Biosynthesis of nicotinic acid from 3-cyanopyridine by a newly isolated Fusarium proliferatum ZJB-09150

Maximizing the potential of nitrilase: Unveiling their diversity, catalytic proficiency, and versatile applications

Nitrilases represent a distinct class of enzymes that play a pivotal role in catalyzing the hydrolysis of nitrile compounds, leading to the formation of corresponding carboxylic acids. These enzymatic entities have garnered significant attention across a spectrum of industries, encompassing pharmaceuticals, agrochemicals, and fine chemicals. Moreover, their significance has been accentuated by mounting environmental pressures, propelling them into the forefront of biodegradation and bioremediation endeavors. Nevertheless, the natural nitrilases exhibit intrinsic limitations such as low thermal stability, narrow substrate selectivity, and inadaptability to varying environmental conditions. In the past decade, substantial efforts have been made in elucidating the structural underpinnings and catalytic mechanisms of nitrilase, providing basis for engineering of nitrilases. Significant breakthroughs have been made in the regulation of nitrilases with ideal catalytic properties and application of the enzymes for industrial productions. This review endeavors to provide a comprehensive discourse and summary of recent research advancements related to nitrilases, with a particular emphasis on the elucidation of the structural attributes, catalytic mechanisms, catalytic characteristics, and strategies for improving catalytic performance of nitrilases. Moreover, the exploration extends to the domain of process engineering and the multifarious applications of nitrilases. Furthermore, the future development trend of nitrilases is prospected, providing important guidance for research and application in the related fields.

An improved process for synthesis of nicotinic acid using hyper induced whole cell nitrilase of Gordonia terrae MTCC8139

Nitrilase mediated synthesis of nicotinic acid (vitamin B3) from 3-cyanopyridine has emerged as promising viable alternative to its chemical synthesis. In the present investigation, the nitrilase production in Gordonia terrae MTCC8139 has been increased by two fold with inducer feeding approach [i.e. the addition of 0.5% (v/v) isobutyronitrile as inducer at 0, 16 and 24 h of incubation of the culture]. The use of hyper induced whole cell nitrilase of G. terrae as biocatalyst (10 U per ml reaction) to synthesize nicotinic acid from 3-cyanopyridine in a fed batch reaction at one litre scale resulted in accumulation of 1.65 M (202 g) nicotinic acid in 330 min. The catalytic productivity of hyper induced whole cell nitrilase was increased from 8.95 to 15.3 g/h/g dcw and the reaction time was reduced to half. This is the highest productivity of nicotinic acid in a nitrilase mediated process so far reported. The achievements of the present investigation will lead to mitigate the cost of nitrilase vis-a-vis nicotinic acid production at large scale.

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

In recent years, many biocatalytic processes have been developed for the production of chemicals and pharmaceuticals. In this context, enzyme immobilization methods have attracted attention for their advantages, such as continuous production and increased stability. Here, enzyme immobilization methods and a collection of nitrilases from biodiversity for the conversion of 3-cyanopyridine to nicotinic acid were screened. Substrate conversion over 10 conversion cycles was monitored to optimize the process. The best immobilization conditions were found with cross-linking using glutaraldehyde to modify the PMMA beads. This method showed good activity over 10 cycles in a batch reactor at 30 and 40°C. Finally, production with a new thermostable nitrilase was examined in a continuous packed bed reactor, showing very high stability of the biocatalytic process at a flow rate of 0.12 ml min^-1 and a temperature of 50°C. The complete conversion of 3-cyanopyridine was obtained over 30 days of operation. Future steps will concern reactor scale-up to increase the production rate with reasonable pressure drops.

Nitrilase: a promising biocatalyst in industrial applications for green chemistry

Nitrilases are widely distributed in nature and are able to hydrolyze nitriles into their corresponding carboxylic acids and ammonia. In industry, nitrilases have been used as green biocatalysts for the production of high value-added products. To date, biocatalysts are considered to be important alternatives to chemical catalysts due to increasing environmental problems and resource scarcity. This review provides an overview of recent advances of nitrilases in aspects of distribution, enzyme screening, molecular structure and catalytic mechanism, protein engineering, and their potential applications in industry.

Endophytic Fungi of Native Salvia abrotanoides Plants Reveal High Taxonomic Diversity and Unique Profiles of Secondary Metabolites

Endophytic fungi are often embedded in their host's metabolic networks, which can result in alterations of metabolite production and higher amounts of active compounds in medicinal plants. This study reports the occurrence, diversity, and secondary metabolite profiles of endophytic fungi isolated from Salvia abrotanoides plants obtained from three geographically distinct sites in Iran. A total of 56 endophytic fungi were isolated from roots and leaves of S. abrotanoides; site-specificity and root-dominated colonization was found to be a general characteristic of the endophytes. Based on molecular identification, the endophytic fungi were classified into 15 genera. Mycelial extracts of these isolates were subjected to high-resolution mass spectrometry analyses and revealed a broad spectrum of secondary metabolites. Our results demonstrated that Penicillium canescens, P. murcianum, Paraphoma radicina, and Coniolariella hispanica are producers of cryptotanshinone, which is a main bioactive compound of S. abrotanoides. Moreover, it was shown that it can be produced independent of the host plant. The effect of exogenous gibberellin on S. abrotanoides and endophytic fungi was shown to have a positive effect on increasing the cryptotanshinone production in the plant as well as in endophytic fungi cultivated under axenic conditions. Our findings provide further evidence that endophytic fungi play an important role in the production plant bioactive metabolites. Moreover, they provide an exploitable basis to increase cryptotanshinone production in S. abrotanoides.

Efficient biocatalytic synthesis of nicotinic acid by recombinant nitrilase via high density culture

The constitutively expression system for P. putida nitrilase was firstly constructed to improve the nicotinic acid production and reduce the production costs. High density culture strategy was employed to enhance the biomass and nitrilase production of recombinant strain. The total nitrilase activity reached up to 654 U·mL^-1 without the induction. 541 g·L^-1 nicotinic acid was accumulated via fed batch mode of substrate feeding through 290 min of conversion.

Production and Characterization of a Nitrilase from Pseudomonas aeruginosa RZ44 and its Potential for Nitrile Biotransformation

BACKGROUND

The conversion of nitriles into amides or carboxylic acids by nitrilase has taken its application into consideration, as the scope of its applications has recently been extended.

OBJECTIVES

In this study, P. aeruginosa RZ44 was isolated from sewage in the Kerman which has Nitrile-degradation activity. In order to improve the nitrilase production, several optimization were done on environmental condition. Nitrilase activity was characterized against different pHs, temperatures, ions, and substrates.

MATERIALS AND METHODS

Enzyme activity was evaluated by determining the production of ammonia following to the modification of the phenol/hypochlorite method. Different factors that affect production of the enzyme by P. aeruginosa RZ44 were optimized and evaluated in the culture mediums.

RESULTS

The results showed that degradation of the acetonitrile by P. aeruginosa RZ44 increased the pH of the growth medium from the initial pH 7.0 to 9.37. Optimizing the medium for P. aeruginosa RZ44, it was found that glucose and starch (5 g.L-1) have strongly supported nitrilase production, compared to the control. As well, urea (5 g.L-1) and yeast extract (15 g.L-1) have favored an increased biomass and nitrilase production, as the nitrogen sources. These results show that nitrilase production increases in the pH range 5.0 to 7.0 and then start decreasing. Addition of the Mg2+, Fe2+ and Na+ has supported the biomass and nitrilase production. Co2+, Mn2+ and Cu2+ were confirmed to inhibit cell growth and enzyme production. Enzyme characterization results show that, P. aeruginosa RZ44 nitrilase exhibits comparatively high activity and stability at pH 7.0 and 40°C. Nitrilase was completely inhibited by CoCl2 and CaCl2, whereas, the inhibition in the presence of MnSO4 and CuSO4 was about 60%. Time course analysis of the nitrile conversion by the resting P. aeruginosa RZ44 cells showed that nitrile substrates (i.e. acetonitrile) was hydrolyzed within 8 h.

CONCLUSIONS

these results indicate that P. aeruginosa RZ44 has the potential to be applied in the biotransformation of nitrile compounds.

Cloning and functional characterization of nitrilase from Fusarium proliferatum AUF-2 for detoxification of nitriles

A fungal nitrilase gene from Fusarium proliferatum AUF-2 was cloned through reverse transcription-PCR. The open reading frame consisted of 903 bp and potentially encoded a protein of 301 amino acid residues with a theoretical molecular mass of 33.0 kDa. The encoding gene was expressed in Escherichia coli strain BL21 and the recombinant protein with His6-tag was purified to electrophoretic homogeneity. The purified enzyme exhibited optimal activity in the range of 35-40 °C and pH 8.0. EDTA, Mg(2+), Zn(2+), Ca(2+), Fe(2+), Fe(3+) and Mn(2+) stimulated hydrolytic activity, whereas Cu(2+), Co(2+) and Ni(2+) had inhibitory effect on nitrilase activity. Ag(+) ions showed a strong inhibitory effect on the recombinant nitrilase activity. This nitrilase was specific towards aliphatic, heterocyclic and aromatic nitriles. The kinetic parameters V(max) and K(m) for benzonitrile substrate were determined to be 14.6 μmol/min/mg protein and 1.55 mM, respectively. Homology modelling and molecular docking studies provided an insight into the substrate specificity and the proposed catalytic triad for recombinant nitrilase consisted of Glu-54, Lys-133 and Cys-175. This is the first report on the cloning and heterologous expression of nitrilase from Fusarium proliferatum.

Biotransformation of methylphenylacetonitriles by Brazilian marine fungal strain Aspergillus sydowii CBMAI 934: eco-friendly reactions

This study reports the biotransformation of methylphenylacetonitriles by Brazilian marine filamentous fungus Aspergillus sydowii CBMAI 934 under eco-friendly reaction conditions. The phenylacetonitrile 1, 2-methylphenylacetonitrile 2, 3-methylphenylacetonitrile 3, and 4-methylphenylacetonitrile 4 were quantitatively biotransformed into 2-hydroxyphenylacetic 1a, 2-methylphenylacetic acid 2a, 3-methylphenylacetic acid 3a, and 4-methylphenylacetic acid 4a by enzymatic processes using whole cell as biocatalyst. The marine fungus A. sydowii CBMAI 934 is thus a promising biocatalyst for the preparation of important carboxylic acids under mild conditions (pH 7.5 and 32 °C) from nitrile compounds.

Enhancing nitrilase production from Fusarium proliferatum using response surface methodology

The individual and interactive effects of three independent variables i.e. carbon source (glucose), nitrogen source (sodium nitrate) and inducer (ϵ-caprolactam) on nitrilase production from Fusarium proliferatum were investigated using design of experiments (DOE) methodology. Response surface methodology (RSM) was followed to generate the process model and to obtain the optimal conditions for maximum nitrilase production. Based on central composite design (CCD) a quadratic model was found to fit the experimental data (p<0.0001) and maximum activity of 59.0U/g biomass was predicted at glucose concentration (53.22 g/l), sodium nitrate (2.31 g/l) and ϵ-caprolactam (3.58 g/l). Validation experiments were carried out under the optimized conditions for verification of the model. The nitrilase activity of 58.3U/g biomass obtained experimentally correlated to the predicted activity which proves the authenticity of the model. Overall 2.24 fold increase in nitrilase activity was achieved as compared to the activity before optimization (26U/g biomass).