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benzoic acid under the reaction conditions adopted.
Although it is known that the activity of nitrile
hydratase/amidase systems can be selectively con-
trolled through the appropriate choice of operational
conditions, such as in Microbacterium imperiale
(Cantarella et al. 2006), current evidence suggests
that Aspergillus sp. PTCC 5266 contains a nitrilase
only. Amide production using nitrilase on substrates
with electron-withdrawing groups is a common
characteristic and the pH profiles for all of the sub-
strates were similar. Furthermore, nitrile hydratases
have hitherto not been detected in fungi.
Our biocatalyst produced a high acid/amide
ratio for 4-nitrophenylacetonitrile, 2-chlorobenzo-
nitrile and 3-chlorobenzonitrile, and only carboxy-
lic acid for the other substrates, so it may be useful
for synthesis of carboxylic acids. The formation of
amides may complicate the use of nitrilases for
carboxylic acid production. However, the benefit of
nitrilases in comparison with nitrile hydratases
is their higher stability and enantioselectivity
(Martínková & Krˇen, 2010).
Bunch AW. 1998. Biotransformation of nitriles by rhodococci.
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Cantarella M, Cantarella L, Gallifuoco A, Spera A. 2006. Use of
a UF-membrane reactor for controlling selectively the nitrile
hydratase – amidase system in Microbacterium imperiale CBS
498-74 resting cells. Case study: benzonitrile conversion.
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Kaplan O, Nikolaou K, Pišvejcová A, Martínková L. 2006a.
Hydrolysis of nitriles and amides by filamentous fungi. Enzyme
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Kaplan O,Vejvoda V, Plíhal O, Pompach P, Kavan D, Bojarová P,
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Conclusions
Aspergillus sp. PTCC 5266 transforms nitriles, espe-
cially aromatic nitriles, probably via a nitrilase path-
way. The product of the biotransformation of most
substrates was the pure carboxylic acid, but some
nitriles gave a low ratio of the corresponding amide.
The Aspergillus sp. PTCC 5266 nitrile-hydrolyzing
activity exhibited significant stability over prolonged
reaction times compared with previously described
fungal nitrile-hydrolyzing microorganisms. Also it
accepts both aliphatic and aromatic nitriles and
could be used for producing carboxylic acids with
relatively high yields.
Kato Y, Tsuda T, Asano Y. 1999. Nitrile hydratase involved
in aldoxime metabolism from Rhodococcus sp. strain YH3-3
purification and characterization. Eur
662–670.
J Biochem 263:
Declaration of interest: This work was supported
by the Research Council of Shahid Beheshti Uni-
versity Tehran, Iran, for which authors are grateful.
The authors report no conflicts of interest. The
authors alone are responsible for the content and
writing of the paper.
Malandra A, Cantarella M, Kaplan O, Vejvoda V, Uhnáková B,
Šteˇpánková B, Kubácˇ D, Martínková L. 2009. Continuous
hydrolysis of 4-cyanopyridine by nitrilases from Fusarium solani
O1 and Aspergillus niger K10. Appl Microbiol Biotechnol
85:277–284.
Martínková L, Krˇen V. 2010. Biotransformations with nitrilases.
Curr Opin Chem Biol 14:130–137.
Martínková L, Mylerová V. 2003. Synthetic applications of
nitrile-converting enzymes. Curr Org Chem 7:1279–1295.
Martínková L, Vejvoda V, Krˇen V. 2008. Selection and screening
for enzymes of nitrile metabolism. J Biotechnol 133:318–326
Martínková, L, Uhnáková B, Pátek M, Nešvera J, Krˇen V. 2009a.
Biodegradation potential of the genus Rhodococcus. Environ Int
35:162–177.
Martínková L,VejvodaV, Kaplan O, Kubácˇ D, Malandra A, Can-
tarella M, Bezouška K Krˇen V. 2009b. Fungal nitrilases as bio-
catalysts: recent developments. Biotechnol Adv 27:661–670.
O’Reilly C,Turner PD. 2003.The nitrilase family of CN hydrolyzing
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