Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleAçık Erişim2023Scopus SJRQ3Isolation and characterization of yogurt starter cultures from traditional yogurts and growth kinetics of selected cultures under lab-scale fermentation
Kayacan Çakmakoğlu, Selma; Vurmaz, Melike; Bezirci, Emine; Kaya, Yasemin; Dikmen, Hilal; Göktaş, Hamza; Demirbaş, Fatmanur; Encu, Betül; Acar Soykut, Esra; Alemdar, Filiz
The development of new starter cultures is a crucial task for the food industry to meet technological requirements and traditional products are important reservoirs for new starter cultures. In this respect, this study aimed to isolate, identify, and determine the technological characteristics of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus strains originated from traditional yogurt samples. Genotypic discrimination of 200 isolates revealed the presence of distinct 19 S. thermophilus and 11 Lb. delbrueckii subsp. bulgaricus strains as potential starter cultures. Strain-specific properties determined the acidification capacity of the yogurt starter cultures and a higher acidification capacity was observed for S. thermophilus strains compared to Lb. delbrueckii subsp. bulgaricus strains. Proteolytic activity was found between 0.012–0.172 and 0.078–0.406 for S. thermophilus and Lb. delbrueckii subsp. bulgaricus strains, respectively. 4 of S. thermophilus and 3 of Lb. delbrueckii subsp. bulgaricus strains were found resistant to all tested bacteriophages. The antibiotic susceptibility tests of the isolates revealed that a very low antibiotic resistance was observed for the yogurt starter cultures. Finally, the growth kinetics of selected strains were determined and the maximum specific growth rate of selected S. thermophilus and Lb. delbrueckii subsp. bulgaricus was calculated as 0.527 h−1 and 0.589 h−1, respectively.
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İncele - MakaleYalnız künye2018Scopus SJRQ3Identification of Lactic Acid Bacteria from Spontaneous Rye Sourdough and Determination of Their Functional Characteristics
Ispirli, Hümeyra; Demirbaş, Fatmanur; Yüzer, Mustafa O.; Dertli, Enes
This study aimed to identify Lactic Acid Bacteria (LAB) present in rye and rye bran sourdoughs that were prepared spontaneously and determine their functional characteristics. Genotypic characterization of the isolates revealed the presence of 15 distinct LAB strains belonging to 6 different species; Leuconostoc citreum, Lactobacillus plantarum, Lactobacillus graminis, Lactococcus lactis subsp. cremoris, Weissella confusa, and Weissella cibaria in rye sourdoughs. PCR screening of eps genes required for exopolysaccharide (EPS) production revealed that all strains possessed at least one gene required for EPS production and all strains produced homopolymeric EPS comprised of glucose or fructose two Lactobacillus plantarum strains produced both glucan and fructan type EPS. Antifungal activity of these strains was tested against Aspergillus niger and Penicillium chrysogenum identified in this study and several patterns were observed. The phytase activity of these strains was also determined and all strains showed phytase activity with varying degrees.
AtıfScopus24WoS15OpenAlex24İncele - MakaleAçık Erişim2018Scopus SJRQ1Glucan type exopolysaccharide (EPS) shows prebiotic effect and reduces syneresis in chocolate pudding
İspirli, Hümeyra; Demirbaş, Fatmanur; Dertli, Enes
Exopolysaccharides (EPS) of lactic acid bacteria are important biopolymers that can improve the physicochemical properties of food products and act as prebiotics. In this study the physicochemical role and the prebiotic effects of a glucan type EPS with (α1-3) and (α1-6) linkages were assessed in chocolate pudding containing Lactobacillus rhamnosus GG as a probiotic strain. The functions of EPS were determined by developing three different formulations: control, probiotic (Lactobacillus GG) and symbiotic pudding (Lactobacillus GG + EPS) samples. The pH and acidity of the symbiotic pudding sample were higher than the probiotic and the control samples during the 28-day of storage period. Similarly, an important level of increment in Lactobacillus GG levels in symbiotic sample was observed compared to the probiotic sample suggesting the prebiotic role of the α-glucan. Importantly, the syneresis in symbiotic pudding sample reduced significantly compared to other pudding samples which is related with the physicochemical role of glucan type EPS. This study reveals the prebiotic and physicochemical roles of α-glucan type EPS in a chocolate pudding model.
AtıfScopus33WoS28OpenAlex35İncele - MakaleYalnız künye2017Scopus SJRQ1Antimicrobial and functional properties of lactic acid bacteria isolated from sourdoughs
Demirbaş, Fatmanur; İspirli, Hümeyra; Kurnaz, Asena Ayşe; Yilmaz, Mustafa Tahsin; Dertli, Enes
The technological and functional properties of 15 LAB species previously isolated from sourdough were determined in terms of antifungal and antibacterial activities, production of GABA as a functional component and phytase activity. All sourdough isolates were capable of producing GABA and Weissella paramesenteroides N-7 and Lactobacillus paralimentarius E-106 showed the highest and the lowest production levels as 18,43 mM and 3,39 mM, respectively determined by HPLC analysis. The antifungal activity of these strains were tested against Aspergillus niger and Penicillium chrysogenum and two strains Lactobacillus paraplantarum N-15 and L. paralimentarius E-106 showed significant inhibitory effects to these mould species. Generally, different levels of antibacterial activity of these species were observed against food-borne pathogens but only one strain showed low levels of inhibitory effect to Salmonella typhimurium but not the other strains. The PCR detection of several bacteriocin coding genes revealed that all strains were harboured at least one bacteriocin gene among the tested genes. Finally, all strains showed phytase activity but these activity was dependant on strain specific conditions. This study revealed some important techno-functional properties of sourdough LAB strains which can play crucial roles on sourdough technology.
AtıfScopus73WoS60OpenAlex68İncele - MakaleYalnız künye2017Scopus SJRQ1Characterization of functional properties of Enterococcus spp. isolated from Turkish white cheese
İspirli, Hümeyra; Demirbaş, Fatmanur; Dertli, Enes
Enterococcus species was isolated from Turkish white cheese and genotypic characterization of these isolates revealed the presence of 12 distinct strains belonging to 5 different species: Enterococcus faecium, E. faecalis, E. durans, E. gallinarum and E. italicus. All strains showed good survival ability under bile salt conditions. The antibiotic resistance of these strains was low but two strains showed high levels of resistance including resistance to vancomycin. PCR detection of virulence determinant in these isolates revealed that cheese isolate enterococci contained virulence genes common in gut and food originated enterococci and importantly two strains harboured cylB gene related to cytolysin metabolism. No complete hemolytic activity was observed for Enterococcus strains but partial hemolytic activity was observed 8 out of 12 strains. Additionally, all strains showed important levels of antimicrobial activity against food-borne pathogens and PCR screening of genes encoding enterocin A and B indicated the presence of enterocin B gene in all tested strains. The antimicrobial activities of the tested strains were lost after proteolytic enzyme treatments but no alteration was observed at different pHs and after heat treatments. In summary, this study reflected characteristics of Enterococcus strains presented in Turkish white cheese in terms of functional and safety perspectives.
AtıfScopus56WoS55OpenAlex68İncele - Proje2016Fermente ürünlerden izole edilecek laktik asit bakterilerinde homopolimerik ve heteropolimerik ekzopolisakkarit (Eps) üreten türlerin molküler metotlar ile açığa çıkarılması
Arici, Muhammet; Demirbaş, Fatmanur; Dertli, Enes; Mercan, Emin
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- MakaleAçık Erişim2015Scopus SJRQ2Characterization of functional properties of enterococcus faecium strains isolated from human gut
İspirli, Humeyra; Demirbaş, Fatmanur; Dertli, Enes
The aim of this work was to characterize the functional properties of Enterococcus faecium strains identified after isolation from human faeces. Of these isolates, strain R13 showed the best resistance to low pH, bile salts, and survival in the simulated in vitro digestion assay, and demonstrated an important level of adhesion to hexadecane as a potential probiotic candidate. Analysis of the antibiotic resistance of E. faecium strains indicated that in general these isolates were sensitive to the tested antibiotics and no strain appeared to be resistant to vancomycin. Examination of the virulence determinants for E. faecium strains demonstrated that all strains contained the virulence genes common in gut-and food-originated enterococci, and strain R13 harboured the lowest number of virulence genes. Additionally, no strain contained the genes related to cytolysin metabolism and showed hemolytic activity. The antimicrobial role of E. faecium strains was tested against several pathogens, in which different levels of inhibitory effects were observed, and strain R13 was inhibitory to all tested pathogens. PCR screening of genes encoding enterocin A and B indicated the presence of these genes in E. faecium strains. Preliminary characterization of bacteriocins revealed that their activity was lost after proteolytic enzyme treatments, but no alteration in antimicrobial activity was observed at different pHs (3.5 to 9.5) and after heat treatments. In conclusion, this study revealed the functional characteristics of E. faecium R13 as a gut isolate, and this strain could be developed as a new probiotic after further tests.
AtıfScopus41WoS37OpenAlex42İncele
