Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleYalnız künye2017Scopus SJRQ2Highly Enantioselective Production of Chiral Secondary Alcohols Using Lactobacillus paracasei BD101 as a New Whole Cell Biocatalyst and Evaluation of Their Antimicrobial Effects
Yılmaz, Durmuşhan; Şahin, Engin; Dertli, Enes
Chiral secondary alcohols are valuable intermediates for many important enantiopure pharmaceuticals and biologically active molecules. In this work, we studied asymmetric reduction of aromatic ketones to produce the corresponding chiral secondary alcohols using lactic acid bacteria (LAB) as new biocatalysts. Seven LAB strains were screened for their ability to reduce acetophenones to their corresponding alcohols. Among these strains, Lactobacillus paracasei BD101 was found to be the most successful at reducing the ketones to the corresponding alcohols. The reaction conditions were further systematically optimized for this strain and high enantioselectivity (99%) and very good yields were obtained. These secondary alcohols were further tested for their antimicrobial activities against important pathogens and significant levels of antimicrobial activities were observed although these activities were altered depending on the secondary alcohols as well as their enantiomeric properties. The current methodology demonstrates a promising and alternative green approach for the synthesis of chiral secondary alcohols of biological importance in a cheap, mild, and environmentally useful process.
AtıfScopus41WoS35OpenAlex38
İncele - MakaleYalnız künye2017Scopus SJRQ1Characterization of lactic acid bacteria from yogurt-like product fermented with pine cone and determination of their role on physicochemical, textural and microbiological properties of product
Sert, Durmuş; Mercan, Emin; Dertli, Enes
The aim of this study was to understand how pine cone (PC) addition could acidify the milk and result in the production of yogurt. For this purpose, yogurts were produced with three different pine cones which were classified according to collection period; PC-1 (October), PC-2 (November) and PC-3 (December). Physicochemical, textural and microbiological properties were determined as quality criteria on the yogurt samples. Importantly, Lactic Acid Bacteria (LAB) were isolated and identified from yogurt samples. 26 of 80 yogurt isolates were identified. The incubation time of yogurts until the pH reached 4.6–4.7 was ∼3.5–4 h at 45 °C. Textural properties of yogurt PC-3 increased as compared to PC-1 and PC-2 which was found to be related with high LAB numbers in PC-3. Similarly, the highest dry matter, water holding capacity, acidity values were determined in the yogurt PC-3 whereas PC-1 had the lowest values. The lowest pH value was found in yogurt PC-3 related to LAB counts. Lactobacillus spp. and Streptococcus spp. counts of yogurts ranged between 5.95-6.82 and 6.32–6.99 log cfu/g, respectively. Also, LAB species were identified as Streptococcus thermophilus and Lactobacillus plantarum in all yogurt samples showing that pine cones somehow harbour the yogurt starters.
AtıfScopus60WoS58OpenAlex59İncele - 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 - MakaleAçık Erişim2017Scopus SJRQ2Highly Enantioselective Production of Chiral Secondary Alcohols with Candida zeylanoides as a New Whole Cell Biocatalyst
Şahin, Engin; Dertli, Enes
The increasing demand for biocatalysts in synthesizing enantiomerically pure chiral alcohols results from the outstanding characteristics of biocatalysts in reaction, economic, and ecological issues. Herein, fifteen yeast strains belonging to three food originated yeast species Candida zeylanoides, Pichia fermentans, and Saccharomyces uvarum were tested for their capability for asymmetric reduction of acetophenone to 1-phenylethanol as biocatalysts. Of these strains, C. zeylanoides P1 showed an effective asymmetric reduction ability. Under optimized conditions, substituted acetophenones were converted to corresponding optically active secondary alcohols in up to 99% enantiomeric excess and at high yields. The preparative scale asymmetric bioreduction of 4-nitroacetophenone (1m) by C. zeylanoides P1 gave (S)-1-(4-nitrophenyl)ethanol (2m) with 89% yield and > 99% enantiomeric excess. Compound 2m has been obtained in an enantiomerically pure and inexpensive form. Additionally, these results indicate that C. zeylanoides P1 is a promising biocatalyst for the synthesis of chiral alcohols in industry.
AtıfScopus32WoS30İncele - 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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- BildiriYalnız künye2016Scopus SJRQ1Functional properties of lactic acid bacteria (LAB) playing crucial roles on sourdough biotechnology
Dertli, Enes; Yilmaz, Mustafa Tahsin
AtıfWoS1OpenAlex2İncele - BildiriAçık Erişim2016Scopus SJRQ1Determination of functional characteristics, presence of virulence factors and antibiotic resistance of enterococci isolated from Turkish White-Cheese
Akin, Nihat; Dertli, Enes; Ispirli, Humeyra; Yuvasen, Ayse; Akaya, Zuhal
- MakaleYalnız künye2016Rheological and Molecular Characterization of Modified Pectin from Sugar Beet Meal
Yilmaz, Mustafa Tahsin; Muslu, Asli; Dertli, Enes; Toker, Omer Said
The pectin was produced from sugar beet pulp, one of the significant waste of sugar industry, at optimum conditions (pH, time and temperature). Then, the modification was carried out using pectinase. FT-IR (Fourier transform infrared spectroscopy) and HPLC (high performance liquid chromatography) analysis were performed to characterize the differences between modified and unmodified pectin. FT -IR analysis revealed the specific regions of pectin and 1600-1800 cm-1 bands. Galacturonic acid content was analyzed by HPLC. The obtained results revealed that the modified pectin had higher galacturonic acid content. In addition, flow properties of the modified pectin was also determined. The flow characteristics of modified pectin was observed to change.
AtıfWoS1İncele - MakaleYalnız künye2016EFFECT OF IN SITU EXOPOLYSACCHARIDE PRODUCTION ON SENSORY PROPERTIES OF TURKISH-TYPE FERMENTED SAUSAGE
Yilmaz, Mustafa Tahsin; Toker, Omer Said; Tatlisu, Nevruz Berna; Arici, Muhammet; Dertli, Enes
In this study, effect of in situ exopolysaccharide (EPS) production on sensory properties of Turkish-type fermented sausage (sucuk) was determined. Sausage mixes were prepared as four groups: (a) Control group, control sausage samples produced without LAB addition, with natural flora, (b) Strain 1 group, sausage samples produced by using Strain 1 (EPS+ Lactobacillus plantarum 162 R strain), (c) Strain 2 group: sausage samples produced by using Strain 2 (EPS+ Leuconostoc mesenteroides N6) and (d) Mixture group, sausage samples produced by using mixture of Strain 1 and Strain 2. These mixes were fermented at 14, 16 and 18 degrees C for 8, 12 and 16 days. Fermentation conditions remarkably affected the sensory properties of the sausage using different EPS producing EPS. These results of this study demonstrated the importance of in situ EPS production on final sensory properties of sausage.
AtıfWoS1İncele - MakaleAçık Erişim2016Scopus SJRQ1EpsA is an essential gene in exopolysaccharide production in Lactobacillus johnsonii FI9785
Dertli, Enes; Mayer, Melinda J.; Colquhoun, Ian J.; Narbad, Arjan
Lactobacillus johnsonii FI9785 has an eps gene cluster which is required for the biosynthesis of homopolymeric exopolysaccharides (EPS)-1 and heteropolymeric EPS-2 as a capsular layer. The first gene of the cluster, epsA, is the putative transcriptional regulator. In this study we showed the crucial role of epsA in EPS biosynthesis by demonstrating that deletion of epsA resulted in complete loss of both EPS-1 and EPS-2 on the cell surface. Plasmid complementation of the epsA gene fully restored EPS production, as confirmed by transmission electron microscopy and nuclear magnetic resonance (NMR) analysis. Furthermore, this complementation resulted in a twofold increase in the expression levels of this gene, which almost doubled amounts of EPS production in comparison with the wild-type strain. Analysis of EPS by NMR showed an increased ratio of the heteropolysaccharide to homopolysaccharide in the complemented strain and allowed identification of the acetylated residue in EPS-2 as the (1,4)-linked βGlcp unit, with the acetyl group located at O-6. These findings indicate that epsA is a positive regulator of EPS production and that EPS production can be manipulated by altering its expression.
AtıfScopus43WoS38OpenAlex39İncele - MakaleYalnız künye2016Scopus SJRQ1Characterisation of lactic acid bacteria from Turkish sourdough and determination of their exopolysaccharide (EPS) production characteristics
Dertli, Enes; Mercan, Emin; Arici, Muhammet; Yilmaz, Mustafa Tahsin; Sağdiç, Osman
A total of 249 Lactic Acid Bacteria (LAB) isolates were found in traditional Turkish wheat sourdoughs from Eastern Black Sea region of Turkey. Genotypic characterization of these isolates revealed the presence of 47 distinct LAB strains belonging to 11 different species: Lactobacillus plantarum, Lactobacillus paraplantarum, Lactobacillus curvatus, Lactobacillus rossiae, Lactobacillus sanfranciscensis, Lactobacillus brevis, Lactobacillus paralimentarius, Weissella paramesenteroides, Leuconostoc mesenteroides, Leuconostoc pseudomesenteroides and Weissella cibaria. The sourdough LAB microbiota differed depending on the sample origin and the collection period and heterofermentative LAB were dominant. The number of different species within a sourdough varied from 3 to 6 with the association of different hetero- and homofermentative LAB species. Exopolysaccharide (EPS) production characteristics of the isolates were determined and strain specific properties appeared to be important for the final EPS yields. Genes required for homopolysaccharide (gtf and lev) and heteropolysaccharide (epsA, epsB, p-gtf) production were PCR detected and several distribution patterns were observed. Results of this study confirmed the biodiversity of LAB species in traditional Turkish sourdough and highlighted the importance of EPS production in sourdough LAB strains.
AtıfScopus174WoS157OpenAlex168İncele - MakaleAçık Erişim2016Scopus SJRQ1Development of a fermented ice-cream as influenced by in situ exopolysaccharide production: Rheological, molecular, microstructural and sensory characterization
Dertli, Enes; Toker, Omer S.; Durak, M. Zeki; Yilmaz, Mustafa T.; Tatlisu, Nevruz Berna; Sagdic, Osman; Cankurt, Hasan
This study aimed to investigate the role of in situ exopolysaccharide (EPS) production by EPS+ Streptococcus thermophilus strains on physicochemical, rheological, molecular, microstructural and sensory properties of ice cream in order to develop a fermented and consequently functional ice-cream in which no stabilizers would be required in ice-cream production. For this purpose, the effect of EPS producing strains (control, strain 1, strain 2 and mixture) and fermentation conditions (fermentation temperature; 32, 37 and 42°C and time; 2, 3 and 4 h) on pH, S. thermophilus count, EPS amount, consistency coefficient (K), and apparent viscosity (η50) were investigated and optimized using single and multiple response optimization tools of response surface methodology. Optimization analyses indicated that functional ice-cream should be fermented with strain 1 or strain mixture at 40-42°C for 4 h in order to produce the most viscous ice-cream with maximum EPS content. Optimization analysis results also revealed that strain specific conditions appeared to be more effective factor on in situ EPS production amount, K and η50 parameters than did fermentation temperature and time. The rheological analysis of the ice-cream produced by EPS+ strains revealed its high viscous and pseudoplastic non-Newtonian fluid behavior, which demonstrates potential of S. thermophilus EPS as thickening and gelling agent in dairy industry. FTIR analysis proved that the EPS in ice-cream corresponded to a typical EPS, as revealed by the presence of carboxyl, hydroxyl and amide groups with additional α-glycosidic linkages. SEM studies demonstrated that it had a web-like compact microstructure with pores in ice-cream, revealing its application possibility in dairy products to improve their rheological properties.
AtıfScopus86WoS74OpenAlex98İncele - MakaleYalnız künye2016Scopus SJRQ1A novel antifungal surface-coating application to limit postharvest decay on coated apples: Molecular, thermal and morphological properties of electrospun zein–nanofiber mats loaded with curcumin
Yilmaz, Azime; Bozkurt, Fatih; Cicek, Perihan Kubra; Dertli, Enes; Durak, Muhammed Zeki; Yilmaz, Mustafa Tahsin
Coating surfaces of fruit with electrospun zein mats with functionalized antimicrobial properties can be a novel strategy to prevent fungal colonization on fruit surfaces. In this study, we tested curcumin-loaded electrospun zein nanofibers (CLZN) in terms of limitation of postharvest decay on CLZN–coated apples infected with Botrytis cinerea and Penicillium expansum. Mixtures of zein and curcumin (the curcumin amounts of 2.5 and 5 wt% based on the weight of zein powder) were electrospun to yield cylindrical and ultrafine (< 350 nm in diameter) polymeric nanofibers. In addition, molecular, thermal, zeta potential and morphological properties of the CLZN as well as their encapsulation efficiency and releasing kinetics were determined, revealing that the developed zein-based scaffolds showed high encapsulation efficiency, molecular interactions with curcumin within nanofibers, alterations in physical states of these components, smooth beadless structure and good thermal (an endothermic peak at 152 °C) and dispersion stability (− 24 mV of ζ potential) properties. In vitro antifungal activity tests conducted at 27 °C for six days showed that CLZN were effective against growth of the tested fungal pathogens, exhibiting almost 40–50% inhibition of mycelial growth of the fungal pathogens; but the antifungal effect against P. expansum was but two-fold higher than that against B. cinerea. In vivo tests conducted at 23 °C with 75% humidity for six days confirmed in vitro test results in terms of both visual inspections on uncoated and coated apples, revealing almost 50% reduction in lesion diameter measured on coated apples infected with Penicillium expansum. Our results suggest that CLZN mats open up new opportunities for a novel application of edible and biodegradable antifungal coating material with the ability to hinder fungal proliferation on coated apples during storage period. Industrial relevance We coated the surfaces of fruits with electrospun mats with functionalized antimicrobial properties to prevent fungal colonization on fruit surface. The coating of apples with curcumin-loaded zein nanoparticles (CLZNs) limited the postharvest decay caused by the fungal pathogens, Penicillium expansum and Botrytis cinerea. This study showed that by encapsulation of curcumin into zein-based nanofibers considerably increased the antifungal effectiveness of curcumin. Our results highlighted the potential use of the CLZN as an effective fungicidal coating material against P. expansum and B. cinerea and suggested that CLZNs can be promising tools to compete with synthetic fungicide counterparts of curcumin. The results of this study should be of great importance to industrial applications in terms of development of natural, but effective preservatives as alternative to synthetic ones.
AtıfScopus111WoS85OpenAlex110İncele - MakaleAçık Erişim2016Scopus SJRQ1Effects of in situ exopolysaccharide production and fermentation conditions on physicochemical, microbiological, textural and microstructural properties of Turkish-type fermented sausage (sucuk)
Dertli, Enes; Yilmaz, Mustafa Tahsin; Tatlisu, Nevruz Berna; Toker, Omer Said; Cankurt, Hasan; Sagdic, Osman
In this work, the role of in situ exopolysaccharide (EPS) production under different fermentation conditions on physicochemical, microbiological, textural and microstructural properties of sucuk was determined. For this purpose, the effect of EPS producing strains (control, strain 1, strain 2 and mixture) and fermentation conditions (fermentation temperature; 14, 16 and 18 °C and time; 8, 12 and 16 days) on physicochemical, microbiological, textural and microstructural properties were investigated using response surface methodology. In situ EPS production was observed to remarkably affect these properties while fermentation conditions were also seen to dominantly influence the physicochemical properties of sucuk, revealing that the ripening temperature appeared to be more determinant factor. EPS producing cultures enhanced the textural properties of sucuk which became harder, less adhesive and tougher. The microstructural analysis revealed the formation of web-like structure by in situ EPS production in sucuk mix during fermentation process. This study revealed the importance of in situ EPS production on final technological properties of sucuk.
AtıfScopus48WoS43OpenAlex54İncele - MakaleYalnız künye2015Scopus SJRQ2Yoğurttan ekzopolisakkarit üreten streptococcus thermophilus suşunun izolasyonu ve tanımlanması
Dertli, Enes
Production of exopolysaccharides (EPS) by starter Lactic acid bacteria (LAB) gained special interest due to technological role of thesenatural polymers. Yogurt samples were collected from diferent households in Turkey and bacterial strains were isolated and evaluatedfor EPS production. Strains potentially producing EPS were then identified to species level with 16S rRNA sequencing. An EPS producerStreptecoccus thermophilus strain was identified from yogurt samples. EPS was extracted from culture supernatants of S. thermophilus andpartially purified and structural analysis of the crude EPS by FTIR spectroscopy revealed the presence of typical functional groups relatedto exopolysaccharides. This study explains the identification of a potential starter culture for yogurt production with EPS production.
AtıfTR Dizin4
İncele - MakaleAçık Erişim2015Scopus SJRQ2Isolation and identification of an exopolysaccharide producer Streptococcus thermophilus strain from Turkish yogurt; [Yoğurttan ekzopolisakkarit üreten Streptococcus thermophilus suşunun izolasyonu ve tanımlanması]
Dertli, Enes
Production of exopolysaccharides (EPS) by starter Lactic acid bacteria (LAB) gained special interest due to technological role of these natural polymers. Yogurt samples were collected from different households in Turkey and bacterial strains were isolated and evaluated for EPS production. Strains potentially producing EPS were then identified to species level with 16S rRNA sequencing. An EPS producer Streptecoccus thermophilus strain was identified from yogurt samples. EPS was extracted from culture supernatants of S. thermophilus and partially purified and structural analysis of the crude EPS by FTIR spectroscopy revealed the presence of typical functional groups related to exopolysaccharides. This study explains the identification of a potential starter culture for yogurt production with EPS production.
AtıfScopus7WoS7OpenAlex1İncele - MakaleAçık Erişim2015Scopus SJRQ2Impact of exopolysaccharide production on functional properties of some Lactobacillus salivarius strains
Mercan, Emin; İspirli, Hümeyra; Sert, Durmuş; Yılmaz, Mustafa Tahsin; Dertli, Enes
The aim of this work was to characterize functional properties of Lactobacillus salivarius strains isolated from chicken feces. Detection of genes responsible for exopolysaccharide (EPS) production revealed that all strains harbored a dextransucrase gene, but p-gtf gene was only detected in strain E4. Analysis of EPS production levels showed significant alterations among strains tested. Biofilm formation was found to be medium composition dependant, and there was a negative correlation with biofilm formation and EPS production. Autoaggregation properties and coaggregation of L. salivarius strains with chicken pathogens were appeared to be specific at strain level. An increment in bacterial adhesion to chicken gut explants was observed in L. salivarius strains with the reduction in EPS production levels. This study showed that strain-specific properties can determine the functional properties of L. salivarius strains, and the interference of these properties might be crucial for final selection of these strains for technological purposes.
AtıfScopus19WoS16OpenAlex21İncele - 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 - MakaleYalnız künye2015Scopus SJRQ1Thermal loop test to determine structural changes and thermal stability of creamed honey: Rheological characterization
Karasu, Salih; Toker, Omer Said; Yilmaz, Mustafa Tahsin; Karaman, Safa; Dertli, Enes
This study was the first attempt to understand if thermal stability of any food product during storage could be determined. In this respect, a novel method, namely, the thermal loop test was used to determine structural changes and thermal stability of creamed honey in this study. The novelty of this method was that thermal stability of a product is tested within a number of thermal cycles over a determined range of temperature. Creamed honey was characterized in terms of physicochemical, thermomechanical and rheological properties. It showed non-Newtonian thixotropic behavior at all temperature levels (10, 25 and 40 °C). Time-dependent flow behavior was successfully defined by Weltman and second order structural models. Hysteresis loop area depended on temperature and decreased with increase in temperature. Creamed honey had liquid-like structure, showing that it had more pronounced viscous nature than elastic nature (G″ > G′). Temperature sweep tests were conducted to determine temperature dependency of η50, G′ and G″ values using Arrhenius equation. These test results confirmed the thermal stability test results, revealing that thermal loop test can be an accurate method to determine thermal stability of similar food products, as a new information. Relative structural index value (Δ) increased with number of thermal loop, suggesting that creamed honey had low thermal stability and showed a great structural change by the thermal stress applied between 5 °C and 50 °C. These results suggest that crystallized honey be abstained from large temperature fluctuations to avoid from irreversible changes in rheological characters; thus, to maintain spreadability.
AtıfScopus45WoS43OpenAlex47İncele - MakaleAçık Erişim2015Scopus SJRQ2Decontamination of Escherichia coliO157: H7 and Staphylococcus aureus from Fresh-Cut Parsley with Natural Plant Hydrosols
Törnük, Fatih; Dertli, Enes
The inhibitory effects of sage, rosemary, oregano and thyme hydrosols were evaluated against Escherichia coliO157:H7 and Staphylococcus aureus inoculated on parsley at high and low concentrations. Following the pathogen inoculations, parsley samples were washed with the hydrosols and sterile tap water as a control for 0, 20, 40 and 60min, and reductions on pathogen counts were determined. Sterile tap water was ineffective on all conditions tested. After 20min of application, oregano and thyme hydrosols were able to significantly (P<0.05) reduce E.coliO157:H7 counts on low inoculum level, while all hydrosols showed significant reductions (P<0.05) on high inoculum levels at this period. Additional reductions on E.coliO157:H7 counts were observed with the increasing time. S.aureus was more sensitive to hydrosol treatments, and oregano hydrosol was able to completely eliminate S.aureus after 40min. In conclusion, decontamination of foodborne pathogens from fresh-cut vegetables can be achieved by hydrosol treatments.
AtıfScopus14WoS11OpenAlex16İncele