Enantioselective biocatalytic hydrolysis of (R,S)-mandelonitrile for production of (R)-(−)-mandelic acid by a newly isolated mutant strain

Abstract

(R)-(-)-Mandelic acid (R-MA) is an important intermediate with broad uses. Recently, R-MA production using nitrilase has been gaining more and more attention due to its higher productivity and enantioselectivity. In this work, a new bacterium WT10, which exhibited favorable nitrilase activity and excellent enantioselectivity for production of R-MA by enantioselective biocatalytic hydrolysis of (R,S)-mandelonitrile, was isolated and identified as a strain of Alcaligenes faecalis. In order to improve its nitrilase activity for industrial application, the wild-type strain WT10 was further subjected to mutagenesis using a combined LiCl-ultraviolet irradiation and low energy N(+) ion beams implantation technique. A valuable mutant strain A. faecalis ZJUTB10 was obtained. The nitrilase specific activity of the mutant strain was greatly improved up to 350.8 U g(-1), in comparison with wild-type strain WT10 of 53.09 U g(-1). The reaction conditions for R-MA production by mutant strain A. faecalis ZJUTB10 were also optimized. Nitrilase activity in mutant strain showed a broad pH optimum at pH 7.7-8.5. The optimal temperature was 35°C. The highest production rate reached 9.3 mmol h(-1) g(-1). The results showed that mutant strain A. faecalis ZJUTB10 was a new candidate for efficient R-MA production from (R,S)-mandelonitrile and could potentially be used in industrial production.

Screening, cultivation, and biocatalytic performance of Rhodococcus boritolerans FW815 with strong 2,2-dimethylcyclopropanecarbonitrile hydratase activity

“…In recent years, we have conducted extensive studies on the bioresolution of enantiopure S-DMCPCA with Delftia tsuruhatensis ZJB-05174, Brevibacterium epidermidis ZJB-07021 [11,23,24,[27][28][29]. To make these enzymatic processes more competitive, economic, also inspired by our vast experiences in developing biocatalytic processes with nitrile-converting enzymes [10,21,22,25,26], an attempt to explore a twostep enzymatic process for S-DMCPCA by introducing 2,2-dimethylcyclopropanecarbonitrile (DMCPCN) hydration with NHase was proposed ( Fig. 1).…”

“…As a group of industrial biocatalyst, NHases are at the center of large-scale production of a variety of valuable amides, including acrylamide and niacinamide. During the past 20 years, nitrile hydration and hydrolysis catalyzed by nitrile-converting enzymes has been regarded as a powerful tool in organic synthesis for preparation of some valuable amides and acids [1,15,19,20,25,26]. Since biocatalysis provides an efficient, environmentally benign strategy for creating optically pure chemicals and operates under mild conditions [1,4,14], bioconversions of S-DMCPCA and S-2,2-dimethylcyclopropanecarboxylic acid are attractive.…”

Stereo-selective conversion of mandelonitrile to (R)-(−)-mandelic acid using immobilized cells of recombinant Escherichia coli

“…Its derivatives are used also as chiral resolving agents (Kinbara et al 1996; Xue et al 2011). Polymers of mandelic acid have been developed into antimicrobial contraceptives for vaginal prophylaxis (Zaneveld et al 2002).…”

“…Nitrilase-mediated production of ( R )-(−)-mandelic acid has significant advantage over chemical methods of production; it offers excellent enatioselectivity and above all possibility of carrying out dynamic kinetic resolution which provides 100 % theoretical yield of the product (Yamamoto et al 1991; Banerjee et al 2006; Singh et al 2005; Xue et al 2011) (Fig. 1).…”

Improvement of polysaccharide and triterpenoid production ofGanoderma lucidumthrough mutagenesis of protoplasts

“…Alcaligenes faecalis WT10 was subjected to mutagenesis by using a combined LiClÀUV irradiation and low energy N C -beam implantation technique to improve its nitrilase activity for industrial applications. [21] Peng et al [22] used LiCl to enhance the degradation of phenol by Rhodococcus ruber SD3. Wang et al [23] successfully performed a protoplast mutation of the endophytic fungus Tubercularia sp.…”