During recent years, a new disease of Siberian fir (A. sibirica) emerged in Central Siberia, exhibiting symptoms of stem/branch deformation, cambium necrosis, and dieback of branches and twigs, the causal agent remaining unknown. The aim was to identify agent of the disease and to investigate its pathogenicity to A. sibirica and Norway spruce (Picea abies). Symptomatic tissues of fir were subjected to pure culture isolation of anticipated pathogen(s). Obtained isolates were subjected to molecular identification, phylogenetic analyses, and pathogenicity tests with A. sibirica saplings, and seeds and seedlings of A. sibirica and P. abies. The study demonstrated that, (i) most commonly isolated fungus from canker wounds of A. sibirica exhibited Acremonium-like anamorphs; (ii) phylogeny demonstrated that investigated fungi belong to genus Corinectria, but are genetically well separated from other worldwide known Corinectria spp.; (iii) one species of isolated fungi has the capacity to cause the disease and kill A. sibirica saplings and seedlings, but also seedlings of P. abies. Guidelines for future research were defined in order to generate needed information on species description, its origin and ecology, and estimation of potential risks upon the eventual invasion of the pathogen to new geographic areas, in particular of Europe.
- MeSH
- fylogeneze MeSH
- jedle mikrobiologie MeSH
- mikroskopie elektronová rastrovací MeSH
- Nectria genetika patogenita ultrastruktura MeSH
- nemoci rostlin mikrobiologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Sibiř MeSH
The application of arylacetonitrilases from filamentous fungi to the hydrolysis of high concentrations of (R,S)-mandelonitrile (100-500 mM) was demonstrated for the first time. Escherichia coli strains expressing the corresponding genes were used as whole-cell catalysts. Nitrilases from Aspergillus niger, Neurospora crassa, Nectria haematococca, and Arthroderma benhamiae (enzymes NitAn, NitNc, NitNh, and NitAb, respectively) exhibited different degrees of enantio- and chemoselectivity (amide formation). Their enantio- and chemoselectivity was increased by increasing pH (from 8 to 9-10) and adding 4-10% (v/v) toluene as the cosolvent. NitAn and NitNc were able to convert an up to 500 mM substrate in batch mode. NitAn formed a very low amount of the by-product, amide (<1% of the total product). This enzyme produced up to >70 g/L of (R)-mandelic acid (e.e. 94.5-95.6%) in batch or fed-batch mode. Its volumetric productivities were the highest in batch mode [571 ± 32 g/(L d)] and its catalyst productivities in fed-batch mode (39.9 ± 2.5 g/g of dcw). NitAb hydrolyzed both enantiomers of 100 mM (R,S)-mandelonitrile at pH 5.0 and is therefore promising for the enantioretentive transformation of (S)-mandelonitrile. Sequence analysis suggested that fungal arylacetonitrilases with similar properties (enantioselectivity, chemoselectivity) were clustered together.
- MeSH
- aminohydrolasy chemie genetika metabolismus MeSH
- Arthrodermataceae enzymologie MeSH
- Aspergillus niger enzymologie MeSH
- druhová specificita MeSH
- fungální proteiny chemie genetika metabolismus MeSH
- fylogeneze MeSH
- koncentrace vodíkových iontů MeSH
- kyseliny mandlové metabolismus MeSH
- Nectria enzymologie MeSH
- Neurospora crassa enzymologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- aminohydrolasy MeSH
- fungální proteiny MeSH
- kyseliny mandlové MeSH
- mandelic acid MeSH Prohlížeč
