Cloning, expression, and characterization of a novel nitrilase, PaCNit, from Pannonibacter carbonis Q4.6

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.

Cloning and heterologous expression of Fusarium oxysporum nitrilase gene in Escherichia coli and evaluation in cyanide degradation

Cyanide is widely utilized in the extraction of precious metal extraction even though it has been deemed as the most toxic compound. Fusarium oxysporum has been shown to degrade cyanide through the activity of the Nitrilase enzyme. In this study, the coding sequence of nitrilase gene from F. oxysporum genomic DNA was optimized for cloning and expression in E. coli. The pUC57 containing synthetic optimized nitrilase gene was transferred into E. coli DH5α strain. This nitrilase gene was sub-cloned into pET26b (+) expression vector containing an in-built His-tag at the C-terminal end to facilitate its purification. The recombinant plasmid, pETAM1, was confirmed by PCR, digestion pattern, and sequencing. The recombinant protein was overproduced in E. coli BL21 (DE3). The results of the SDS-PAGE pattern and Western blot analysis confirmed the expression of the expected recombinant protein. For expression optimization of Nitrilase protein, M16 orthogonal experimental design of the Taguchi method was used. The effect of induction time, temperature and IPTG concentration were examined using four levels for each factors. Estimation of the amount of the expressed protein was calculated via densitometry on SDS-PAGE. The enzyme activity and expression in E. coli proved to be successful since there was ammonia production when potassium cyanide and acrylonitrile were used as substrates while the highest enzyme activity of 88% was expressed at 30 °C. The Km and Vm values of the expressed Nitrilase enzyme were determined to be 0.68 mM and 0.48 mM/min respectively.

Purification and Characterization of Nit phym , a Robust Thermostable Nitrilase From Paraburkholderia phymatum

Despite the success of some nitrilases in industrial applications, there is a constant demand to broaden the catalog of these hydrolases, especially robust ones with high operational stability. By using the criteria of thermoresistance to screen a collection of candidate enzymes heterologously expressed in Escherichia coli, the enzyme Nit _phym from the mesophilic organism Paraburkholderia phymatum was selected and further characterized. Its quick and efficient purification by heat treatment is of major interest for large-scale applications. The purified nitrilase displayed a high thermostability with 90% of remaining activity after 2 days at 30°C and a half-life of 18 h at 60°C, together with a broad pH range of 5.5-8.5. Its high resistance to various miscible cosolvents and tolerance to high substrate loadings enabled the quantitative conversion of 65.5 g⋅L^-1 of 3-phenylpropionitrile into 3-phenylpropionic acid at 50°C in 8 h at low enzyme loadings of 0.5 g⋅L^-1, with an isolated yield of 90%. This study highlights that thermophilic organisms are not the only source of industrially relevant thermostable enzymes and extends the scope of efficient nitrilases for the hydrolysis of a wide range of nitriles, especially trans-cinnamonitrile, terephthalonitrile, cyanopyridines, and 3-phenylpropionitrile.

Cloning and characterization of a novel thermostable amidase, Xam, from Xinfangfangia sp. DLY26

OBJECTIVE

Identification and characterization of a novel thermostable amidase (Xam) with wide pH tolerance and broad-spectrum substrate specificity.

RESULTS

Xam was identified from non-thermophilic Xinfangfangia sp. DLY26 and its acyl transfer activity was investigated. Recombinant Xam was optimally active at 60 °C and pH 9.0. The enzyme had a half life of 18 h at 55 °C and maintained more than 60 % of its maximum activity in the range of pH 3.0-11.0. Additionally, Xam exhibited broad substrate specificity towards aliphatic, aromatic, and heterocyclic amides.

CONCLUSIONS

These unique properties make Xam a promising biocatalyst for production of important hydroxamic acids at elevated temperatures.

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.

Thermoresponsive Gigaporous Microspheres Facilitate the Efficient Refolding of Recombinant Nitrilase Inclusion Bodies

In order to assist the refolding of recombinant nitrilase inclusion bodies, a series of thermoresponsive media were prepared by grafting poly(N-isopropylacrylamide-co-butyl-methacrylate) [P(NIPAM-co-BMA)] brushes onto PS microspheres with various particles and pore sizes via an atom transfer radical polymerization (ATRP) method. The effects of particle sizes, pore sizes, and brush grafting amounts of thermoresponsive microspheres on nitrilase refolding were investigated preliminarily. The results showed that the PS-P(NIPAM-co-BMA) microspheres with the medium particle size (74 μm), gigapore size (320 nm), and high grafting amount (35.6 mg/m²) were the most effective candidates. The final nitrilase activity yield could be up to 84.5% with a high initial protein concentration (1 mg/mL) at 30 °C, which was 52.5% higher than that of a simple dilution refolding method at the initial protein concentration (0.1 mg/mL). After the refolding process, the PS-P(NIPAM-co-BMA) microspheres can be easily separated by self-precipitation, and the activity yield of nitrilase still reached 74.5% after being reused for five batches. These results indicated that the thermoresponsive gigaporous medium was an ideal alternative as an artificial chaperone.