The Biology of the Escherichia coli Extracellular Matrix

Abstract

Chapter Summary Escherichia coli (E. coli) is one of the world’s best-characterized organisms, as it has been extensively studied for over a century. However, most of this work has focused on E. coli grown under laboratory conditions that do not faithfully simulate its natural environments. Therefore, the historical perspectives on E. coli physiology and life cycle are somewhat skewed toward experimental systems that feature E. coli growing logarithmically in a test tube. Typically a commensal bacterium, E. coli resides in the lower intestines of a slew of animals. Outside of the lower intestine, E. coli can adapt and survive in a very different set of environmental conditions. Biofilm formation allows E. coli to survive, and even thrive, in environments that do not support the growth of planktonic populations. E. coli can form biofilms virtually everywhere; in the bladder during a urinary tract infection, on in-dwelling medical devices, and outside of the host on plants and in the soil. The E. coli extracellular matrix, primarily composed of the protein polymer named curli and the polysaccharide cellulose, promotes adherence to organic and inorganic surfaces, and resistance to desiccation, the host immune system and other antimicrobials. The pathways that govern E. coli biofilm formation, cellulose production, and curli biogenesis will be discussed in this book chapter, which concludes with insights into the future of E. coli biofilm research and potential therapies.

Turn Up the Heat—Food and Clinical Escherichia coli Isolates Feature Two Transferrable Loci of Heat Resistance

“…A combination of biofilm formation with heat resistance would increase a strain's persistence even further (Bojer et al, 2011). As described above, pFAM21805 contains the mrk gene cluster encoding type 3 fimbriae, which are strongly associated with bacterial biofilm formation (Burmølle et al, 2008; Hufnagel et al, 2015). Moreover, orfE of LHR2 FAM21805 encodes a putative di-guanyl cyclase, and c-di-GMP signaling has been shown to affect biofilm formation (Burmølle et al, 2008; Schroll et al, 2010; Hufnagel et al, 2015).…”

The Catabolite Repressor Protein-Cyclic AMP Complex Regulates csgD and Biofilm Formation in Uropathogenic Escherichia coli

“…How curli might be involved in IBC development is unknown; however, there is a modest correlation between curli production and initial titers of UPEC during UTI (10). Curli are important for many biofilm models, and cAMP-mediated curli production might potentially play a role during biofilm-like IBC formation (2). If cAMP acts to initiate IBC formation, then cAMP should also upregulate other IBC matrix components, such as the K1 capsule.…”

“…The biofilm lifestyle is characterized by adherence, slow growth, resistance to environmental insults, and production of an extracellular matrix (ECM) (2). CsgD is the major biofilm regulator of E. coli and of many other bacteria of the Enterobacteriaceae family (3)(4)(5), and it promotes the production of two E. coli surface appendages, the amyloid fiber curli and the fibrous glycan chain cellulose (2). CsgD represses the transcription of motility-associated genes, while mediating self and surface attachment (6)(7)(8).…”

“…Growth of E. coli can occur with either planktonic or biofilm lifestyles, the transition between which requires a highly organized shift in gene expression. The biofilm lifestyle is characterized by adherence, slow growth, resistance to environmental insults, and production of an extracellular matrix (ECM) (2). CsgD is the major biofilm regulator of E. coli and of many other bacteria of the Enterobacteriaceae family (3)(4)(5), and it promotes the production of two E. coli surface appendages, the amyloid fiber curli and the fibrous glycan chain cellulose (2).…”

Respiratory heterogeneity shapes biofilm formation and host colonization in uropathogenic Escherichia coli

“…The ECM plays a central role in biofilm physiology by providing physical protection against exogenous insults, serving as a structural scaffold, and helping to establish chemical gradients which lead to metabolic differentiation and subpopulation formation (2, 3, 17, 22). As such, disruptions to the matrix can have catastrophic consequences for the biofilm community.…”