Ismail Akyol

Fiber-degrading properties of anaerobic gut fungus, Orpinomyces sp. GMLF19, were investigated when it was grown on various carbon sources, namely carboxymethylcellulose, barley, oat, corncob and wheat straw. Fungi were developed under anaerobic conditions, and carboxymethylcellulase (CMCase), lichenase, and xylanase activities were determined by using DNS method. Meanwhile, the decreasing order of the enzyme activity of Orpinomyces sp. GMLF19 was observed to be lichenase > CMCase > xylanase. Relative activities of these enzymes in the isolate GMLF19 were found to be the highest when the culture was grown for 5 days. Cellulase gene domain was reproduced from chromosomal DNA and transferred into Escherichia coli with the aid of pCT plasmid vector and CMCase, lichenase and xylanase activities were determined using DNS method. The gene showed relatively higher CMCase activity and moderate lichenase activity while no xylanase activity was observed suggesting that the gene is bi-functional. The cell-associated activity of overexpressed Cel19 enzyme (E. coli cells containing this transferred gene were designated as C19) was relatively higher than extracellular activity. It was also recorded that this gene has 2 dockerin domains and 1 catalytic domain with the length of 1.585 bp, and it coded 50.59 kDa size of the protein which belongs to glycosyl hydrolase family 6.

Organic acid contents of acidified and fermented fish silages made from gibel carp (Caracius gibelio) and klunzinger’s ponyfish (Equulites klunzingeri) fishes, and from fish processing residues or by-products, were determined and studied. The silages were undertaken in wet and spray-dried fish-based raw-materials for 3 weeks at room temperature (ca. 25 °C). Selected lactic acid bacteria (LAB) of Enterococcus gallinarum, Lactobacillus brevis, Lactobacillus plantarum, Pediococcus acidilactici, and Streptococcus spp. were employed to produce fermented fish-based silages, while acidified silage was prepared resorting to the addition of formic acid (3%, v/v). Lactic and propionic acids were the dominant produced organic acids, while succinic acid was formed at the smallest amounts in fermented silages. In the acidified silage, lactic and formic acids were produced in amounts higher than 800 and 1000 mg _{organic acid}/100 g _sample, respectively. Among the fermented fish-based silages, LAB strains unfolded considerable ability to presumptively produce propionic acid in gibel carp silage (>2370 mg _{organic acid}/100 g _sample). Spray-dried fermented silages displayed significantly higher organic acid content than wet silages. Propionic acid accumulation was found at the highest levels in gibel carp silage fermented with L. plantarum (6335.40 mg _{propionic acid}/100 g _sample). This research effort pointed out the good capability of various selected lactic acid bacteria strains to produce significant amounts of organic acids—especially lactic, acetic, and propionic acids—during the fermentation of fish-based silages. In terms of food safety and quality, such a production of relatively high amounts of organic acids in wet and spray-dried fish-based silages clearly indicated their suitableness to be used for animal feed.

Brucella melitensis, Cronobacter sakazakii and Listeria monocytogenes are important foodborne pathogens in milk and milk products, which are responsible for a variety of diseases that pose serious hazards to public health and food safety. The objective of this study was to develop a novel multiplex RTi‐PCR for the detection of B. melitensis, C. sakazakii and L. monocytogenes and to characterise the potential risk of these pathogens in raw milk and cheese. The raw milk (n = 25) and cheese samples (n = 20) were analysed by multiplex RTi‐PCR assay and detected for quantification of the three pathogens. In this study, B. melitensis, C. sakazakii and L. monocytogenes were simultaneously identified using BMEII0466, mms operon and hly as target genes, respectively. The multiplex RTi‐PCR assay that was developed showed good sensitivity and selectivity for the pathogenic microorganisms (r² = 0.986–0.997). Multiplex RTi‐PCR results showed that most of the samples were contaminated with the pathogens screened.

Objectives: This study aims to investigate the genetic association between single nucleotide mutation in mitochondrial manganese superoxide dismutase and a Behçet’s disease (BD) population by using molecular techniques. Patients and methods: Ninety-three BD patients (45 males, 48 females; mean age 33.15±8.99 years; range 17 to 65 years) and 125 controls (58 males, 67 females; mean age 28.33±7.31 years; range 18 to 62 years) were genotyped by polymerase chain reaction-restriction fragment length polymorphism method. The genotypic distributions in BD patients and controls were consistent with the Hardy-Weinberg equilibrium. Results: Significant differences were observed between BD patients and controls in terms of genotypic distribution. Frequencies of alanine (Ala)/Ala, Ala/valine (Val), and Val/Val were 14.0% (n=13), 45.2% (n=42), and 40.9% (n=38) in BD patients and 21.6% (n=27), 53.6% (n=67), and 24.8% (n=31) in controls, respectively (p=0.033). Conclusion: The Val/Val genotype of the manganese superoxide dismutase gene is associated with the physiopathology of BD in a group of Turkish patients.

Streptococcus thermophilus is a lactic acid bacterium and used as starter culture in the dairy industry, mainly in the manufacture of yoghurt, with Lactobacillus delbrueckii subsp. bulgaricus. It produces lactic acid as a major fermentation end product and some carbonyl compounds through sugar metabolism. The level of metabolites could be improved using molecular biotechnology. The genes of als, encoding α-acetolactate synthase (Als), the pflA, encoding pyruvate-formate lyase activating enzyme (PflA), and the adhB which encodes alcohol dehydrogenase (AdhB) of S. thermophilus NCFB2393 strain were amplified by polymerase chain reaction and separately cloned into the overexpression vector pNZ276 under the control of the lacA promoter. The strains were transformed individually with the constructed plasmids. Their abilities to generate important metabolites such as pyruvate, lactate, formate, acetaldehyde, acetoin, ethanol, and 2,3-butanediol in LM17 medium were analyzed using high-performance liquid chromatography. High level of 2,3-butanediol was obtained by overexpressing the als gene. The level of formate increased slightly by overexpressing the pflA gene. The overexpression of the adhB gene, on the other hand, resulted in a significant increase in the ethanol level.

The present study was conducted to evaluate the lactic acid- and acetaldehyde-producing abilities of lactic acid bacterial species isolated from traditionally manufactured Turkish yogurts using HPLC. The lactic acid bacterial species purified from the yogurts were the 2 most widely used species in industrial yogurt production: Streptococcus thermophilus and Lactobacillus bulgaricus. These bacteria have the ability to ferment hexose sugars homofermentatively to generate lactic acid and some carbonyl compounds, such as acetaldehyde through pyruvate metabolism. The levels of the compounds produced during fermentation influence the texture and the flavor of the yogurt and are themselves influenced by the chemical composition of the milk, processing conditions, and the metabolic activity of the starter culture. In the study, morphological, biochemical, and molecular characteristics were employed to identify the bacteria obtained from homemade yogurts produced in different regions of Turkey. A collection of 91 Strep. thermophilus and 35 L. bulgaricus strains were investigated for their lactic acid- and acetaldehyde-formation capabilities in various media such as cow milk, LM17 agar, and aerobic-anaerobic SM17 agar or de Man, Rogosa, and Sharpe agar. The amounts of the metabolites generated by each strain in all conditions were quantified by HPLC. The levels were found to vary depending on the species, the strain, and the growth conditions used. Whereas lactic acid production ranged between 0 and 77.9 mg/kg for Strep. thermophilus strains, it ranged from 0 to 103.5 mg/kg for L. bulgaricus. Correspondingly, the ability to generate acetaldehyde ranged from 0 to 105.9 mg/kg in Strep. thermophilus and from 0 to 126.9 mg/kg in L. bulgaricus. Our study constitutes the first attempt to determine characteristics of the wild strains isolated from traditional Turkish yogurts, and the approach presented here, which reveals the differences in metabolite production abilities of the wild lactic acid bacteria strains, holds the potential for the selection of the most desirable strains to be used as starters in commercial yogurt manufacture in the future.