Journal of Microbiology

Research Support, Non-U.S. Gov'ts

NOTE] Antifungal Activity of Extracellular Hydrolases Produced by Autolysing Aspergillus nidulans Cultures: Melinda Szilágyi , Fruzsina Anton , Katalin Forgács , Jae-Hyuk Yu , István Pócsi , Tamás Emri; J. Microbiol. 2012;50(5):849-854. Published online November 4, 2012; DOI: https://doi.org/10.1007/s12275-012-2001-0

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Abstract: Carbon-starving Aspergillus nidulans cultures produce high activities of versatile hydrolytic enzymes and, among these, ChiB endochitinase and EngA β-1,3-endoglucanase showed significant antifungal activity against various fungal species. Double deletion of engA and chiB diminished the antifungal activity of the fermentation broths and increased conidiogenesis and long-term viability of A. nidulans, but decreased the growth rate on culture media containing weak carbon sources. Production of ChiB and EngA can influence fungal communities either directly due to their antifungal properties or indirectly through their effects on vegetative growth. Our data suggest saprophytic fungi as promising future candidates to develop novel biocontrol technologies.

Predicting the Chemical Composition and Structure of Aspergillus nidulans Hyphal Wall Surface by Atomic Force Microscopy: Hyun-uk Lee , Jong Bae Park , Haeseong Lee , Keon-Sang Chae , Dong-Min Han , Kwang-Yeop Jahng; J. Microbiol. 2010;48(2):243-248. Published online May 1, 2010; DOI: https://doi.org/10.1007/s12275-010-8094-4

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Abstract: In fungi, cell wall plays an important role in growth and development. Major macromolecular constituents of the aspergilli cell wall are glucan, chitin, and protein. We examined the chemical composition and structure of the Aspergillus nidulans hyphal wall surface by an atomic force microscope (AFM). To determine the composition of the cell wall surface, the adhesion forces of commercially available β-glucan, chitin, and various proteins were compared to those of corresponding fractions prepared from the hyphal wall. In both setups, the adhesion forces of β-glucan, chitin, and protein were 25-50, 1000-3000, and 125-300 nN, respectively. Adhesion force analysis demonstrated that the cell surface of the apical tip region might contain primarily chitin and β-glucan and relatively a little protein. This analysis also showed the chemical composition of the hyphal surface of the mid-region would be different from that of the apical region. Morphological images obtained by the tapping mode of AFM revealed that the hyphal tip surface has moderate roughness.

Differential Expression of citA Gene Encoding the Mitochondrial Citrate Synthase of Aspergillus nidulans in Response to Developmental Status and Carbon Sources: In Sook Min , Ji Young Bang , Soon Won Seo , Cheong Ho Lee , Pil Jae Maeng; J. Microbiol. 2010;48(2):188-198. Published online May 1, 2010; DOI: https://doi.org/10.1007/s12275-010-0096-8

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Abstract: As an extension of our previous studies on the mitochondrial citrate synthase of Aspergillus nidulans and cloning of its coding gene (citA), we analyzed differential expression of citA in response to the progress of development and change of carbon source. The cDNA consisted of 1,700 nucleotides and was predicted to encode a 474-amino acid protein. By comparing the cDNA sequence with the corresponding genomic sequence, we confirmed that citA gene contains 7 introns and that its transcription starts at position -26 (26-nucleotide upstream from the initiation codon). Four putative CreA binding motifs and three putative stress-response elements (STREs) were found within the 1.45-kb citA promoter region. The mode of citA expression was examined by both Northern blot and confocal microscopy using green fluorescent protein (sGFP) as a vital reporter. During vegetative growth and asexual development, the expression of citA was ubiqiutous throughout the whole fungal body including mycelia and conidiophores. During sexual development, the expression of citA was quite strong in cleistothecial shells, but significantly weak in the content of cleistothecia including ascospores. Acetate showed a strong inductive effect on citA expression, which is subjected to carbon catabolite repression (CCR) caused by glucose. The recombinant fusion protein CitA40::sGFP (sGFP containing the 40-amino acid N-terminal segment of CitA) was localized into mitochondria, which supports that a mitochondrial targeting signal is included within the 40-amino acid N-terminal segment of CitA.

Quantitative analysis of gene expression pattern in aspergillus nidulans mycelia by sequencing of 3'-directed cDNA clones: Park, Yoon Dong , Lee, Dong Whan , Lee, Seog Jae , Kim, Jong Hwa , Chae, Keon Sang; J. Microbiol. 1996;34(1):23-29.

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Abstract: Since sequencing of randomly selected cDNA clones has been known to be a powerful approach to obtain information on gene expression pattern in specific cells or tissues, we have analyzed a 3'-directed cDNA library of vegetative mycelia of A. nidulans by single-pass sequencing of hundreds of randomly selected clones. Sequencing of 292 cDNA clones yielded 209 gene signatures (GSs) probably representing highly or lesser expressed genes in the vegetative mycelia. Among the 209 GSs, 25 (79 cDNA clones) appeared more than once and 184 only once. One GS appeared at a highest frequency of 6 times, 2 GSs5 times, 4 GSs 4 times, a GSs 3 times and 16 GSs twice. About 6.6% GSs comprizing of 13 GSs showed alternative polyadenylation. Among 23 redundant GSs, three were common in both mycelia and sexual organs, and 22 were probably mycelia-specific. Out of 209 GSs, 36 were identified in GenBank showing of 70% or greater similaritis. Only six GSs were for A. nidulans genes, and 13 GSs were of DNA or genes encoding cytoplasmic or organellar proteins. This pattern is similar to those in the human HepG2 cell line and in human colonic mucosa, although very few genes for nuclear proteins and for protein synthesis were in A. nidulans.

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