Duygu Kışla

Isolation and Identification of a Paenibacillus polymyxa Strain That Coproduces a Novel Lantibiotic and Polymyxin

ABSTRACT A new bacterial strain, displaying potent antimicrobial properties against gram-negative and gram-positive pathogenic bacteria, was isolated from food. Based on its phenotypical and biochemical properties as well as its 16S rRNA gene sequence, the bacterium was identified as Paenibacillus polymyxa and it was designated as strain OSY-DF. The antimicrobials produced by this strain were isolated from the fermentation broth and subsequently analyzed by liquid chromatography-mass spectrometry. Two antimicrobials were found: a known antibiotic, polymyxin E1, which is active against gram-negative bacteria, and an unknown 2,983-Da compound showing activity against gram-positive bacteria. The latter was purified to homogeneity, and its antimicrobial potency and proteinaceous nature were confirmed. The antimicrobial peptide, designated paenibacillin, is active against a broad range of food-borne pathogenic and spoilage bacteria, including Bacillus spp., Clostridium sporogenes, Lactobacillus spp., Lactococcus lactis, Leuconostoc mesenteroides, Listeria spp., Pediococcus cerevisiae, Staphylococcus aureus, and Streptococcus agalactiae. Furthermore, it possesses the physico-chemical properties of an ideal antimicrobial agent in terms of water solubility, thermal resistance, and stability against acid/alkali (pH 2.0 to 9.0) treatment. Edman degradation, mass spectroscopy, and nuclear magnetic resonance were used to sequence native and chemically modified paenibacillin. While details of the tentative sequence need to be elucidated in future work, the peptide was unequivocally characterized as a novel lantibiotic, with a high degree of posttranslational modifications. The coproduction of polymyxin E1 and a lantibiotic is a finding that has not been reported earlier. The new strain and associated peptide are potentially useful in food and medical applications.

Determination of Quality Characteristics of Holothuria tubulosa, (Gmelin, 1788) in Turkish Sea (Aegean Region) Depending on Sun Drying Process Step Used in Turkey

ABSTRACT There are around 500 species of sea cucumber but few (around 10-17) are valuable commercially. In Turkey, an Aegean region species, Holothuria tubulosa, is collected by divers and kept alive until processed. Generally, Chinese methods and processing techniques of sea cucumbers are applied in Turkey. Processing steps in Turkey consist of cleaning, gutting, boiling, cooling, sun drying, packaging and storage. In this study, quality characteristics of Holothuria tubulosa were determined depending on a sun drying process step used in Turkey: water activity (aw) and microbial quality of the sea cucumber were determined during sun drying period at different air conditions (temperature, wind velocity, humidity). Proximate analysis (crude protein, crude fat, moisture, carbohydrate) and chemical quality control analyses (total volatile base-nitrogen, trimetylamine-nitrogen, and thiobarbituric acid reactive substances) were also determined before and after sun drying of Holothuria tubulosa. According to the results of analysis, no quality criteria reached the maximum acceptability limit for the product.

Effectiveness of Lemon Juice in the Elimination of Salmonella Typhimurium in Stuffed Mussels

Street foods are becoming more and more prominent in countries all over the world. There are many reports of disease due to consumption of street foods contaminated by pathogens. With the modern trend toward more natural preservatives, the use of organic acids can achieve a good microbiological safety in food. In the present study, stuffed mussels were inoculated with Salmonella Typhimurium suspension to provide initial populations of approximately 6 and 3 log CFU/g. After inoculation, samples were treated with fresh lemon juice and lemon dressing for 0, 5, and 15 min, and pathogens were enumerated by using direct plating on brilliant green agar. Treatment of stuffed mussels inoculated at high inoculum level, with lemon juice and lemon dressing for different exposure times caused reduction ranging between 0.25 and 0.56 log CFU/g and 0.5 and 0.69 log CFU/g, respectively, whereas in stuffed-mussel samples inoculated at low level, lemon juice and lemon dressing caused 0.08 to 0.25 log CFU/g and 0.22 to 0.78 log CFU/g reductions, respectively. Results of the study showed that both lemon juice and lemon dressing used as flavoring and acidifying agents for stuffed mussels caused slight decrease in Salmonella Typhimurium as an immediate inhibitor, but this effect increased by time. However, treatment of stuffed mussels with the inhibitors until 15 min is not enough to prevent Salmonella Typhimurium outbreaks related to stuffed mussels.

Microbiological evaluation of stuffed mussels.

Stuffed mussel is a traditional food, sold by street vendors in coastal parts of Turkey and other Mediterranean countries. In the present study, the microbiological quality of not only the stuffing mixture, but also the outer surface of the stuffed mussels was evaluated for 1 year, and the effect of the ambient temperatures on the prevalence and the count levels of the microorganisms were evaluated. Fifty samples (750 stuffed mussels in total) were collected periodically, and microbiological analyses were performed by standard procedures for aerobic plate count, coliforms, fecal coliforms, Enterobacteriaceae, Staphylococcus aureus, Bacillus cereus, and Vibrio spp. Aerobic plate counts above 5 log CFU/g were obtained in 16 and 72% of stuffing mixture samples at high and low ambient temperatures, respectively, and average aerobic plate counts of outer surface samples at high and low ambient temperatures were 3.21 and 4.34 log CFU/ml, respectively. The prevalence and the count levels of coliforms, fecal coliforms, Enterobacteriaceae, and Vibrio spp. (except for the prevalence of Vibrio spp. in stuffing mixture samples) in the samples at high ambient temperatures were considerably higher compared with those at low ambient temperatures (P < 0.05). High frequencies of pathogens S. aureus and B. cereus were found in stuffing mixture samples at high ambient temperatures, with averages of 2.84 and 2.94 log CFU/g, respectively (P < 0.05). The result of this investigation indicates that stuffed mussels as a street food may constitute a potential health hazard, especially at high ambient temperatures, depending on contamination level and lack of sanitary practices, and therefore, handling practices should require more attention and improvement.

Antimicrobial Effect of Sour Pomegranate Sauce on Escherichia coli O157 : H7 and Staphylococcus aureus

Pomegranate sauce is one of the most popular pomegranate products produced in Turkey. This study was conducted to determine the minimum inhibitory concentrations (MICs) of both traditional and commercial sour pomegranate sauce samples on Staphylococcus aureus (ATCC 25923) and Escherichia coli O157:H7 (ATCC 43895). The initial microflora of the pomegranate sauce samples was determined by performing the enumerations of total aerobic mesophilic bacteria, yeast and mold, S. aureus, E. coli, and the determination of Salmonella spp. MIC tests were applied to the neutralized and the original (unneutralized) sour pomegranate sauce samples in order to put forth the inhibition effect depending on low pH value. It was found that inhibitory effect of the traditional and the commercial samples, except one sample, on pathogens was not only due to the acidity of the products. The results of MIC tests indicated that although both traditional and commercial samples showed a considerable inhibitory effect on test microorganisms, the traditional pomegranate sauce samples were more effective than the commercial ones.

Quality and Shelf-Life Assessment of Pasteurized Trout Soup During Refrigerated Storage

The aim of this study was to investigate the quality changes of pasteurized soup prepared from smoked trout trimmings during 8 months of refrigerated storage at 3°C. Thiobarbituric acid (TBA, mg malonaldehyde/kg), total volatile content (TVB-N, mg N/100 g), total aerobic mesophilic plate count, pH value, color measurement, and sensory evaluation were used to determine quality changes. After 8 months of storage, TBA values reached 0.83 ± 0.09 mg malonaldehyde/kg. Despite a marked increase in the TBA value at Month 8, the soup was still of acceptable quality. The TVB-N value was close to the European Commission limit on fresh fish at Month 4, and further increase was not significant (p > 0.05). Total aerobic mesophilic count reached a maximum value of 4.15 ± 0.23 log cfu/g at Month 2 with 3.20 ± 0.02 log cfu/g at Month 8. The soup had an overall acceptability score of 7.16 ± 0.68 (“like moderately” on a 1- to 9-point hedonic scale). Results suggest that smoked trout trimmings can be used to maximize the value of co-products by producing a ready-to-eat soup.

İMMÜNOTERAPİ VE PROPOLİSİN KANSER İMMÜNOTERAPİSİNDE KULLANIM POTANSİYELİ

Son yillarda kanser hastaligi oldukca yaygin olarak gorulmektedir. Halk sagligi icin buyuk tehlike olusturan kanser hastaliginin tedavi yontemleri uzerinde yenilikci arastirmalar yapilmaktadir. Immunoterapi immun yanitlari artiran veya azaltan terapotik ajanlar ile ortaya cikan hastaligin tedavisidir. Immunoterapinin kanser tedavisinde etkili oldugu bilinmektedir. Bu amac dogrultusunda kullanilabilirligi arastirilan, bir ari urunu olan propolis antitumor etkiler gostermesi ile dikkat cekmektedir. Bunun yani sira antibakteriyel, antimikrobiyal, antifungal, antiviral ve sitotoksik etkileri oldugu bilinmekte olan propolisin son yillarda immunomodulator etkileri incelenmektedir. Arastirmacilara gore propolis kanser immunoterapisinde umut vadeden bir bilesendir. Bu derlemede immunoterapi ve propolisin kanser immunoterapisinde kullanimi hakkinda bilgi verilmesi amaclanmaktadir.

Production of crispy bread snacks containing chicken meat and chicken meat powder

Chicken meat in two different forms (chicken meat and chicken meat powder) were added into white flour and whole wheat blend baguette bread formulations for protein enrichment and finally developing new and healthy snacks. The chicken meat and powder levels were 10% for white flour baguette, and 15% for whole wheat blend. The dried baguette samples were packaged under 100% N2, and physical, chemical, microbiological and sensorial properties were evaluated during 3 months of storage. Protein content of chicken meat powder added samples were found statistically higher than chicken meat added samples. Hardness of the snacks was significantly affected from type of chicken meat, such as values were higher for chicken meat added samples than chicken meat powder added samples. Lipid oxidation of the snacks was determined by TBA analysis, and TBA value for whole wheat mixture snack with 15% of chicken meat was the highest among all during storage. The highest overall acceptance score was obtained from white flour snack with 10% chicken meat. There was no coliform bacteria detected during storage and the results of yeast-mold count and aerobic plate count of snacks remained between the quantitative ranges.