Characterization of lactobacillus delbrueckii subspecies bulgaricus and streptococcus thermophilus as lactic cultures isolated from traditional Turkish yogurts and subtyping of streptococcus thermophilus using crispr analysis and mlst

Download

index.pdf

Date

2010

Author

Altay Dede, Neslihan

Metadata

Show full item record

Item Usage Stats

361
views

138
downloads

Yogurt is a characteristic fermented dairy product of Turkey and Bulgaria and its popularity has been increasing all over the world. Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (Lactobacillus bulgaricus) are used together as starter culture in production of yogurt. The objective of this study was to isolate and characterize yogurt cultures from traditionally produced yogurts (i.e. produced without using commercial starter cultures) and to search the genotypic diversity within traditional S. thermophilus isolates. Yogurt cultures were isolated from traditionally produced yogurts collected from different regions of Turkey and identified biochemically. Acidification ability of the isolates was examined and the cultures giving best acidifying rates were further subjected to a selection in terms of their acetaldehyde production ability. Then, phage resistance and proteolytic activity of chosen isolates were tested. Finally, twenty-five L. bulgaricus and twenty-two S. thermophilus isolates were selected as cultures having best technological properties. Furthermore, subtyping studies were carried out to indicate strain diversity among isolates. S. thermophilus was selected as target organism for subtyping in this study. Clustered regularly interspaced short palindromic repeats (CRISPR) loci are highly polymorphic genetic regions, which are composed of partially palindromic direct repeats interspaced by sequences called spacers. In order to characterize S. thermophilus isolates genotypically, CRISPR1 locus of the isolates were analyzed. Additionally, nineteen isolates selected after CRISPR1 analysis were characterized using multilocus sequence typing (MLST). This provided to compare CRISPR1 analysis with MLST as a typing method. According to CRISPR1 analysis S. thermophilus isolates were grouped into 6 main clusters with a total of 15 sub-clusters. MLST results demonstrated an evolutionary relationship among these strains compatible with that derived from the CRISPR1 analysis.

Subject Keywords

Food engineering.

URI

http://etd.lib.metu.edu.tr/upload/3/12612009/index.pdf
https://hdl.handle.net/11511/19770

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

A review on grain and nut deterioration and design of the dryers for safe storage with special reference to Turkish hazelnuts Ozilgen, M; Ozdemir, M (Informa UK Limited, 2001-01-01) Turkey produces about 80% of the total hazelnut crop of the world. About 75% of the production are exported. In Turkey hazelnuts are traditionally sun dried, and may be subject to mold growth and subsequent mycotoxin formation due to prolonged drying time under humid and rainy weather conditions. Drying hazelnuts in a reasonable time after harvest is necessary for mycotoxin-free, high-quality products. In general, nuts and cereals contaminated by the toxins pose a potential hazard not only to the people of ...
Identification and killer activity of a yeast contaminating starter cultures of Saccharomyces cerevisiae strains used in the Turkish baking industry Izgu, F; Altinbay, D; Yucelis, A (Elsevier BV, 1997-04-01) The yeast contaminating the starter cultures of Saccharomyces cerevisiae fermentation strains BSP 1-4, used in the Turkish baking industry, was identified as Candida tropicalis with a killer phenotype. The activity of the killer toxin against the industrial strains was optimum at pH 3.9 and 4.1 at 22-25 degrees C. The activities of some killer toxin-producing yeasts of known phenotypes against C. tropicalis were determined. Among the yeasts tested S. cerevisiae K3 and Hansenula anamola K8 were inhibitory to...
Using multi-slice-multi-echo images with NMR relaxometry to assess water and fat distribution in coated chicken nuggets Öztop, Halil Mecit; TAKHAR, Pawan; MCCARTHY, Kathryn L.; MCCARTHY, Michael J. (Elsevier BV, 2014-03-01) Characterizing water and fat distributions in fried foods is of major importance in terms of taste and nutrition. The objective of this study was to introduce a new technique to quantify water and fat distributions of chicken nuggets coated with methylcellulose (MC) through the use of magnetic resonance imaging (MRI) and NMR relaxometry. Multi-slice-multi-echo (MSME-Spin Echo based) images were performed on a 1.03 T spectrometer for the whole chicken nuggets to obtain relaxation time distribution of differe...
Estimating factors for the demand of organic milk in Turkey Gülseven, Osman (Emerald, 2018-01-01) Purpose The purpose of this paper is to identify the sociodemographic factors that affect Turkish consumers' decision to purchase organic milk. It is also of interest to derive the demand curve for organic milk based on the consumers' stated preferences.
Encapsulation of pea protein in an alginate matrix by cold set gelation method and use of the capsules in fruit juices Narin, Ceren; Ertuğrul, Ülkü; Taş, Ozan; Şahin, Serpil; Öztop, Halil Mecit (Wiley, 2020-09-01) Plant-based proteins gained importance in recent years due to the increase in the awareness of healthy diet and in the consumption of plant-based foods. However, some features of plant-based proteins like the undesirable odor and flavor affect the sensorial properties of protein containing foods. Therefore, encapsulation of these proteins could be a good strategy to tackle with this problem. The objective of this study was to design microcapsules (beads) consisting of pea protein by using sodium alginate an...

Citation Formats

N. Altay Dede, “Characterization of lactobacillus delbrueckii subspecies bulgaricus and streptococcus thermophilus as lactic cultures isolated from traditional Turkish yogurts and subtyping of streptococcus thermophilus using crispr analysis and mlst,” Ph.D. - Doctoral Program, Middle East Technical University, 2010.