Developing mucus-biomimetic models to study mucus-bacteria interactions

Mucus layers are in close contact with the underlying tissues as well as the
bacterial species colonised within the vicinity of the human gut. Mucus-bacteria
interactions could affect human health in various ways. Different types of in vitro
models have been developed to study these interactions. However, models which
can simulate the environment of the living mucosa are still pending to be
established for further work. In this project, mucus biomimetic models were
developed and applied in both surface (2-dimentional) level (coated on surface
of glass coverslips) and 3-dimentional (3-D) level (part of a 3-D hydrogel matrix)
for investigation of mucus-bacteria interactions.

Commercially available porcine gastric mucins were purified and crosslinked with
natural crosslinking agent genipin to develop the mucus biomimetic gel. By spin
coating on a glass coverslip surface, functionality of this mucus biomimetic gel
material was confirmed by increasing the biofilm biomass (~3-fold increase) of
mucin-degrading bacteria in a static condition. On the other hand, this mucus
biomimetic material was blended with agarose to serve as a co-gel matrix to
immobilise bacterial cells at low cell density in a commercial prototype microfluidic
platform for single-cell phenotype profiling called CellCity®. By mixing with
agarose, the physical properties of the mucus biomimetic gel (e.g. gel strength)
was improved. Bacteria in this mucus simulated environment showed an earlier
quorum sensing (QS) response compared to in the normal agarose gel matrix.
Results of this thesis have contributed to gain insights into mucus-bacteria
interactions by creating two types of mucus-like in vitro system which resemble
aspects of the natural mucus environment.