Mechanism of attachment of swarm cells of Thiothrix nivea

Abstract

Swarm cells of Thiothrix nivea were found to possess a group of fimbriae at one pole. The other pole either was bare or possessed from one to three fimbriae. By using this polarity as a marker, it was found that the initial step in attachment of swarm cells involves the fimbriated pole and that this initial step is followed by the production of holdfast material.

The Selective Value of Bacterial Shape

“…In many rod-shaped bacteria, adhesins (attachment proteins) are located specifically at the cell poles (31,41,72,127,184,195). In fact, over 90% of E. coli cells adhere to polystyrene particles by one pole, suggesting that localized domains mediate the interactions (145).…”

“…But the benefits can entail more than this. For example, members of the genera Thiothrix and Caulobacter, which have holdfasts at one end, stick to one another to form rosettes (33,184). Such an arrangement leaves one end of each cell or chain of cells exposed to the environment, free to take up nutrients or to entrap passing prokaryotes (218).…”

“…Pseudomonas aeruginosa binds to filaments of the fungus Candida albicans, with the initial contact being made by type IV pili at one pole of the bacterium (127), and the sticky holdfast molecules of prosthecate bacteria are located at the tip end of one of their appendages (61,65,253,255). Many gliding bacteria express pili at one pole (195), the fimbriated pole of Thiothrix nivea initiates attachment (184), and attachment of Mycoplasma pneumoniae to glass surfaces may be easier for an elongated cell because the negative charge repulsion is reduced by approaching tip first (72). These behaviors are consistent with an advantage for concentrating adhesin molecules at the tip ends of cellular structures (31 …”

Microbial Surface Colonization and Biofilm Development in Marine Environments

“…Some other marine bacteria may also produce a holdfast, as indicated by their ability to form rosettelike aggregates, a characteristic associated with (though not shown to date to be directly connected to) holdfast production (593)(594)(595). The expression of the holdfast seems to be inducible, by direct contact with a surface or other bacteria or by specific microbial physiological status or environmental conditions (591)(592)(593)(596)(597)(598). In Caulobacter crescentus, a sequence of specific steps is involved in surface colonization, with initial reversible adhesion mediated by pili, followed by an arrest of flagellar rotation and subsequent induction of a holdfast for irreversible adhesion (599).…”

“…Although most holdfast-producing (or rosette-forming) bacteria possess a polar monotrichous flagellum (590)(591)(592), not all of the holdfastproducing bacteria have a polar flagellum or flagella. Some bacteria use polar fimbriae for initial surface contact, followed by the use of the holdfast for subsequent irreversible attachment, which is likely induced by fimbria-surface interactions (596,597). Genes encoding the Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) homologue Tad and Flp fimbrial proteins are present in select MRC bacteria (610), likely playing a role in surface colonization (595).…”