Acinetobacter: Portrait of a Genus

Attachment to and biofilm formation on abiotic surfaces by Acinetobacter baumannii: involvement of a novel chaperone-usher pili assembly system

“…This property could explain the ability of this pathogen to persist successfully in medical environments where cells could be subjected to the shearing forces of a liquid stream, such as those found with catheters and respiratory tubes, or allowed to persist on less disturbed surfaces such as those of hospital furniture and bed linen . The formation of biofilms at different temperatures and the presence of extracellular material surrounding the attached cells that is stained with calcofluor white are also in accordance with the ability of this pathogen to grow within a wide range of temperatures and produce capsule and exopolysaccharides Towner et al, 1991). It is also clear that A. baumannii 19606 attaches to and forms biofilm structures on hydrophobic (plastic) as well as hydrophilic (glass) surfaces, with much denser cell conglomerates located at the liquid-air interface.…”

“…Taken together, the data show that this is indeed a polycistronic operon that encodes functions required for pili assembly and biofilm formation. Based on the nucleotide composition, it appears that part of this gene cluster has been acquired by A. baumannii 19606 from an unrelated source by lateral gene transfer, a possibility that is in accordance with the well known natural competence and ability of members of this genus to acquire DNA easily from different sources (Towner et al, 1991).…”

“…This attachment phenotype that depends on the formation of thin filaments is very similar to what we have observed with A. baumannii 19606, which is discussed in more detail below. The amorphous material seen between cells, cell stacks and particularly covering the top cell layer formed above the broth meniscus may represent exopolysaccharides, compounds known to be produced by environmental and clinical isolates of Acinetobacter (Towner et al, 1991). Taken together, the data indicate that environmental and clinical members of the Acinetobacter genus use similar strategies to attach to solid surfaces and to initiate the formation of biofilm structures that allow them to persist and proliferate under harsh conditions.…”

“…Cell motility mediated either by appendages such as flagella and pili or the action of glycopeptidolipids is required for biofilm formation by bacteria such as P. aeruginosa (O'Toole & Kolter, 1998a), P. fluorescens (O'Toole & Kolter, 1998b) and Mycobacterium smegmatis (Recht et al, 2000), respectively. The lack of this cell behaviour was one of the criteria used by Baumann et al (1968) to name this genus Acinetobacter, although twitching and gliding motility have been observed when some isolates were tested on semi-solid media (Towner et al, 1991). All our attempts failed to detect any type of motility with the A. baumannii 19606 prototype strain, indicating that its ability to form biofilms does not depend on this cell property, at least under the experimental conditions used in this work.…”

Molecular characterization of benzyl alcohol dehydrogenase and benzaldehyde dehydrogenase II of Acinetobacter calcoaceticus

“…The two structural genes had codon-usage patterns typical for Acinetobacter structural genes (data not shown) [18] and had GjC contents of 44 % and 42 % for xylC and xylB, respectively. These values are typical for acinetobacters [19].…”