Selection Of Biocatalysts Research Articles

Syngas fermentation to ethanol: CODH/AdhE1 gene expression and microbial community dynamics

C1-gas conversion for sustainable synthesis of fatty acids and ethanol: dynamics of CODH/AdhE1 gene expression with biocatalyst selection.

Encapsulation of peroxidase on hydrogel sodium polyacrylate spheres incorporated by silver and gold nanoparticles: A comparative study

The selectivity of biocatalysts based on enzymes, eco-friendly reaction systems, and strong catalyst performance is exceptionally compelling. For improving enzyme recyclability and stability, a good option that has been proved is immobilization. For enzyme immobilization, hydrogel sodium polyacrylate combined with nanoparticles is an interesting class of support matrices as compared to others. This study synthesizes and uses the cross-linked hydrogel sodium polyacrylate-decorated gold or silver nanoparticles (HSP/AuNPs or AgNPs) as immobilized support for peroxidase and FTIR characterizes it. The novel supports immobilized system properties enhanced biocompatibility. They have attained a greater immobilization yield (91% with HSP/AuNPs and 84% with HSP/AgNPs). The rest of the immobilized peroxidase activity, after 10 recurring cycles of HSP/AuNPs was 61% and HSP/AgNPs was 54%. The remaining activity of the immobilized enzyme onto HSP/AgNPs, after storing at 4°C for 6 weeks, was 73% and HSP/AuNPs was 75% of its initial activity. It was revealed that the optimum temperature for the free enzyme and the immobilized enzyme was 50°C and 50–60°C, respectively. For the immobilized enzyme, the optimum pH is 7–7.5, as compared to the optimum pH of free enzyme pH 6.5.

Regiospecific Hydrogenation of Bromochalcone by Unconventional Yeast Strains.

This research aimed to select yeast strains capable of the biotransformation of selected 2′-hydroxybromochalcones. Small-scale biotransformations were carried out using four substrates obtained by chemical synthesis (2′-hydroxy-2″-bromochalcone, 2′-hydroxy-3″-bromochalcone, 2′-hydroxy-4″-bromochalcone and 2′-hydroxy-5′-bromochalcone) and eight strains of non-conventional yeasts. Screening allowed for the determination of the substrate specificity of selected microorganisms and the selection of biocatalysts that carried out the hydrogenation of tested compounds in the most effective way. It was found that the position of the bromine atom has a crucial influence on the degree of substrate conversion by the tested yeast strains. As a result of the biotransformation of the 2′-hydroxybromochalcones, the corresponding 2′-hydroxybromodihydrochalcones were obtained. The products obtained belong to the group of compounds with high potential as precursors of sweet substances.

Maximizing net fuel economy improvement from fusel alcohol blends in gasoline using multivariate optimization

Fusel alcohol mixtures containing ethanol, isobutanol, isopentanol, and 2-phenylethanol have been shown to be a promising means to maximize renewable fuel yield from various biomass feedstocks and waste streams. We hypothesized that use of these fusel alcohol mixtures as a blending agent with gasoline can significantly lower the greenhouse gas emissions from the light-duty fleet. Since the composition of fusel alcohol mixtures derived from fermentation is dependent on a variety of factors such as biocatalyst selection and feedstock composition, multi-objective optimization was performed to identify optimal fusel alcohol blends in gasoline that simultaneously maximize thermodynamic efficiency gain and energy density. Pareto front analysis combined with fuel property predictions and a Merit Score-based metric led to prediction of optimal fusel alcohol-gasoline blends over a range of blending volumes. The optimal fusel blends were analyzed based on a Net Fuel Economy Improvement Potential metric for volumetric blending in a gasoline base fuel. The results demonstrate that various fusel alcohol blends provide the ability to maximize efficiency improvement while minimizing increases to blending vapor pressure and decreases to energy density compared to an ethanol-only bioblendstock. Fusel blends exhibit predicted Net Fuel Economy Improvement Potential comparable to neat ethanol when blended with gasoline in all scenarios, with increased improvement over ethanol at moderate to high bio-blendstock blending levels. The optimal fusel blend that was identified was a mixture of 90% v/v isobutanol and 10% v/v 2-phenylethanol, blended at 45% v/v with gasoline, yielding a predicted 4.67% increase in Net Fuel Economy Improvement Potential. These findings suggest that incorporation of fusel alcohols as a gasoline bioblendstock can improve both fuel performance and the net fuel yield of the bioethanol industry.

Biocatalytic Process Optimization

Biocatalysis refers to the use of microorganisms and enzymes in chemical reactions, has become increasingly popular and is frequently used in industrial applications due to the high efficiency and selectivity of biocatalysts [...]

Rapid Protocol for Screening of Biocatalyst for Application in Microbial Fuel Cell: A Study with Shewanella algae

Due to energy expansion and sustainable development of resources and systems, there has been an increasing demand for environmentally friendly alternative energy systems. Microbial fuel cells (MFCs) are considered one of the most promising alternative energy generation systems. The microorganism is one of the key limiting factors to enhance the performance efficiency of MFC. Therefore, proper evaluation of screening protocol is imperative benchmarks for selection of biocatalyst in MFC. In the present study, an attempt was taken for rapid evaluation of iron-reduction capacity and growth of Shewanella algae through optimization of process parameters using Taguchi methodology. Here, five process parameters, including lactose, trace element, inoculum percentage, pH, and temperature, were taken into consideration as imperative factors and were optimized for evaluation of iron-reduction analysis along with growth of bacteria. The main effect of each parameter, along with their interaction influence and optimal value, was determined using a signal-to-noise (S/N) ratio. The evaluation of quality characteristics of each parameter was also determined in Taguchi robust methodology using S/N ratio. Analysis of variance was performed to assess statistically important process parameters. Predicted results exhibited that enhanced bacterial growth (120%) and iron-reduction capacity (114%) can be achieved with 8 g/L of lactose, 2 mL of trace element solution, 7 of initial pH, 30 °C of temperature, and 4% (v/v) of inoculum percentage. It is evident from the results that Shewanella algae can be used as a promising catalyst for MFC.

One‐Pot Transformation of Ketoximes into Optically Active Alcohols and Amines by Sequential Action of Laccases and Ketoreductases or ω‐Transaminases

AbstractAn enzymatic one‐pot process for asymmetric transformation of prochiral ketoximes into alcohols or amines was developed by sequential coupling of a laccase‐catalyzed deoximation either with a ketone reduction (ketoreductase, KRED) or bioamination (ω‐transaminase, ω‐TA) in aqueous medium. An accurate selection of biocatalysts provided the corresponding products in excellent enantiomeric excesses and overall conversions ranging from 83 to >99 % for alcohols and 70 to >99 % for amines. Likewise, the employment of exclusively 1 % (w/w) of Cremophor®, a polyethoxylated castor oil, as co‐solvent enabled to reach concentrations up to 100 mM in the chiral alcohols cascade.

Textile recycling processes, state of the art and current developments: A mini review.

World fibre production has been rising continuously over last decades and a tremendous increase is expected in the near future. The major portion of fibres goes to the textile industry whose main output streams are apparel and home textiles. With the transformation of these textile products from a basic human need to fashion items, their lifetime before disposal is steadily declining, while at the same time the complexity of their material composition is increasing. As a matter of fact, the amount of disposed items is increasing distinctively and the issue of a proper handling of end-of-life textiles is becoming more important. The objective of this mini review is, first to give a brief overview of the already available textile recycling methods, and subsequently it will discuss innovative developments of new recycling processes in the textile recycling sector. A special focus of this review lies on the emerging field of biochemical fibre recycling processes, which could become a major step on the way to a circular economy in the textile processing chain. Owing to the high selectivity of bio-catalysts, enzymes, these processes could be used to remove a specific fibre material from multi-component textiles. As the complexity of textiles is reduced, the recyclability is increased.

Fermentation Titer Optimization and Impact on Energy and Water Consumption during Downstream Processing.

A common focus of fermentation process optimization is the product titer. Different strategies to boost fermentation titer target whole‐cell biocatalyst selection, process control, and medium composition. Working at higher product concentrations reduces the water that needs to be removed in the case of aqueous systems and, therefore, lowers the cost of downstream separation and purification. Different approaches to achieve higher titer in fermentation are examined. Energy and water consumption data collected from different Cargill fermentation plants, i.e., ethanol, lactic acid, and 2‐keto‐L‐gulonic acid, confirm that improvements in fermentation titer play a decisive role in downstream economics and environmental footprint.

A Method of Early Phase Selection of Carrier for Aspergillus Oryzae β-Galactosidase Immobilization for Galactooligosaccharides Production.

Early phase development of industrial immobilized biocatalysts has to address the selection of the best candidates from dozens of available carriers and binding methods. This work presents a simple selection method for the immobilization of industrial-grade Aspergillus oryzae β-galactosidase suitable for the production of galactooligosaccharides. Immobilization efficiency and yield of a variety of immobilized biocatalysts are evaluated using simple activity measurements and mathematical modeling of intraparticle kinetics and mass transfer. Activated carriers and some ion-exchange carriers provided highly active biocatalysts and are therefore selected for the investigation of GOS production in the batch reactor. Biocatalysts exhibited significant differences in the yield of galactooligosaccharides and productivity of GOS formation. Based on these process performance criteria, cost considerations are made that allow further selection of the best biocatalyst for future process optimization. The presented method of biocatalyst selection can be useful for other industrial enzymes applications.

SPECIFICITY OF CHANGE IN SORPTION CAPACITY OF FLAX FIBER UNDER REGULABLE BIO-CATALYTICAL DESTRUCTION OF NEUTRAL CARBOHYDRATES

Evaluation of the nano sizes of hydrosols from homogeneous cellulosic and industrial products was made using dynamic light scattering method. The influence of the size of the globule of protein catalysts and the duration of their action on the roving of carded flax fiber was compared. The correlation between the change in the equilibrium absorption of sorption marker (methylene blue) and residual content in the fiber of hemicelluloses was monitored. On the basis of a comparative analysis of the efficiency of biocatalysts in industrial homogeneous and cellulosic preparations it was revealed that globule size influences on the efficiency of sorption properties of flax fibers. The use of homogeneous enzymes with differing sized parameters has allowed isolating the contribution of the target enzymatic modification as in the microfibrillar structure of elementary fibers and for modification the hemicelluloses in the binding substance fixing the elementary fibers in the bast bundles (the linen fibrous complexes). The principles of selection of biocatalysts to increase sorption capacity in flax fiber sorbents were revealed. It was found that the sorption capacity of flax fiber sorbents increases due to the development of mezopore space in elementary fibres and regulable amorphization of interfiber binders in the structure of the linen complex. The research revealed that the the amorphization of flax fiber took place only when the cellulases was used. The size of their globules enables the penetration of these enzymes into mesopores of elementary flax fibres. It was established experimentally that the presence of large isoforms of cellulases or hemicellulases can promote as the development of the internal volume into the fibre binders and also conservation the permissible level of reduction of the hemicelluloses amount in flax fibres is not less than 10 mass.%.Forcitation:Aleeva S.V., Lepilova O.V., Kurzanova P.Yu., Koksharov S.A. Specificity of change in sorption capacity of flax fiber under regulable bio-catalytical destruction of neutral carbohydrates. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 2. P. 80-85

Customized microscale approach for optimizing two-phase bio-oxidations of alkanes with high reproducibility

BackgroundNumerous challenges remain to achieve industrially competitive space–time yields for bio-oxidations. The ability to rapidly screen bioconversion reactions for characterization and optimization is of major importance in bioprocess development and biocatalyst selection; studies at conventional lab scale are time consuming and labor intensive with low experimental throughput. The direct ω-oxyfunctionalization of aliphatic alkanes in a regio- and chemoselective manner is efficiently catalyzed by monooxygenases such as the AlkBGT enzyme complex from Pseudomonas putida under mild conditions. However, the adoption of microscale tools for these highly volatile substrates has been hindered by excessive evaporation and material incompatibility.ResultsThis study developed and validated a robust high-throughput microwell platform for whole-cell two-liquid phase bio-oxidations of highly volatile n-alkanes. Using microwell plates machined from polytetrafluoroethylene and a sealing clamp, highly reproducible results were achieved with no significant variability such as edge effects determined. A design of experiment approach using a response surface methodology was adopted to systematically characterize the system and identify non-limiting conditions for a whole cell bioconversion of dodecane. Using resting E. coli cells to control cell concentration and reducing the fill volume it is possible to operate in non-limiting conditions with respect to oxygen and glucose whilst achieving relevant total product yields (combining 1-dodecanol, dodecanal and dodecanoic acid) of up to 1.5 mmol gDCW−1.ConclusionsOverall, the developed microwell plate greatly improves experimental throughput, accelerating the screening procedures specifically for biocatalytic processes in non-conventional media. Its simplicity, robustness and standardization ensure high reliability of results.

Enzyme‐Promoted Asymmetric Tandem Passerini Reaction

AbstractA versatile and highly efficient three‐step, one‐pot, enzyme‐promoted Passerini tandem reaction has been developed. The chemoenzymatic sequence involved simultaneous enzyme catalyzed hydrolysis, subsequent Passerini reaction, and enzymatic kinetic resolution of the Passerini product. This methodology combines the diversity delivered by multicomponent reactions with the selectivity of biocatalysts, which results in efficient synthesis of the target compounds with excellent enantiomeric excesses of up to 99 %. With a small set of substrates, a large library of complex molecules was obtained within a short time by using the developed procedure.

Changing the Selectivity of Biocatalysts

Changing the Selectivity of Biocatalysts

Molecular characterization of a novel oligoalginate lyase consisting of AlgL- and heparinase II/III-like domains from Stenotrophomonas maltophilia KJ-2 and its application to alginate saccharification

Molecular identification and development of a novel recombinant alginate lyase as the biocatalyst for alginate saccharification are prerequisite for bioethanol fermentation from brown seaweed biomass. We identified and characterized a novel oligoalginate lyase for complete degradation of alginate from Stenotrophomonas maltophilia KJ-2 that grow on alginate as the sole carbon source. KJ-2 oligoalginate lyase consisted of AlgL- and heparinase II/III-like domains. The recombinant KJ-2 oligoalginate lyase exhibited substrate preference toward polymannuronate and alginate as well as oligoalginate. The recombinant KJ-2 oligoalginate lyase completely degraded alginate into unsaturated uronate monomer most efficiently at pH 7.5 and 37 °C. Interestingly, AlgL-like recombinant proteins showed more like endolytic activity. The recombinant KJ-2 oligoalginate lyase was a novel oligoalginate lyase consisting of AlgL- and heparinase-like domains and could be used as a candidate for biocatalyst selection to saccharify alginate for bioethanol production from brown seaweed.

Enzymatic production of lactulose and 1-lactulose: current state and perspectives

Lactulose, a synthetic ketose disaccharide, has been widely used in food and pharmaceutical industries as prebiotic food additives and drugs against constipation and hepatic encephalopathy. Lactulose has, so far, been produced chemically using lactose on a commercial scale. The key problems associated with such chemical process are the cost of removal of the catalyst and colored by-products and the product safety. Enzymatic production of lactulose is safe, environment-friendly, and simpler in comparison to the chemical method. As a promising alternative to the chemical method, enzymatic conversion of lactose into lactulose by β-galactosidase or cellobiose 2-epimerase has recently gained a great deal of attention. This could be considered as a possible route for whey surplus because lactose is the major component of cheese whey. Herein, we summarize recent advances on the enzymatic synthesis of lactulose with emphasis on the selectivity of biocatalysts and their catalytic efficiency in free and immobilized forms. The production of 1-lactulose by enzymatic bioconversion of lactose has also been discussed. Furthermore, future research needs of β-galactosidase and cellobiose 2-epimerase for the enzymatic synthesis of lactulose and 1-lactulose are reviewed.

Stereoselective Friedel–Crafts alkylation catalyzed by squalene hopene cyclases

In organic synthesis the Friedel–Crafts alkylation is of eminent importance, as it is a key reaction in many synthetic routes. A general access to enzymatic Friedel–Crafts alkylations would be very beneficial due to the high selectivity of biocatalysts. We used designed polyprenyl phenyl ethers to specifically address this reaction by using squalene hopene cyclases as catalysts. Polycyclic products with aromatic rings constituting important biological active compounds were obtained. Our results demonstrate that squalene hopene cyclases can be utilized for Friedel–Crafts alkylations and reveal the potential of these enzymes for chiral Brønsted acid catalysis.

Selection of a whole-cell biocatalyst for methyl parathion biodegradation

Whole-cell biocatalyst has the potential to become a cost-effective alternative to conventional enzyme methods for solving ecological and energy issues. However, cytosolic-expressing biocatalyst systems are critically disadvantaged due to the low permeability of the cell membrane. To overcome substrate transport barrier, periplasmic secretion and surface display biocatalysts were developed by expressing signal peptides or anchor proteins in Escherichia coli. In this work, six carriers were compared in regard to whole-cell activity of methyl parathion hydrolase (MPH). Our results indicate that the surface display systems yielded one to three times whole-cell activity than the periplasmic secretion systems. Although periplasmic secretion systems showed generally more stable than surface display systems, surface display appeared more suitable for whole-cell biocatalyst. It should note that the applicability of the DsbA/PhoA/AIDA-I leader to MPH expression is shown here for the first time. In addition, the result provided a useful reference for other whole-cell biocatalyst selection.

Biocatalysis: Synthesis of Key Intermediates for Development of Pharmaceuticals

Chirality is a key factor for the safety and efficacy of many drug products. The production of single enantiomers of drug intermediates has become increasingly important in the pharmaceutical industry. There has been an enormous potential of microorganisms and enzymes derived from there for the transformation of synthetic chemicals with high chemo-, regio-, and enatioselectivities. Recent development in the area of directed evolution has led screen mutants under process conditions to increase activity and selectivity of biocatalysts, thus making the enzymatic process highly efficient and economically feasible. In this review, chemoenzymatic processes are described for the synthesis of chiral intermediates for the development of pharmaceuticals.

Biotransformations in microstructured reactors: more than flowing with the stream?

The state of the art in the application of microstructured flow reactors for biocatalytic process research is reviewed. A microstructured reactor that is fully automated and analytically equipped presents a powerful screening tool with which to perform biocatalyst selection and optimization of process conditions at intermediary stages of process development. Enhanced mass transfer provided by the microstructured reactor can be exploited for process intensification, particularly during multiphase biocatalytic processing where mass transfer across phase boundaries is often limiting. Reversible immobilization of enzymes in microchannels remains a challenge for flexible realization of biotransformations in microstructured reactors. Compartmentalization in microstructured reactors could be useful in performing multistep chemoenzymatic conversions.