Volume XCIII, Number 5, October 26, 1973

WOS: 000346148200006Objective: The goal of this study was to determine the influence of various carbon sources on the citric and isocitric acid production by various Yarrowia lipolytica strains. Methods: The yeasts used in our study were first investigated for organic acid production using screening media. Then, the effect of several complex carbon sources on the citric and isocitric acid production of selected yeast strains was investigated. The amount of citric and isocitric acid production was determined via enzymatic reactions. Results: In this study, 22 Y. lipolytica strains were investigated for the organic acid production. Among these strains, 2 strains (TEM YL 3 and TEM YL 20) were found to be highest organic-acid producer. Taken all results together, the highest amounts of citric acid (66.2 g/L for TEM YL 3, 50.0 g/L for TEM YL 20) were observed in the production medium containing sunflower oil. Conclusion: Citric acid consumption, and thus, the need for it are constantly rising in our country, which imports citric acid. Therefore, in order to meet this need, further studies which will yield to the maximum citric acid production should be performed by utilizing waste carbon sources and by using new low- cost but high citric acid-producing strains.Scientific Research Unit of Ege UniversityEge University [12 FEN 006]This study was financially supported by Scientific Research Unit of Ege University (Project number: 12 FEN 006). This study was presented at the 21st National Biology Congress (3 - 7 September 2012) in Izmir, Turkey

Biotransformation of terpene and terpenoid derivatives by Aspergillus niger NRRL 326

WOS: 000521915000001Natural products are chemicals used in many industrial processes due to their various pharmacological or biological actions. Microorganisms can catalyze reactions that allow modification of structures of phytochemicals and organic compounds. Hereby, it is possible to obtain valuable products with regio- and stereo-selective reactions. The aim of the paper was to biotransform several terpenes and terpenoids including (-)-alpha-pinene, beta-ionone and isophorone by using A. niger NRRL 326 and to determine their biotransformation products and biological activities. According to the GC-MS analysis, the following compounds were obtained: (S)-(+)-carvone hydrate (4.28%) from (-)-alpha-pinene; 4-hydroxybetaionone (48.33%), 2-hydroxybetaionone (22.40%), alpha-ionone (1.29%) and dihydro-3-oxo-beta-ionol (1.11%) from beta-ionone; 4-hydroxyisophorone (55.54%), 3,3-dimethyl-5-oxo-cyclohexanecarboxaldehyde (1.87%), 4-ketoisophorone (1.22%) and dihydrooxoisophorone (0.59%) from isophorone. The biological activities of the extracts were found to be slightly higher than the control experiments. The findings obtained will contribute to the literature and A. niger NRRL 326 have the potential to become an important biotransformation agent.Scientific Research Unit of Giresun University [FEN-BAP-A-140316-60]The study was funded by the Scientific Research Unit of Giresun University (FEN-BAP-A-140316-60). Author is grateful to the Central Research Laboratory Research and Application Center (Giresun University) for providing facilities for the GC-MS analysis

Isolation and Characterization of Amylase Producing Yeasts and Improvement of Amylase Production

WOS: 000323180100016Objectives: Because most of the yeasts from nature are not harmful as compared to bacteria, interest in yeasts with potential use in biotechnological processes has increased in recent years. Therefore, in this study, we aimed to isolate and characterize amylase producing yeasts and investigate the effects of different parameters on the production of amylase. Methods: Five different sources were used for the isolation of the yeasts. For screening of the amylase production, the isolates were incubated in Amylase Activity Medium at 30 degrees C for 3 days. The amylase activity was determined by dinitrosalicylic acid method. Molecular characterization of the amylase producing yeasts was performed with restriction fragment length polymorphism (RFLP) of the 5.8S and 18S rRNA regions, and sequence analysis of D1/D2 domain of the 26S rRNA region. Results: In total, twenty five yeast isolates were obtained from five different sources. Following the incubation in medium containing starch for the screening of amylase production, it was found that 12 yeast isolates produce amylase, and among the isolates, three of them showed the highest amylase activity. The isolates (19-3, 19-6 and 19-7) having the highest activity were identified as S. fibuligera. The strains showed the highest amylase production at 30 degrees C and pH 5.5. Among additives, sodium chloride, polyethylene glycol, sodium dodecyl sulfate, Triton X-100 and Tween 80 stimulated the production of amylase. Other additives showed negative influence on the production of enzyme. Conclusion: The study revealed that favorable fermentation conditions and the selection of suitable growth parameters played key roles in the production of amylase by S. fibuligera.Scientific Research Unit of Ege UniversityEge University [12-FEN-020]This work was financially supported by the Scientific Research Unit of Ege University (Project Number: 12-FEN-020). We would like to extend our thanks to the Izmir Institute of Technology, Biotechnology and Bioengineering Central Research Laboratories (BIYOMER) for providing laboratory facilities for DNA sequencing studies

Isolation and characterization of yeasts associated with Turkish-style homemade dairy products and their potential as starter cultures

WOS: 000306317600008In 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.E.U. The Scientific Research Project (BAP) [2006-Fen-049]This study was supported by E.U. The Scientific Research Project (BAP) 2006-Fen-049

Determination and comparison of microbial loads in atmospheres of two hospitals in Izmir, Turkey

WOS: 000317708800019PubMed ID: 23540222Introduction and Objectives. Nosocomial infections, also known as hospital-acquired infections, has become one of the most important health problems in health care units worldwide. The presented study aims to determine the average amount of microorganism loads and to show that the atmospheres of the two hospitals can be a potential source regarding nosocomial infections. The effect of surface and floor disinfection processes in the two hospitals and the antibiotic susceptibility of the bacterial isolates were also evaluated. Materials and Methods. Microorganisms were isolated from air samples collected from different areas (patient wards, corridors, operating theatres and postoperative units) of the two hospitals in Izmir. Sampling was conducted between December 2006 March 2007. Results. During the 3-month sampling period, the average number of live microorganisms in the air samples collected from second-class environments in the hospital 1 and the hospital 2 was found to be 224.44 and 536.66 cfu/m(3), respectively. The average number of microorganisms in hospital 2 collected before the disinfection process was higher than those after the disinfection process. However, because of the closure of the air-conditioning system and the hepa filters after the disinfection process, this was reversed in hospital 1. In total, 54 and 42 isolates were obtained from hospital 1 and hospital 2, respectively. 49 isolates from hospital 1 and 35 isolates from hospital 2 were identified as Staphylococcus sp. The remaining isolates were identified as Aerococcus sp. and Entero coccus sp. Pseudomonas sp. was not determined in the air samples of the two hospitals. Conclusions. It was detected that the microbial loads in the atmospheres of the two hospitals studied varied greatly depending on the number of people in the environment. As the results indicate, the total number of microorganisms in the atmospheres of operating theatres in both hospitals does not pose a threat according to the Air Microbe Index.EU Scientific Research Project (BAP) [2007-FEN-031]The study was supported by the EU Scientific Research Project (BAP) 2007-FEN-031. The authors wish to thank Dr. Hayal BOYACIOGLU for the statistical analysis

Production and Optimization of Killer Toxin in Debaryomyces hansenii Strains

WOS: 000401007700006Postharvest 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 20 degrees C. 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