Pellicle formation by Escherichia coli K-12: Role of adhesins and motility

Initial work to generate physically robust biofilms for biocatalytic applications revealed that Escherichia coli K-12 can form a floating biofilm at the air-liquid interface, commonly referred as pellicle. Unlike other species where pellicle formation is well-characterised, such Bacillus subtilis, there are few reports of E. pellicles in literature. In order study formation, growth model was developed and monitored over time. Mechanical forces, both motility shaking, were shown have effects on development. The role regulation curli, an amyloid protein adhesin critical studied by using promoter-green fluorescent reporters; flow cytometry confocal laser scanning microscopy used monitor curli expression time different locations. Curli found be not only crucial but also heterogeneously expressed within components extracellular polymeric substances (EPS) analysed lectins, revealing distinct morphology air-facing medium-facing sides, spatially- temporally-regulated generation EPS poly-N-acetyl glucosamine colanic acid. We discuss difference between formed K-12, pathogenic strains species, relationship solid surface-attached biofilms.