiber saccharification using a tailor made enzymatic cocktail

The transition from an economic model based on resource extraction to a more sustainable and circular economy requires the development of innovative methods to unlock the potential of raw materials such as lignocellulosic biomasses. Corn fiber differs from more traditional lignocellulosic biomasses due to its high starch content, which provides additional carbohydrates for fermentation-based biomanufacturing processes. Due to its unique chemical composition, this study focused on the development of a tailor made enzymatic cocktail for corn fiber saccharification into monosaccharides. Three commercially available hydrolytic enzymes (Cellic® CTec2, Pentopan® Mono BG, and Termamyl® 300 L) were combined to hydrolyze the polysaccharide structure of the three main carbohydrate fractions of corn fiber (cellulose, hemicellulose and starch, respectively). Prior to saccharification, corn fiber was submitted to a mild hydrothermal pretreatment (30 min at 100 °C). Then, two experimental designs were used to render an enzymatic cocktail capable of providing efficient release of monosaccharides. Using 60 FPU/g DM of Cellic® CTec2 and 4.62 U/g DM of Termamyl® 300 L, without addition of Pentopan® Mono BG, resulted in the highest efficiencies for glucose and xylose release (66% and 30%, respectively). While higher enzyme dosages could enhance the saccharification efficiency, adding more enzymes would have a more pronounced effect on the overall process costs rather than in increasing the efficiency for monosaccharides release. The results revealed that the recalcitrance of corn fiber poses a problem for its full enzymatic degradation. This fact combined with the unique chemical composition of this material, justify the need for developing a tailor made enzymatic cocktail for its degradation. However, attention should also be given to the pretreatment step to reduce even more the recalcitrance of corn fiber and improve the performance of the tailored cocktail, as a consequence.

On-Line Monitoring of Enzymatic Degumming of Soybean Oil Using Near-Infrared Spectroscopy.

Degumming is an oil refinement process in which the naturally occurring phospholipids in crude vegetable oils are removed. Enzymatic degumming results in higher oil yield and more cost-efficient processing compared to traditional degumming processes using only water or acid. Phospholipase C hydrolyses phospholipids into diglycerides and phosphate groups during degumming. The diglyceride content can therefore be considered a good indicator of the state of the enzymatic reaction. This study investigates the use of near-infrared (NIR) spectroscopy and chemometrics to monitor the degumming process by quantifying diglycerides in soybean oil in both off-line and on-line settings. Fifteen enzymatic degumming lab scale batches originating from a definitive screening design (with varying water, acid, and enzyme dosages) were investigated with the aim to develop a NIR spectroscopy prediction method. By applying tailored preprocessing and variable selection methods, the diglyceride content can be predicted with a root mean square error of prediction of 0.06% (w/w) for the off-line set-up and 0.07% (w/w) for the on-line set-up. The results show that the diglyceride content is a good indicator of the enzyme performance and that NIR spectroscopy is a suitable analytical technique for robust real-time diglyceride quantification.

Effect of exogenous fibrolytic enzymes cocktail incorporation on in vitro degradation and fermentation characteristics of oats straw based total mixed ration

The study was conducted to evaluate the effects of increasing doses: 0 (control), 0.20, 0.40, 0.60, 0.80 and 1.00 % DM of an exogenous fibrolytic enzymes (EFE) cocktail preparation on in vitro gas production (GP), nutrient degradability and fermentation characteristics of oats straw based Total Mixed Ration (TMR) with 60:40 roughage to concentrate ratio using sheep rumen liquor. The chemical composition of all the feed ingredients used for preparation of the experimental TMR (containing 16.63% crude protein and 90.51% organic matter) were within the normal ranges. Increasing the incorporation level of enzyme cocktail linearly as well as quadratically increased net GP, metabolisable energy content, short chain fatty acid concentrations and microbial crude protein production up to 0.60% DM level (L3) with no additional improvement at further higher levels. There were significant improvements in degradability of dry matter, organic matter and neutral detergent fibre up to the enzyme dose of 0.60% DM (L3) with constant values thereafter. Fermentation characteristics response to varying incorporation doses of EFE cocktail also revealed improvements up to 0.60% DM level (L3) with no effect on non-protein nitrogen contents. It is recommended that EFE cocktail incorporation dose of 0.60% DM to be used for efficient utilisation of oats straw based complete feed; however, this requires further testing by in vivo studies.

Influence of enzymatic modification on the basis of improved extrusion cooking technology (IECT) on the structure and properties of corn starch

Enzymatic modification can directly affect the structure and properties of starch, but generally causes high energy consumption in drying process. Improved extrusion cooking technology (IECT) itself is a starch modification technology. In this work, a co-extrusion method of starch with 42 % moisture and enzyme was adopted to reveal the effects of different enzyme dosages on the structure and properties of corn starch. After enzyme treatment on the basis of IECT, starch granules were broken into fragments without the occurrence of clear Maltese cross. R1047/1022 and R995/1022 values, peak intensity of Raman spectra and gelatinization temperature decreased, and the full width at half maximum at 480 cm−1 of Raman spectra raised. Moreover, the bound water proportion decreased from 87.44 % to 85.84 % ∼ 78.67 %, and the maximum light transmittance and dextrose equivalent values increased to 34.13 % and 26.14, respectively. The solubility of starch granules was all above 60 %. Findings supported that the mechanochemical effect of IECT on starch was conducive to the enzymatic modification.

Filtration enzymes applied during mashing affect beer composition and viscosity

Why was the work done: Filtration enzymes that target the degradation of arabinoxylan and β-glucan are widely used in the brewing industry to improve wort and beer filtration. Although these enzymes have proven their effectiveness in improved lautering efficiency and beer filterability, the effect of varying dosage and type of enzyme preparations on beer composition and quality has not been described.&#x0D; How was the work done: The impact of dosage of different filtration enzyme preparations (Laminex®750, Laminex®C2K, and Laminex®MaxFlow4G) was investigated on the free ferulic acid content in the wort, chemical composition and viscosity of beer, together with an emphasis on the content and structure of arabinoxylan and β-glucan.&#x0D; What are the main findings: The structural features of arabinoxylan and β-glucan in beer were strongly influenced by the dosage and type of filtration enzyme. In general, the high-molecular weight (HMW) arabinoxylan and HMW β-glucan content, and total β-glucan content in beers decreased with increasing enzyme dosage, while the total arabinoxylan levels increased. The HMW arabinoxylan content was strongly related to beer viscosity. The use of filtration enzymes led to a decreased HMW arabinoxylan content and decreased beer viscosity, which could affect the palate fullness of beers. Overdosing filtration enzymes resulted in more ferulic acid, the precursor (in the presence of phenolic yeast) to the clove-like 4-vinyl guaiacol.&#x0D; Why is the work important: This work provides brewers with insight on how filtration enzymes affect beer composition and viscosity. It can help make an informed choice of the type of filtration enzyme and the dosage applied during mashing.

Fed-batch SSF with pre-saccharification as a strategy to reduce enzyme dosage in cellulosic ethanol production

The pulp and paper industry is a strategic sector to be converted into a forest-based biorefinery, taking advantage of know-how, existing infrastructures and well-established logistic operations to deal with a daily high volume of forest residues. Bioethanol production from Eucalyptus globulus bark previously pretreated by kraft pulping was assessed following two configurations at the bioreactor scale: separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF). This last configuration was optimized by using a pre-saccharification and a fed-batch feeding (FB PS-SSF), allowing for a reduction in the enzyme dosage from 25 to 10 FPU gCH−1, which is very advantageous from an economic point of view. For 10 FPU gCH−1 enzyme dosage and 20 % (w/v) total solids loading, an ethanol concentration of around 70.6 g L−1 was accomplished, corresponding to overall conversion efficiency and productivity of about 78 % and 1.35 g L−1 h−1, respectively. Increasing solids loading from 20 to 26 % (w/v), using the same enzyme dosage, resulted in the highest ethanol concentration (84.6 g L−1) despite the too-long assay and the decline in productivity. Overall, FB PS-SSF improved bioethanol concentration and allowed decreased enzymatic usage over SHF, maintaining high ethanol concentration.

An in-field assembled hierarchical mesoporous electroenzymatic sensor for sensitive and real-time monitoring of nitrite

Electroenzymatic sensors are promising for nitrite detection but their application in real environmental scenarios is restricted due to the challenges in fabrication complexity and storage stability. Herein, we proposed a “drop & go” strategy to allow non-professionals to fabricate the electroenzymatic sensors in-field for monitoring the nitrite in real-time. To achieve this, hierarchical mesoporous ITO (mesoITO) electrode was prepared via a sol-gel process and a nitrite reductase NrfA originated from Shewanella oneidensis MR-1 was immobilized via a simple dropping process. Cyclic voltammetric (CV) analyses confirmed the direct electron transfer between NrfA and mesoITO electrode. After optimizing the enzyme dosage and electrochemical parameters, both CV and amperometric assays for nitrite detection were developed and a linear detection range of 10–130 μM and 1–140 μM nitrite were determined, respectively. Besides, these electroenzymatic sensors exhibited excellent resistance to the common anions in the water and good performance stability under working conditions. With this basis, the fabricated biosensors were applied for continuously monitoring the nitrite in a denitrifying process and the results were well-matched with the colorimetric method reference. More importantly, the presence of bacterial cells created favorable microenvironment for electroenzymatic nitrite reduction, and promoted the detection of trace nitrite in the bioreactor. This work developed a new methodology for fast electroenzymatic biosensor assembling, facilitate sensitive nitrite quantification in the real environment scenario, and may bring new concept for environment contaminants monitoring in real-time.

An Efficient and Cost- Effective Pretreatment of Rice Straw Using Steam Explosion: A Pilot Scale Experience

Surplus availability of rice straw (RS) presents it as a potential feedstock for ethanol production. Steam explosion (SE) is considered as a green approach to extract fermentable sugars at lower cost. The present study deals with the reaction condition optimization for water and dilute acid assisted steam explosion of rice straw at different temperatures and explores the effect of structural properties of solid residue on enzymatic hydrolysis along with mass balance. SE conditions were optimized at pilot scale, raising the temperature from 170 to 200 °C in water assisted SE resulting in an increased glucan conversion from 21.4 to 42.5% at 15% solid loading using 1.5 FPU of cellulases g–1 biomass. Further, it was improved up to 58.7% by increasing the enzyme dosage to 5 FPU, although it might lead to enhanced enzyme cost by threefold. To reduce costs, small amount of dilute acid (DA) was added during SE and lowering of enzyme consumption i.e. 1.5 FPU/g cellulose has been used to achieve 65.5% glucan conversion. Varying temperature and incorporate dilute acid during pretreatment induced structural alterations in biomass evident by compositional analysis, FT-IR and mass balance. Mass balance study revealed that the overall sugar recovery i.e. 58.7 and 38.8% and theoretical yield of ethanol shall be 222 and 186 L ton–1 RS respectively, with and without DA addition.Graphical

Low-dosage enzymatic hydrolysis of organic municipal waste for sugar and ethanol production

AbstractEnzymatic hydrolysis (EH) of the organic fraction of municipal solid waste (OFMSW) is challenging due to its complexity and heterogeneous character. This study investigated the effects of OFMSW compositional characteristics and pretreatment techniques on the efficiency of EH. The experiments involved varying enzymatic dosages and pretreatment methods, including heat pretreatment and anaerobic incubation of raw OFMSW. Remarkably, after thermal pretreatment, a saccharification yield exceeding 50% was achieved with only 1 filter paper unit (FPU) of Cellic® Ctec3 and 0.5 glucoamylase unit (AGU) of AMG® 300 L BrewQ per g of dry OFMSW. This resulted in the recovery of 239 g of sugar per kilogram of dry OFMSW. The study revealed that the decomposition of OFMSW by enzymes is limited after reaching about 50% of the sugar recovery yield, and high concentrations of inhibitors such as organic acids, alcohols, and potentially other organics and inorganics may contribute to this limitation. These compounds, however, serve as excellent preservatives, achieving contamination control during biological conversion. Sugar-rich hydrolysates were subjected to ethanol fermentation using Saccharomyces cerevisiae, leading to the conversion of most hexose sugars into ethanol, reaching 331 g of ethanol per kilogram of dry OFMSW, and indicating that the limitation of OFMSW saccharification was not due to product inhibition. These findings highlight the need for further investigation of the saccharification process of biowaste to overcome inhibitory effects and subsequently achieve higher efficiency of the following bioprocesses.