Microbial adhesion
and spreading on surfaces are crucial aspects
in environmental and industrial settings being also the early stage
of complex surface-attached microbial communities known as biofilms.
In this work,Pseudomonas fluorescens-laden droplets on hydrophilic substrates (glass coupons) are allowed
to partially evaporate before running wetting measurements, to study
the effect of evaporation on their interfacial behavior during spillover
or splashing. Forced wetting is investigated by imposing controlled
centrifugal forces, using a novel rotatory device (Kerberos). At a defined evaporation time, results for the critical tangential
force required for the inception of sliding are presented. Microbe-laden
droplets exhibit different wetting/spreading properties as a function
of the imposed evaporation times. It is found that evaporation is
slowed down in bacterial droplets with respect to nutrient medium
ones. After sufficient drying times, bacteria accumulate at droplet
edges, affecting the droplet shape and thus depinning during forced
wetting tests. Droplet rear part does not pin during the rotation
test, while only the front part advances and spreads along the force
direction. Quantitative results obtained from the well-known Furmidge′s
equation reveal that force for sliding inception increases as evaporation
time increases. This study can be of support for control of biofilm
contamination and removal and possible design of antimicrobial/antibiofouling
surfaces.