Füsun Uçar

Isolation and characterization of cheese spoiler yeast isolated from Turkish white cheeses

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 speciesDebaryomyces hansenii (32.6%),Kluyveromyces marxianus (18.5%) andYarrowia lipolytica (17.4%). Other genera encountered werePichia, 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 ofY. Lipolytica, 15 strains ofK. Marxianus and 25 strains ofD. 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 ofD. Hansenii, 2 strains ofK. Marxianus, 1 strain ofY. Lipolytica, 1 strain ofTorulaspora delbrüeckii, 1 strain ofPichia anamola and 1 strain ofCandida 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.

Molecular characterization and lipase profiling of the yeasts isolated from environments contaminated with petroleum

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 ITS1‐5.8S‐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).

Antimicrobial and Antifungal Activities of Three New Triterpenoid Glycosides

The antimicrobial and antifungal activities of the MeOH extract of the flowers of Cephalaria transsylvanica and three triterpenic acid glycosides, transsylvanoside A–C from the flowers of the plant were assayed using an agar‐disc diffusion method. The results showed that both the MeOH extract and the glycosides possess antimicrobial and antifungal activities against Staphylococcus aureus, Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa, Corynebacterium xerosis, Klebsiella pneumoniae, Candida utilis, Kluyveromyces fragilis, Aspergillus oryzae and Aspergillus flavus respectively.

Screening and regulation of alkaline extracellular protease and ribonuclease production of Yarrowia lipolytica strains isolated and identified from different cheeses in Turkey

In this research, 43 yeast strains were isolated from different types of cheese in Turkey and these isolates were identified with both phenotypic tests and genotypic tests with 5.8S ITS-PCR. Also, the sequence of PCR fragments obtained from ITS-PCR was analyzed by DNA sequencing. In the results of the phenotypic tests, 9 of 43 isolates were identified as Yarrowia lipolytica. After the phenotypic identification, all the isolates were identified with ITS-PCR and 13 were identified as Y. lipolytica. Yarrowia lipolytica secretes several hydrolytic enzymes including alkaline and acid proteases, lipases, a ribonuclease, and phosphotases. In this paper, the effect of carbon and nitrogen sources and pH on production of AEP and RNase were examined for our identified strains of Y. lipolytica. The best production of AEP were found in skim milk medium with pH 7.0 by TEM YL 5 and Y. lipolytica CBS 6124 type strain. An extra carbon source (glucose) reduced AEP production at all the pH studied. Glutamine which is a nitrogen source did not affect AEP production. In contrast to AEP production, glucose increased RNase production at all the pH studied.

Production and Optimization of Killer Toxin in Debaryomyces hansenii Strains

Postharvest diseases of fruits and vegetables result in critical losses of production in worldwide. The losses often are caused by fungi and nowadays, most fungal pathogens are controlled by several strategies such as the use of fungicides. However, most of the fungicides are chemical-based compounds and are dangerous to human health and the nature. Therefore, the discovery of healthy and reliable strategies is crucial to control of fungal pathogens. In the paper, it was aimed to evaluate and characterize yeast isolates previously isolated from dairy products for the production of killer toxin. A total of 18 yeasts have been found to produce antagonistic behavior against susceptible fungal species. All of the yeasts expressing killer character were characterized by using several molecular techniques, and isolates TEM8 and 17 identified as D. hansenii have showed the strongest antifungal activities. Improvement of killer toxin production by the yeasts also has been studied, and the highest production was found in YMB medium containing NaCl (6%) and DMSO (1000 ppm) at pH 4.0 and 20oC. The killer characters of these yeasts have indicated the potential use of the yeasts as antagonists for the control of postharvest diseases in agricultural industries.

Genotypic analysis of Escherichia coli strains that cause urosepsis in the Aegean region.

BACKGROUND/AIM The aim of this study was to characterize strains genotypically, to determine their phylogenetic relationships, to investigate the presence of the papG gene, and to compare their antibiotic susceptibility test results. MATERIALS AND METHODS Seventy pathogenic E. coli strains were isolated from both urine and blood cultures of patients with the preliminary diagnosis of urosepsis who were referred to the Ege University Faculty of Medicine, Bacteriology Laboratory of Medical Microbiology Department in İzmir. All of these strains were examined for the papG gene and phylogenetic groups with the multiplex polymerase chain reaction technique. Pulsed-field gel electrophoresis and multilocus sequence typing (MLST) were used for epidemiologic analysis. RESULTS Phylogenetically, it was found that 16 belonged to group B2, 31 belonged to group D, 15 belonged to group A, and 7 belonged to group B1. One strain was not identified as belonging to a group. papG genes were found in 26 of 70 E. coli strains. Thirty urosepsis pathogenic E. coli strains were analyzed with MLST. Twenty-two strains were identified as new STs. CONCLUSION These findings are extremely important for Turkey and these new 22 strains should be investigated in more detail because they are new and have the potential to lead to infections.

Screening and molecular characterization of polycyclic aromatic hydrocarbons degrading yeasts / Polisiklik aromatik hidrokarbonları parçalayan mayaların taranması ve moleküler karakterizasyonu

Abstract Objective: Disasters such as leakages and accidental falls are the main causes of environmental pollution by the petroleum industry product. Since no commercial yeast strain with biodegradation capacity is available, we aimed to isolate and characterize hydrocarbon degrading yeasts. Methods: Yeast isolates used in the study were isolated from samples of wastewater, active sludge and crude oil, which was obtained from a petroleum refinery as well as from soil samples, which were contaminated with crude oil. Yeast isolates used in the study were isolated from wastewater, active sludge and petroleum samples obtained from petroleum refinery and soil samples contaminated with petroleum. Degradation of naphthalene, phenanthrene, pyrene and crude petroleum by yeasts were determined using a microtiter plate-based method. Molecular characterization was achieved by performing a sequence analysis of the ITS1-5.8S rRNA-ITS2 and 26S rRNA regions. Results: In total, 100 yeast isolates were obtained from four different samples. Following the incubation in media containing different polycyclic aromatic hydrocarbon compounds (naphthalene, phenanthrene, pyrene) and crude petroleum, 12 yeast isolates were detected to degrade more than one polyaromatic hydrocarbon. Sequence analyses of rRNA regions revealed that the identified yeasts represented 10 species belonging to 6 genera. The isolates were identified as Candida parasilopsis, Candida sinolaborantium, Cryptococcus albidus, Cryptococcus diffluens, Cryptococcus uzbekistanensis, Pichia kudriavzevii, Rhodosporidium diobovatum, Rhodotorula glutinis, Rhodotorula muciloginosa and Saccharomyces cerevisiae. Conclusion: Yeast strains that are capable of degrading more than one polycyclic aromatic hydrocarbon compound have the potential of being utilized in future research. Özet Amaç: Petrol endüstrisi ürünleri ile oluşturulan sızıntılar ve kazalar gibi felaketler, çevresel kirliliğe neden olan ana faktörlerdir. Mevcut durumda, biyo-parçalama kapasitesine sahip ticari bir maya suşu bulunmamaktadır. Bu yüzden, geniş hidrokarbon parçalama aktivitesine sahip maya suşlarının saptanması, bu kirliliklerin azaltılmasında önemli bir rol oynamaktadır. Belirtilen bu sebeple, çalışmamızda, hidrokarbon parçalayan mayaların izolasyonu ve karakterizasyonu amaçlanmıştır. Metod: Çalışmada kullanılan maya izolatları, petrol rafinerisinden alınmış atık su, aktif çamur ve petrol örnekleri ve petrol ile kontamine olmuş toprak örneklerinden izole edilmiştir. Naftalen, fenantren, piren ve ham petrolün mayalar tarafından parçalanması, mikrotitre plaka yöntemi kullanılarak saptanmıştır. Mayaların moleküler karakterizasyonu, ITS1-5.8S rRNA-ITS2 ve 26S rRNA bölgelerinin dizi analizi ile gerçekleştirilmiştir. Bulgular: Toplamda, dört farklı örnekten 100 maya izolatı elde edilmiştir. Farklı polisiklik aromatik hidrokarbon bileşikleri (naftalen, fenantren, piren) ve ham petrol içeren ortamlarda inkübasyondan sonra, 12 maya izolatının birden fazla poliaromatik hidrokarbonu parçalayabildiği bulunmuştur. rRNA bölgelerinin dizi analizi, tanılanan mayaların 6 genusa dahil olan 10 türü temsil ettiklerini göstermiştir. İzolatlar, Candida parasilopsis, Candida sinolaborantium, Cryptococcus albidus, Cryptococcus diffluens, Cryptococcus uzbekistanensis, Pichia kudriavzevii, Rhodosporidium diobovatum, Rhodotorula glutinis, Rhodotorula muciloginosa ve Saccharomyces cerevisiae olarak tanılanmıştır. Sonuç: Birden fazla polisiklik aromatik hidrokarbon bileşiğini parçalayan maya suşları, ileriki araştırmalarda kullanım potansiyeline sahiptir

Purification, characterization and in vivo biocontrol efficiency of killer toxins from Debaryomyces hansenii strains

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 °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.

Genotypic discrimination of Aspergillus fumigatus strain from related species within section fumigati.

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 β-tub (β-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 β-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 β-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.