SIM
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Stud Mycol 61(1): 165-174 2008
DOI: 10.3114/sim.2008.61.17
Copyright © 2008 CBS Fungal Biodiversity Centre
This Article
Free via Open Access: OA
Right arrow OA Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Rustler, S.
Right arrow Articles by Stolz, A.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Rustler, S.
Right arrow Articles by Stolz, A.

You are free to share - to copy, distribute and transmit the work, under the following conditions:

Attribution:  You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work).

Non-commercial:  You may not use this work for commercial purposes.

No derivative works:  You may not alter, transform, or build upon this work.

For any reuse or distribution, you must make clear to others the license terms of this work, which can be found at http://creativecommons.org/licenses/by-nc-nd/3.0/legalcode. Any of the above conditions can be waived if you get permission from the copyright holder. Nothing in this license impairs or restricts the author's moral rights.

Characterisation of the substrate specificity of the nitrile hydrolyzing system of the acidotolerant black yeast Exophiala oligosperma R1

S. Rustler1, A. Chmura2, R.A. Sheldon2 and A. Stolz1

1 Institut für Mikrobiologie, Universität Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
2 Laboratory of Biocatalysis and Organic Chemistry, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands

Correspondence: Andreas Stolz. Andreas.Stolz{at}imb.uni-stuttgart.de

The `black yeast' Exophiala oligosperma R1 can utilise various organic nitriles under acidic conditions as nitrogen sources. The induction of a phenylacetonitrile converting activity was optimised by growing the strain in the presence of different nitriles and /or complex or inorganic nitrogen sources. The highest nitrile hydrolysing activity was observed with cells grown with 2-cyanopyridine and NaNO3. The cells metabolised the inducer and grew with 2-cyanopyridine as sole source of nitrogen. Cell extracts converted various (substituted) benzonitriles and phenylacetonitriles. They usually converted the isomers carrying a substituent in the meta-position with higher relative activities than the corresponding para- or ortho-substituted isomers. Aliphatic substrates such as acrylonitrile and 2-hydroxy-3-butenenitrile were also hydrolysed. The highest specific activity was detected with 4-cyanopyridine. Most nitriles were almost exclusively converted to the corresponding acids and no or only low amounts of the corresponding amides were formed. The cells hydrolysed amides only with extremely low activities. It was therefore concluded that the cells harboured a nitrilase activity. The specific activities of whole cells and cell extracts were compared for different nitriles and evidence obtained for limitation in the substrate-uptake by whole cells. The conversion of 2-hydroxy-3-butenenitrile to 2-hydroxy-3-butenoic acid at pH 4 demonstrated the unique ability of cells of E. oligosperma R1 to hydrolyse aliphatic {alpha}-hydroxynitriles under acidic conditions. The organism could grow with phenylacetonitrile as sole source of carbon, energy and nitrogen. The degradation of phenylacetonitrile presumably proceeds via phenylacetic acid, 2-hydroxyphenylacetic acid, 2,5-dihydroxyphenylacetic acid (homogentisate), maleylacetoacetate and fumarylacetoacetate.

Keywords Acidotolerance / biotransformation / black yeasts / Exophiala / homogentisate pathway / induction / nitrilase






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2008 by the CBS Fungal Biodiversity Centre.