Assessment of expression of Leloir pathway genes in wild-type galactose-fermenting Streptococcus thermophilus by real-time PCR

In this study, four galactose-positive (Gal⁺) Streptococcus thermophilus strains viz. AJM, JM1, KM3 and AUKD8 and one galactose-negative (Gal⁻) S. thermophilus NCDC 218 were used to characterize the organization of Leloir pathway genes using long-range PCR, and expression of these genes were studied...

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Bibliographic Details
Published in:European food research & technology 2014-11, Vol.239 (5), p.895-903
Main Authors: Anbukkarasi, Kaliyaperumal, Nanda, Dhiraj Kumar, UmaMaheswari, Thiyagamoorthy, Hemalatha, Thiagarajan, Singh, Prashant, Singh, Rameshwar
Format: Article
Language:English
Subjects:
Agriculture
Analytical Chemistry
Annealing
Biotechnology
Chemistry
Chemistry and Materials Science
Dairy products
Enzymes
Fermentation
Food
Food Science
Forestry
galactose
Gene expression
Glucose
Glycerol
Knowledge management
Lactose
Metabolism
operon
Original Paper
Polymerase chain reaction
quantitative polymerase chain reaction
Research centers
Streptococcus thermophilus
Studies
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Summary:In this study, four galactose-positive (Gal⁺) Streptococcus thermophilus strains viz. AJM, JM1, KM3 and AUKD8 and one galactose-negative (Gal⁻) S. thermophilus NCDC 218 were used to characterize the organization of Leloir pathway genes using long-range PCR, and expression of these genes were studied using real-time PCR, in presence of different sugars. Long-range PCR results showed that both Gal⁺ and Gal⁻ isolates, the gal–lac gene order (galRKTEM–lacSZ), are conserved including the size of individual genes. The promoter sequence of the three Gal⁺ isolates (AJM, JM1 and KM3) possessed single base pair deletion at −28 region of galR and C to T substitution at −9 box galK region. In contrast, Gal⁺ AUKD8 had A to T substitution at preceding −25 region of galR. The expression of galK and galM grown in the presence of galactose was significantly higher in case of AJM (30- and 7.6-fold, respectively), followed by KM3 and JM1. In addition, galR, galT and galE showed higher expression in galactose, than in lactose and glucose medium. This study gives a preliminary idea on Leloir pathway gene expression in wild Gal⁺ S. thermophilus, and further studies may throw more light on the role of gal–lac operon in galactose metabolism.
ISSN:1438-2377
1438-2385
DOI:10.1007/s00217-014-2286-9