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Metabolic Regulation in Response to Growth Environment
Published in Kazuyuki Shimizu, Metabolic Regulation and Metabolic Engineering for Biofuel and Biochemical Production, 2017
Biofilm formation is one of the important microbial survival strategies, where biofilm development involves attachment of bacteria to surfaces and cell-cell adhesion to form microcolonies. This is useful for the cell to protect against predetors and antibiotics (Wang et al. 2005). The attachment of bacteria to abiotic and biotic surfaces is made by motility, proteinaceous adhesion, and a cell-bound polysaccharide such as PGA (poly-^-1,6-N- acetyl-D-glucosamine), where PGA is a cell-bound exopolysaccharide adhesion (Wang et al. 2005). As mentioned before, Csr plays important roles for biofilm formation, where pga operon involved in PGA formation and excretion is negatively regulated by CsrA. CsrA also negatively regulates c-di-GMP, a second messenger involved in biofilm formation and motility (Hengge 2009). Curli are extracellular proteinaceous structures extending from the cell surface for attachment during biofilm development (Barnhart and Chapman 2006). Curli filaments are activated by CsgD, where it is inversely correlated with flagella synthesis. The master regulator of flagella synthesis is FlhD2C2, which activates the genes involved in motility and chemotaxis (Thomason et al. 2012). McaS (multi-cellular adhesion sRNA) represses CsgD expression, while activates FlhD and PgaA (Thomason et al. 2012), and thus regulates the synthesis of curli flagella and polysaccharide. Moreover, biofilm formation is under catabolite repression by cAMP and Crp (Jackson et al. 2002).
Potentialities of Medicinal Plant Extracts Against Biofilm-Forming Bacteria
Published in Bakrudeen Ali Ahmed Abdul, Microbial Biofilms, 2020
Muhammad Bilal, Hira Munir, Hafiz M. N. Iqbal
This plant extract has been shown to drastically inhibit the formation of biofilm by E. coli on the surfaces of polystyrene, nylon membranes, and glass, with a quantity of 100 μg/mL, without disturbing the growth of bacteria. Ginkgolic acid present in G. biloba suppresses prophage and curli genes present in E. coli, and this compound causes these inhibitory effects. Curli and prophage genes are responsible for the production of biofilm (He et al., 2013; Lee et al., 2014a). In another research, cinnamaldehyde was reported as it affects the formation and structure of biofilm. It also inhibits the swimming motility of E. coli (Niu and Gilbert, 2004).
Engineering Living Materials: Designing Biological Cells as Nanomaterials Factories
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
Peter Q. Nguyen, Pichet Praveschotinunt, Avinash Manjula-Basavanna, Ilia Gelfat, Neel S. Joshi
Functional amyloids, especially bacteria associated curli nanofibers, are bacterial extracellular matrix proteins that have been an intense focus for development of engineered living material due to its modularity, robustness, and self-assembly properties. Curli fibers, found in most Enterobacteriaceae, consist of monomeric, β-sheet-rich CsgA protein monomers that can self-polymerize extracellularly and remain associated with the bacterial cells (Blanco et al. 2012). Each CsgA monomer can be genetically mutated or fused with heterologous domains to create fully assembled, engineered curli fibers with desired properties (Figure 8.1g). The Lu Group has explored the possibility of producing hybrid curli fibers in situ using two groups of Escherichia coli harboring different engineered CsgA plasmids with separate inducible systems. There were able to create hybrid fibers with tunable, co-block polymer-like features (Chen et al. 2014). The group also recently explored the use of engineered curli fibers for gold nanoparticle templating to create electrically conductive fibers (Seker et al. 2017). Concurrently, the Joshi group has developed the biofilm-integrated nanofiber display (BIND) platform which initially surveyed the possibility of displaying various functional domains at different lengths and structures to test the limit of the system and demonstrate the functional properties of displayed domains on the engineered fibers, such as affinity binding and specific nanoparticle templating (Nguyen et al. 2014). The Joshi group has expanded upon multiple possibilities of this platform as living materials. For example, curli fibers as catalytic surfaces were made by displaying SpyTag peptides on CsgA monomers, which in the presence of its cognate protein partner, SpyCatcher, is able to form specific biorthogonal covalent linkages. The SpyCatcher proteins heterologously fused with various enzymes of interest were used to create monolithic living catalytic surfaces (Botyanszki et al. 2015; Nussbaumer et al. 2017). The group has also engineered curli fibers to bind contaminated mercury in seawater for bioremediation applications with the use of synthetic biology to control expression of curli based on the presence of mercury (Tay, Nguyen, and Joshi 2017). In addition, the group has explored the use of BIND platform to interact with biological systems by displaying therapeutic factors on curli fibers, which implies the development of a living therapeutic platform inside the gut (Duraj-Thatte et al. 2018). Engineering of extracellular matrix proteins such as curli fibers is a significant step toward building truly advanced ELMs as the strategy involves secreting engineerable, self-assembling proteins which remain associated with live cells that continuously produce more of the materials. With the tweaking of components in the curli biogenesis pathway, and further development of the system, researchers may be able to create more complex, hierarchical living materials in the future.
Structural variations on Salmonella biofilm by exposition to river water
Published in International Journal of Environmental Health Research, 2021
Contreras-Soto Mb, Medrano-Félix Ja, Sañudo-Barajas Ja, Vélez-de la Rocha R, Ibarra-Rodríguez Jr, Martínez-Urtaza J, Chaidez C, Castro-del Campo N
Curli are extracellular protein fibers of the amyloid type being very stable and resistant to detergents, pH and Protease K, therefore formic acid (FA) or hexafluoro-2-propanol (HFIP) is needed to dissociate curli fimbriae (Steenackers et al. 2012; Reichhardt et al. 2015). CsgA is the resistant part and the major structural subunit of curli, which can be mobilized in a SDS-PAGE gel with an expected fraction close to 17.5 Kda and can be detected by Dot blot or Western blot using anti-CsgA antibodies (Zhou et al. 2012; Bordeau and Felden 2014; Evans and Chapman 2014; Nicastro et al. 2019). Figure 3 shows the CsgA fraction in SDS-PAGE (B), Western blot (C) and Dot-blot (D). All strains evaluated produce curli fimbriae as part of the biofilm matrix. The content of CsgA being greater in RDAR morphotype of Salmonella Saintpaul and Typhimurium. This component is present in the new SPAM morphotype (Figure 3B, C and D, lanes 3 and 6).