عنوان

Metabolic Network-Based Analysis of Cheese Starter Cultures as a Microbial Community

Number

TLpq2469221059

.Language of Text, Soundtrack etc

انگلیسی

Title Proper

Metabolic Network-Based Analysis of Cheese Starter Cultures as a Microbial Community

General Material Designation

[Thesis]

First Statement of Responsibility

Özcan, Emrah

Subsequent Statement of Responsibility

Öner, Ebru Toksoy

Name of Publisher, Distributor, etc.

Marmara Universitesi (Turkey)

Date of Publication, Distribution, etc.

2019

Specific Material Designation and Extent of Item

151

Dissertation or thesis details and type of degree

Ph.D.

Body granting the degree

Marmara Universitesi (Turkey)

Text preceding or following the note

2019

Text of Note

There is almost no pure culture in nature, but rather microorganisms are open to interact with other organisms, and different species share the same habitat. Therefore, microbial community studies enable nature to be understood better. Cheese starter cultures as a microbial community have been studied in this thesis. For this purpose, dairy-origin lactic acid bacteria (LAB), Lactococcus lactis subsp. cremoris, Lactococcus lactis subsp. lactis, Streptococcus thermophilus and Leuconostoc mesenteroides, which are commonly used LAB species in cheese starter cultures, were grown in pure and co-cultures. The co-cultures composed of L. lactis and Leu. mesenteroides species and the co-cultures composed L. lactis and S. thermophilus species were assumed to represent mesophilic and thermophilic starter cultures, respectively. The metabolic capacities of the pure and co-cultures were then comprehensively investigated by the dynamic metabolic network modelling approaches in a quantitative manner. Substrate uptake kinetics in the dynamic models were defined as a function of pH and lactic acid. The kinetic parameters were estimated using the pure culture experiments, and they were used both in the pure and co-culture models. The mesophilic co-culture models showed that pH was the major fermentation parameter that effects the co-culture biomass composition, and the models explained the mechanisms behind the suppression of the growth of Leu. mesenteroides by L. lactis strains in mesophilic starter cultures. Unlike the mesophilic co-cultures, temperature was the major fermentation parameter in thermophilic co-cultures. Since the fermentation temperature of the L. lactis and S. thermophilus pure cultures were different, the thermophilic co-cultures were grown at an average fermentation temperature. The thermophilic co-culture models could simulate the fermentations only after the individual substrate uptake rates, which are the model constraints, were multiplied by a strain-specific correction coefficient reflecting the temperature difference. Furthermore, the co-culture models estimated the individual production/consumption profiles of the various extracellular metabolites, as well as the potential metabolic interactions between the LAB in the co-cultures, which could not be obtained experimentally.

Bioengineering

Food science

Microbiology

Öner, Ebru Toksoy

Özcan, Emrah

Electronic name

p

[Thesis]

276903

a

Y