On the 12th of October Mariya Tarazanova will defend her PhD thesis entitled “The role of microbe-matrix interactions in dairy starter culture functionality” at the Rijksuniversiteit Groningen (Prof. Jan Kok). The PhD project was carried out at NIZO under the co-supervision of Dr. Herwig Bachmann and it was part of the TiFN project Functional Fermentation that was led by NIZO. The work played on the interphase of biophysics and food physics, investigating how microbial cell surface properties influence fermented dairy products. Mariya showed that the binding of milk proteins specifically evolved in lactococci isolated from a dairy environment. She furthermore discovered a new type of pili on the lactococcal surface. High levels of the pili on the surface of lactococci lead to higher viscosity and gel hardness in fermented milk. It also significantly increased the retention of microbial cells in curd during cheese making. These findings not only open new possibilities on altering texture properties of fermented dairy products and improvements of the cheese making process but they will also be applicable for non-dairy fermentations. Four of her thesis chapters have so far been published in peer reviewed journals.
Links to publications from this thesis:
- Altering textural properties of fermented milk by using
surface-engineered Lactococcus lactis
- Cell surface properties of Lactococcus lactis reveal milk protein binding specifically evolved in dairy isolates
- Plasmid complement of Lactococcus lactis NCD0712 reveals a novel pilus gene cluster
- Influence of lactococcal surface properties on cell retention and distribution in cheese curd