Engineering Adhesion of the Probiotic Strain Escherichia coli Nissle to the Fungal Pathogen Candida albicans

Engineering live biotherapeutic products against fungal
pathogens
such as Candida albicans has been suggested
as a means to tackle the increasing threat of fungal infections and
the development of resistance to classical antifungal treatments.
One important challenge in the design of live therapeutics is to control
their localization inside the human body. The specific binding capability
to target organisms or tissues would greatly increase their effectiveness
by increasing the local concentration of effector molecules at the
site of infection. In this study, we utilized surface display of carbohydrate
binding domains to enable the probiotic E. coli Nissle 1917 to adhere specifically to the pathogenic yeast Candida albicans. Binding was quantified using a
newly developed method based on the automated analysis of microscopic
images. In addition to a rationally selected chitin binding domain,
a synthetic peptide of identical length but distinct sequence also
conferred binding. Efficient binding was specific to fungal hyphae,
the invasive form of C. albicans, while
the yeast form, as well as abiotic cellulose and PET particles, was
only weakly recognized.