Nitrilase immobilization and transposition from a micro-scale batch to a continuous process increase the nicotinic acid productivity

Prospects of formamide as nitrogen source in biotechnological production processes

This review presents an analysis of formamide, focussing on its occurrence in nature, its functional roles, and its promising applications in the context of the bioeconomy. We discuss the utilization of formamide as an innovative nitrogen source achieved through metabolic engineering. These approaches underscore formamide's potential in supporting growth and production in biotechnological processes. Furthermore, our review illuminates formamide's role as a nitrogen source capable of safeguarding cultivation systems against contamination in non-sterile conditions. This attribute adds an extra layer of practicality to its application, rendering it an attractive candidate for sustainable and resilient industrial practices. Additionally, the article unveils the versatility of formamide as a potential carbon source that could be combined with formate or CO2 assimilation pathways. However, its attributes, i.e., enriched nitrogen content and comparatively limited energy content, led to conclude that formamide is more suitable as a co-substrate and that its use as a sole source of carbon for biomass and bio-production is limited. Through our exploration of formamide's properties and its applications, this review underscores the significance of formamide as valuable resource for a large spectrum of industrial applications. KEY POINTS: • Formidases enable access to formamide as source of nitrogen, carbon, and energy • The formamide/formamidase system supports non-sterile fermentation • The nitrogen source formamide supports production of nitrogenous compounds.

Molecular Modification Strategies of Nitrilase for Its Potential Application in Agriculture

Some feed source plants will produce secondary metabolites such as cyanogenic glycosides during metabolism, which will produce some poisonous nitrile compounds after hydrolysis and remain in plant tissues. The consumption of feed-source plants without proper treatment affect the health of the animals' bodies. Nitrilases can convert nitriles and have been used in industry as green biocatalysts. However, due to their bottleneck problems, their application in agriculture is still facing challenges. Acid-resistant nitrilase preparations, high-temperature resistance, antiprotease activity, strong activity, and strict reaction specificity urgently need to be developed. In this paper, the application potential of nitrilase in agriculture, especially in feed processing industry was explored, the source properties and catalytic mechanism of nitrilase were reviewed, and modification strategies for nitrilase application in agriculture were proposed to provide references for future research and application of nitrilase in agricultural and especially in the biological feed scene.

Wall-Immobilized Biocatalyst vs. Packed Bed in Miniaturized Continuous Reactors: Performances and Scale-Up

Sustainable biocatalysis syntheses have gained considerable popularity over the years. However, further optimizations - notably to reduce costs - are required if the methods are to be successfully deployed in a range of areas. As part of this drive, various enzyme immobilization strategies have been studied, alongside process intensification from batch to continuous production. The flow bioreactor portfolio mainly ranges between packed bed reactors and wall-immobilized enzyme miniaturized reactors. Because of their simplicity, packed bed reactors are the most frequently encountered at lab-scale. However, at industrial scale, the growing pressure drop induced by the increase in equipment size hampers their implementation for some applications. Wall-immobilized miniaturized reactors require less pumping power, but a new problem arises due to their reduced enzyme-loading capacity. This review starts with a presentation of the current technology portfolio and a reminder of the metrics to be applied with flow bioreactors. Then, a benchmarking of the most recent relevant works is presented. The scale-up perspectives of the various options are presented in detail, highlighting key features of industrial requirements. One of the main objectives of this review is to clarify the strategies on which future study should center to maximize the performance of wall-immobilized enzyme reactors.

Redefining the Glyphosate Sector: Harmonizing Inventiveness and Sustainable Practices for a Better World

The glyphosate industry has long been a critical player in global agriculture, providing effective and economical solutions for weed control. However, growing concerns over environmental and health impacts have led to increased scrutiny and calls for more sustainable practices. This Viewpoint focuses on the scientific aspects of greener glyphosate synthesis strategies, discussing recent advancements in biobased pathways and catalytic methods, challenges such as scalability and technical hurdles, and future prospects for the herbicide industry. By embracing these new techniques, we can ensure a more sustainable future for herbicide production and contribute to a healthier world.

Process intensification in continuous flow biocatalysis by up and downstream processing strategies

In this review, we focus on the holistic continuous enzymatic production and put special emphasis on process intensification by up- and downstream processing in continuous flow biocatalysis. After a brief introduction, we provide an overview of current examples of enzyme immobilization as an upstream process for flow biocatalysis. Thereafter, we provide an overview of unit operations as downstream processing strategies, namely continuous (i) liquid-liquid extraction, (ii) adsorptive downstream processing, and (iii) crystallization and precipitation. Eventually, we present our perspectives on future trends in this research field.

Preparation, characterization and stability of cross linked nitrilase aggregates (nitrilase-CLEAs) for hydroxylation of 2-chloroisonicotinonitrile to 2-chloroisonicotinic acid

Nitrilases capable of performing hydroxylation of 2-chloroisonicotinonitrile to 2-chloroisonicotinic acid were screened, and ES-NIT-102 was the best nitrilase for said biotransformation. Nitrilase was immobilized as cross linked enzyme aggregates (nitrilase-CLEAs) by fractional precipitation with iso-propanol, and cross linked with glutaraldehyde. The nitrilase-CLEAs prepared with optimized 35 mM glutaraldehyde for 120 min cross linking time had 82.36 ± 4.45% residual activity, and displayed type-II structural CLEAs formation as confirmed by particle size, SEM, FTIR, and SDS-PAGE analysis. Nitrilase-CLEAs had superior pH and temperature stability, showed a shift in optimal temperature by 5 °C, and retained nearly 1.5 to 1.7 folds activity over free nitrilase at 50 °C and 55 °C after more than 9 h incubation. Nitrilase-CLEAs showed reduced affinity and decreased conversion of substrate as indicated by slightly higher K_m values by 5.19% and reduced V_max by 17%. Furthermore, these nitrilase-CLEAs showed 98% conversion, 94.72 g/L product formation, and 83.30% recovery after 24 h when used for hydroxylation of 2-chloroisonicotinonitrile to 2-chloroisonicotinic acid. Nitrilase-CLEAs were catalytically active for 3 cycles showcasing 81% conversion, 75.53 g/L product formation and 66.42% yield. The recovered product was confirmed by HPLC, FTIR, LC-MS, and ¹H NMR, and displayed > 99% purity.

Engineering of reaction specificity, enantioselectivity and catalytic activity of nitrilase for highly efficient synthesis of pregabalin precursor

Simultaneous evolution of multiple enzyme properties remains challenging in protein engineering. A chimeric nitrilase (BaNIT_M0 ) with high activity towards isobutylsuccinonitrile (IBSN) was previously constructed for biosynthesis of pregabalin precursor (S)-3-cyano-5-methylhexanoic acid ((S)-CMHA). However, BaNIT_M0 also catalyzed the hydration of IBSN to produce by-product (S)-3-cyano-5-methylhexanoic amide. In order to obtain industrial nitrilase with vintage performance, we carried out engineering of BaNIT_M0 for simultaneous evolution of reaction specificity, enantioselectivity and catalytic activity. The best variant V82L/M127I/C237S (BaNIT_M2 ) displayed higher enantioselectivity (E=515), increased enzyme activity (5.4-fold) and reduced amide formation (from 15.8% to 1.9 %) compared with BaNIT_M0 . Structure analysis and molecular dynamics simulations indicated that mutation M127I and C237S restricted the movement of E66 in the catalytic triad, resulting in decreased amide formation. Mutation V82L was incorporated to induce the reconstruction of the substrate binding region in the enzyme catalytic pocket, engendering the improvement of stereoselectivity. Enantio- and regio-selective hydrolysis of 150 g/L IBSN using 1.5 g/L E. coli cells harboring BaNIT_M2 as biocatalyst afforded (S)-CMHA with >99.0% ee and 45.9% conversion, which highlighted the robustness of BaNIT_M2 for efficient manufacturing of pregabalin. This article is protected by copyright. All rights reserved.

Microfluidic fabrication of tunable alginate-based microfibers for the stable immobilization of enzymes

Immobilized enzymes have drawn extensive attention due to their enhanced stability, easy separation from reaction mixture, and prominent recyclability. Nevertheless, it is still an ongoing challenge to develop potent immobilization techniques which are capable of stable enzyme encapsulation, minimal loss of activity, and modulability for various enzymes and applications. Here, microfibers with tunable size and composition were fabricated using a home-made microfluidic device. These microfibers were able to efficiently encapsulate bovine serum albumin (BSA), glucose oxidase (GOx), and horseradish peroxidase (HRP). But the physically adsorbed enzymes readily diffused into the catalytic reaction system. The leakage of enzymes could be substantially inhibited by conjugating to polyacrylic acid (PAA) and incorporating into alginate-based microfibers, enabling stable immobilization, improved recyclability, and enhanced thermostability. In addition, GOx and HRP-loaded microfibers were fabricated under the optimized conditions for the visual detection of glucose using the cascade reaction of these enzymes, showing sensitive color change to glucose with concentration range of 0-2 mM. Due to the tunability and versatility, this microfluidic-based microfiber platform may provide a valuable approach to the enzyme immobilization for the cascade catalysis and diagnoses with multiple clinical markers. This article is protected by copyright. All rights reserved.

Constitutive expression of nitrilase from Rhodococcus zopfii for efficient biosynthesis of 2-chloronicotinic acid

2-chloronicotinic acid (2-CA) is a key precursor for the synthesis of a series of pesticides and pharmaceuticals. Nitrilase-catalyzed bioprocess is a promising method for 2-CA production from 2-chloronicotinonitrile (2-CN). In this study, a mutant of nitrilase from Rhodococcus zopfii (RzNIT/W167G) was constitutively overexpressed with Escherichia coli as host, which exhibited a onefold increase in enzymatic activity compared with inducible expression. Biosynthesis of 2-CA using whole cells harboring nitrilase as biocatalysts were investigated and 318.5 mM 2-CA was produced, which was the highest level for 2-CA production catalyzed by nitrilase to date. 2-CA was recovered from the reaction mixture through a simple acidification step with a recovery yield of 90%. This study developed an efficient bioprocess for 2-CA with great potential for industrial application.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-022-03119-0.