Bacterial morphological plasticity
For instance, rod shapes may allow bacteria to attach more readily in environments with shear stress (e.g., in flowing water).
Cocci may have access to small pores, creating more attachment sites per cell and hiding themselves from external shear forces.
Spiral bacteria combine some of the characteristics cocci (small footprints) and of filaments (more surface area on which shear forces can act) and the ability to form an unbroken set of cells to build biofilms.
[2] Oxidative stress, nutrient limitation, DNA damage and antibiotic exposure are examples of stressors that cause bacteria to halt septum formation and cell division.
Adopting filamentous structures, bacteria resist these phagocytic cells and their neutralizing activity (which include antimicrobial peptides, degradative enzyme and reactive oxygen species).
Furthermore, the length of the filamentous bacteria could have a stronger attachment to the epithelial cells, with an increased number of adhesins participating in the interaction, making even harder the work for (PMN).
On the other hand, other factors such as extremely tiny cells, high-speed motility, tenacious attachment to surfaces, formation of biofilms and multicellular conglomerates may also reduce predation.
[2] Bacterial responses are elicited depending on the predator and prey combinations because feeding mechanisms differ among the protists.
[12] Filamentation occurs as a direct response to these effectors that are produced by the predator and there is a size preference for grazing that varies for each species of protist.
[1] Bimodal effect is a situation that bacterial cell in an intermediate size range are consumed more rapidly than the very large or the very small.
[16] For aquatic bacteria, they can produce a wide range of extracellular polymeric substances (EPS), which comprise protein, nucleic acids, lipids, polysaccharides and other biological macromolecules.
The EPS-producing planktonic bacteria typically develop subpopulations of single cells and microcolonies that are embedded in an EPS matrix.
However, the microcolony formation can be specifically induced in the presence of predators by cell-cell communication (quorum sensing).
[17] However, there is a study showed that the probability of random contacts between predators and prey increases with bacterial swimming, and motile bacteria can be consumed at higher rates by HNFs.
For example, certain bacteria such as Chromobacterium violaceum and Pseudomonas aeruginosa can secrete toxin agents related to quorum sensing to kill their predators.
In patients treated with β-lactam antibiotics, for example, filamentous bacteria are commonly found in their clinical specimens.
[1][22] Antibiotics used to treat Burkholderia pseudomallei infection (melioidosis), for example β-lactams, fluoroquinolones and thymidine synthesis inhibitors, can induce filamentation and other physiological changes.
[22] The ability of some β-lactam antibiotics to induce bacterial filamentation is attributable to their inhibition of certain penicillin-binding proteins (PBPs).
Treatment at or below the minimal inhibitory concentration (MIC) induces bacterial filamentation and decreases killing within human macrophages.
During repair of DNA damage, the SOS response aids bacterial propagation by inhibiting cell division.
DNA damage induces the SOS response in E.coli through the DpiBA two-component signal transduction system, leading to inactivation of the ftsL gene product, penicillin binding protein 3 (PBP-3).
When overexpressed, DpiA can interrupt DNA replication and induce the SOS response resulting in inhibition of cell division.
A common shape alteration is filamentation which can be triggered by a limited availability of one or more substrates, nutrients or electron acceptors.
[2] For example, Actinomyces israelii grows as filamentous rods or branched in the absence of phosphate, cysteine, or glutathione.
