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    Genotypic discrimination of Aspergillus fumigatus strain from related species within section fumigati
    (Inst Agricultural Medicine, 2016) Giray, Betul; Kocaogut, Elif; Ucar, Fusun B.; Haliki-Uztan, Alev
    Introduction and objective. The aim was to make an exact diagnosis of 20 strains using molecular biological methods which were isolated from the atmosphere of the inpatient rooms in the Oncology and other departments of the Ege University Medical Faculty Hospital, and identified as Aspergillus fumigatus through phenotypic tests, and to determine their antibiotic susceptibility patterns. Materials and method. It was confirmed that the 20 phenotypically-identified A. fumigatus strains belonged to the section Fumigati after they were tested by the ITS-PCR method. Their sequence analysis was performed and the results sent to the NCBI GenBank, and their accession numbers were obtained. For their exact diagnosis at the species level, the beta-tub (beta-tubulin) and rodA (RodletA) genes were examined with the multiplex PCR. Anti-fungal susceptibility of the 20 strains was determined according to the M38-A2 standards. Results. As a result of ITS-PCR, it was confirmed that 19 of the 20 strains identified as A. fumigatus through the phenotypic methods belonged to the section Fumigati. However, after the detection of beta-tub and rodA genes, all 20 strains were identified as A. fumigatus. Conclusion. Although the results of the phenotypic and molecular biological tests applied to filamentous fungi do not often overlap, in this study, the results obtained from the molecular analysis confirmed the results of the phenotypic tests. However, 1 of the 20 strains phenotypically-identified as A. fumigatus was identified as Penicillium spp. as a result of ITS-PCR and sequence analysis. On the other hand, the profile obtained from beta-tub and rodA tests indicated that the strain was A. fumigatus. Based on these results, this strain is thought to belong to the Aspergilloides genus which has the features of both genera.
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    Isolation and characterization of cheese spoiler yeast isolated from Turkish white cheeses
    (Springer, 2009) Yalcin, H. Tansel; Ucar, Fusun B.
    Ninety-two yeast strains causing spoilage on different kinds of Turkish white cheeses were isolated and identified on the basis of their physiological and morphological properties. The identified isolates represented 12 species belonging to 8 genera. The most prevalent isolates belonged to the species Debaryomyces hansenii (32.6%), Kluyveromyces marxianus (18.5%) and Yarrowia lipolytica (17.4%). Other genera encountered were Pichia, Torulaspora, Candida, Williopsis, and Galactomyces. They were genotypically characterized with PCR amplification of the species-specific internally transcribed spacer (ITS) of 5.8S ribosomal DNA (ITS-PCR). ITS-PCR of 15 strains of Y. lipolytica, 15 strains of K. marxianus and 25 strains of D. hansenii resulted in single fragments of 360, 740 and 640 bp, respectively. Proteolytic and lipolytic activity within yeast strains isolated from cheese was observed. Lipolytic and proteolytic organisms play an important role in the maturation of cheese and in the spoilage of dairy products. Usage of identification systems based on biochemical and physiological characteristics takes longer time and often results in misidentifications. In this study, false identification of 5 strains of D. hansenii, 2 strains of K. marxianus, 1 strain of Y. lipolytica, 1 strain of Torulaspora delbrueckii, 1 strain of Pichia anamola and 1 strain of Candida sake by using conventional methods confirmed the mentioned statement above. As a consequence, ITS-PCR was found to be more rapid, reliable, easy to perform and cost effective than biochemical approaches.
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    Isolation and characterization of yeasts associated with Turkish-style homemade dairy products and their potential as starter cultures
    (Academic Journals, 2012) Corbaci, Cengiz; Ucar, Fusun B.; Yalcin, H. Tansel
    In this research, 56 yeast strains were isolated from different homemade dairy products in Turkey. Traditional and genotypic methods were used for the characterization of the yeast strains. Debaryomyces hansenii (82%) was the dominant species in all the studied samples and only this species was found in at least one sample from all the studied samples. The other isolates belonged to the species Candida haemulonii, Candida membranifaciens, Candida tropicalis, Candida zeylanoides, Kluyveromyves marxianus, Pichia anomala and Pichia guilliermondii. In the present study, the following properties were studied: lipolytic and proteolytic activities, the ability to grow at different temperatures, different values of pH, different concentrations of salt, and to assimilate and or ferment compounds like citrate, galactose, glucose, lactate, lactose. In conclusion, we found that TEM 16 and TEM 17 strains identifed as D. hansenii in this study have the potential to be used in the production of cheese in Turkey.
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    Molecular characterization and lipase profiling of the yeasts isolated from environments contaminated with petroleum
    (Wiley-Blackwell, 2014) Yalcin, H. Tansel; Corbaci, Cengiz; Ucar, Fusun B.
    In the present study, 120 yeast isolates from different sources (active sludge, soil, and wastewater samples obtained from petroleum refinery and soil contaminated by petroleum) were obtained. The yeast isolates were screened for lipase production and twelve of the isolates (D3, D17, D24, D27, D30, D38, D40, D42, D44, D46, D56, and D57) exhibited lipase activity. Molecular characterization of the yeasts showing the lipase production was performed with RFLP of ITS15.8S- ITS2 and 18S rRNA and sequence analysis of D1/D2 domain of 26S rRNA. The 26S rRNA sequencing revealed that four new strains, D38, D40, D44 and D57 identified as Rhodotorula slooffiae, Candida davisiana, Cryptococcus diffluens, and Cryptococcus uzbekistanensis, respectively, are lipase producing yeast species. This study is the first report showed lipase production by these species. The other lipase producing strains identified as Candida parapsilosis (D3), Rhodotorula muciloginosa (D17 and D42), Cryptococcus albidus (D24, D27, D30, and D56), and Wickerhamomyces anomalus (D46).
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    Purification, characterization and in vivo biocontrol efficiency of killer toxins from Debaryomyces hansenii strains
    (Elsevier Science Bv, 2018) Corbaci, Cengiz; Ucar, Fusun B.
    Nowadays, the biological control of various yeast and mold pathogens that cause diseases in humans, animals, and plants is an increasing of interest. The discovery of novel agents allows prevention of infectious diseases and post-harvest losses reported every year. In the study, we aimed to investigate the production, purification, and characterization as well as in vivo biocontrol efficiency of killer toxins produced by Debaryomyces hansenii strains TEM8 and TEM17. The molecular mass of the killer toxins was 31.5 kDa and they showed high stability at pHs between 2.5 and 5.5 and up to 37 degrees C. Their internal amino acid sequences matched the DEHA2G18766g (CAG90862.1) from D. hansenii CBS767, which is similar to Saccharomyces cerevisiae YGR282C BGL2 endo-beta-1,3-glucanase. The yeasts and their purified killer toxins significantly inhibited the growth of plant pathogenic fungi Alternaria brassicicola, Alternaria citri, Aspergillus niger and Rhizopus stolonifer in fruits. The findings of this paper have recommended these yeast strains and their toxins as effective biocontrol agents against fungi that cause post-harvest diseases. (C) 2018 Published by Elsevier B.V.