Engineering Lactococcus lactis for the production of trehalose, a strategy to improve stress resistance

ITQB PhD Seminar

Title: Engineering Lactococcus lactis for the production of trehalose, a strategy to improve stress resistance

Speaker: Ana Lúcia Carvalho

Laboratory: Cell Physiology and NMR

Abstract

Trehalose is widespread in Nature, often synthesized in response to environmental stresses such as freezing, dehydration, cold, heat and osmotic stress. In particular we have detected high levels of trehalose in Propionibacterium freudenreichii grown under acidic stress, a result that led us to propose that the production of this disaccharide in Lactococcus lactis could improve its viability in extreme conditions namely in acidic environments. To engineer L. lactis for the production of trehalose the endogenous pgmB and yeeA, which encode β phosphoglucomutase and trehalose-6-phosphate phosphorylase, were cloned. The resulting construct was further manipulated by cloning upstream of the catabolic genes a trehalose-6-phosphate phosphatase gene from P. freudenreichii. Engineered strains were analyzed for trehalose production by NMR spectroscopy. During growth, trehalose (mM range) was detected intra and extracellularly. Engineered and control strains were grown until mid-exponential phase and their viability tested under different stress conditions. The viability of the control strain was drastically affected at pH 3, when submitted to freeze drying, and at low temperature (4ºC), conditions which were considerably better endured by the trehalose producers.

Short CV

1999-2004: Degree in Biochemistry by Faculdade de Ciências da Universidade de Lisboa.
2005: Research student in the Cell Physiology and NMR group at ITQB, under the supervision of Professor Dra Helena Santos.
2007: PhD student in the Cell Physiology and NMR and Lactic Acid Bacteria & In Vivo NMR groups, under the supervision of Professor Dra. Helena Santos and co-supervision of Dra. Ana Rute Neves. Research area: A systems biology approach towards the development of Lactic Acid Bacteria with improved resistance to acid stress.