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81975

CHARACTERIZATION OF Streptococcus thermophilus ASSOCIATED WITH EGYPTIAN DAIRY PRODUCTS

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Last updated: 04 Jan 2025

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Abstract

Streptococcus thermophilus is an important industrial species that is extensively used in the preparation of fermented dairy products. The present study was designed to characterize S. thermophilus strains isolated from traditional Egyptian dairy products. Ninety-five samples of Kariesh cheese, Zabady, Laban Rayeb and Ras cheese were randomly collected, and examined for the presence of S. thermophilus. A total of 255 of lactic acid bacteria cultures could be isolated from these products and subjected to morphological and physiological examinations. Out of these isolates, 20 cultures isolated from Kariesh cheese and Laban Rayeb could be identified as S. thermophilus using a PCR analysis targeting the serB gene. These isolates were characterized on the basis of biochemical traits related to their potential use in dairy industries. This involved examining their ability to develop acidity, utilize galactose, produce exopolysaccharides and express the urease enzyme. S. thermophilus isolates were diverse in their ability to acidify milk, with the most of isolates developing moderate levels of acidity of 0.4% - < 0.6% after 6 h of incubation at 37°C.Isolates showed diversity in utilizing galactose and urease activity, yet the majority of them was unable to ferment galactose, or expressed urease. Only 1 isolate could produce exopolysaccharides. These results show that Kariesh cheese and Laban Rayeb could serve as a local source of S. thermophilus isolates of diverse technological traits that could be exploited in dairy processing.  

DOI

10.21608/jfds.2011.81975

Keywords

Streptococcus thermophilus, kariesh cheese, Laban Rayeb, PCR

Authors

First Name

Rana

Last Name

El-Tokhy

MiddleName

T.

Affiliation

Food Safety and Microbial Physiology Laboratory, Dairy Dept., Fac. Agric., Mans. Univ.

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First Name

M.

Last Name

Zin El-Din

MiddleName

M.

Affiliation

Faculty of Tourism and Hotels, Mansoura University

Email

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City

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Orcid

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First Name

W.

Last Name

El-Sharoud

MiddleName

M.

Affiliation

Food Safety and Microbial Physiology Laboratory, Dairy Dept., Fac. Agric., Mans. Univ.

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Volume

2

Article Issue

8

Related Issue

12347

Issue Date

2011-08-01

Receive Date

2020-04-12

Publish Date

2011-08-01

Page Start

493

Page End

504

Print ISSN

2090-3650

Online ISSN

2090-3731

Link

https://jfds.journals.ekb.eg/article_81975.html

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https://jfds.journals.ekb.eg/service?article_code=81975

Order

9

Type

Original Article

Type Code

886

Publication Type

Journal

Publication Title

Journal of Food and Dairy Sciences

Publication Link

https://jfds.journals.ekb.eg/

MainTitle

CHARACTERIZATION OF Streptococcus thermophilus ASSOCIATED WITH EGYPTIAN DAIRY PRODUCTS

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Article

Created At

22 Jan 2023