Starvation survival of the fish pathogen Aeromonas salmonicida in seawater

Husevåg, B

doi:10.1016/0168-6496(94)00066-6

Cited by 11 publications

(6 citation statements)

References 9 publications

(12 reference statements)

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“…,1993Austin 1991, 1994), from which it may be able to recover (Allen-Austin et ul. 1984; Husevig 1995). Such evidence is consistent with a waterborne mechanism for survival and dissemination.…”

Section: Discussionsupporting

confidence: 65%

Survival of cells and DNA of Aeromonas salmonicida released into aquatic microcosms

Deere

Porter

Pickup

et al. 1996

Journal of Applied Bacteriology

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The survival of the bacterial fish pathogen Aeromonas salmonicida, and persistence of its DNA, were monitored in aquatic microcosms using selective culture and most probable number PCR. Bacterial cells and naked DNA were released into natural non-sterile microcosms consisting of lake sediment overlayered with lake water. Two different types of surface sediment were used. One was sandy in character, taken from the shoreline whilst the other was a littoral loamy surface mud. Inoculated cells and naked DNA became undetectable from water overlayers within 4 weeks of release. Colony counts of Aer. salmonicida declined below detectable limits after 4 weeks in loamy sediment or 7 weeks in sandy sediment; however, naked DNA and DNA from released cells remained detectable for more than 13 weeks.

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Section: Discussionsupporting

confidence: 65%

Survival of cells and DNA of Aeromonas salmonicida released into aquatic microcosms

Deere

Porter

Pickup

et al. 1996

Journal of Applied Bacteriology

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“…As a recent report (22) has described the ability of a 28-kDa protein of A. salmonicida OM to form nonselective channels in planar bilayers, similar in size to those of OmpF and OmpC, and we can now say conclusively that this 28-kDa protein is in fact one of the A. salmonicida OmpA homologs (the reported sequence of the 19 N-terminal aa of this protein was identical to that of the N terminus of OmpAI), comparative analysis of the pore-forming activities of OmpAI and OmpAII is one potential function which will be analyzed in detail. A range of selective and nonselective porin activities may be important to A. salmonicida, which is found primarily in association with fish but may also survive for some time in water (18). Such studies may be facilitated by the demonstration that both OmpAI and OmpAII apparently assemble correctly into the E. coli outer membrane (Fig.…”

Section: Discussionmentioning

confidence: 99%

Aeromonas salmonicida possesses two genes encoding homologs of the major outer membrane protein, OmpA

1996

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Two homologs of the outer membrane protein OmpA were identified in Aeromonas salmonicida by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblotting, and amino-terminal sequence analyses. An A. salmonicida genomic DNA library was constructed by using GEM-11 and recombinant phage carrying both genes (ompAI and ompAII) selected by immunoscreening. A 5.0-kb BamHI fragment containing the two genes in tandem was subcloned in pBluescript and used for further subcloning and sequencing of the genes. The encoded proteins (M r ‫؍‬ 33,564 and 32,536 for mature OmpAI and OmpAII, respectively) had only 64% identity with each other and otherwise had the highest level of homology to OmpA proteins from the members of the family Enterobacteriaceae. Based on the Escherichia coli OmpA model, an eight-stranded amphipathic ␤-barrel model for the membrane assembly of the N-terminal half of OmpAI and OmpAII was predicted. Most variation between the two proteins was localized to the predicted surface loops and periplasmic turns, while the transmembrane strands and C-terminal domains were highly conserved. Expression of ompAI and ompAII separately in E. coli indicated that both genes could be independently transcribed from their own promoters and that both gene products were assembled into the E. coli outer membrane. A survey of different Aeromonas spp. by PCR revealed that possession of two tandem ompA genes was widespread among this genus. This is the first report of any bacterial species possessing two genes for homologs of this major outer membrane protein.The OmpA protein was initially identified as one of the major proteins of the outer membrane of Escherichia coli. Either a closely related homolog of this protein or a more distantly related relative has now been identified as a major protein of the outer membrane of a wide range of gramnegative bacteria (5,12,15,16,27). Major physiological functions attributed to the OmpA family include maintenance of the structural integrity and morphology of the cell (33) and porin activity (35), as well as a role in conjugation and bacteriophage binding (26). A role in bacterial virulence has been implicated for some of these proteins (9,30,37). The importance of the OmpA family of proteins has been further strengthened by the recent observation that amino acid (aa) sequence homology extends to certain proteins from grampositive bacteria as well as lipoproteins from gram-negative bacteria, all with the common property of interacting with peptidoglycan (10).In all cases thus far examined, cloning of the ompA (or ompA-like) gene has identified a single gene which appears to be constitutively expressed. The structure and assembly of the E. coli protein have been studied in detail. Current models (31,36) propose that E. coli OmpA is assembled into the outer membrane with a bidomain structure: an N-terminal membrane domain (residues 1 to 170), comprising an eight-transmembrane-stranded amphipathic ␤-barrel, and a C-terminal periplasmic domain (residues 171 to 325). The relative res...

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“…There are reports demonstrating the in vitro resuscitation of A. salmonicida from the VBNC state (Allen- Austin etal. 1984;Husevag 1995), whilst other workers have failed to reproduce similar results (Morgan etal. 1992;Ferguson, Glover, McGillivray & Prosser 1995).…”

Section: Discussionmentioning

confidence: 80%

“…There are a number of reports suggesting that A. salmonicida can maintain a VBNC state for prolonged periods in fresh water (Allen- Austin, Austin & Colwell 1984;Morgan, Cranwell & Pickup 1991;Morgan, Clarke, Rhodes & Pickup 1992;Moi^an, Rhodes & Pickup 1993) and sea water (Effendi & Austin 1991, 1995. These studies provide evidence that nonculturable cells are morphologically intact, containing protein, lipids, RNA, and plasmid and chromosomal DNA as well as maintaining cellular functions, such as membrane potential.…”

Section: Introductionmentioning

confidence: 88%

Direct analysis of starved Aeromonas salmonicida

Deere

Porter

Pickup³

et al. 1996

Journal of Fish Diseases

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Survival of Aeromonas salmonicida was monitored during prolonged incubation in either distilled water or lake w^ater. Culturability was determined from colony forming units enumerated on tryptone soy agar, whilst flow cytometry was used for direct analysis of viable cells after staining with fluorescent dyes which differentially stained bacteria in relation to defined cellular properties. Over time, populations of culturable cells steadily declined and were not detected after 10 days incubation in distilled water or 33 days in lake water. Flow cytometric analysis revealed that cellular properties related to viability were lost shortly after culturable cells became undetectable in distilled water. In contrast, those incubated in lake water showed little change in these properties over a 57-day experimental period. The implications of these differences are discussed, and it is concluded that A. salmonicida is capable of remaining intact and active upon prolonged incubation in lake water, although this does not conclusively prove viability.

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Starvation survival of the fish pathogen Aeromonas salmonicida in seawater

Cited by 11 publications

References 9 publications

Survival of cells and DNA of Aeromonas salmonicida released into aquatic microcosms

Survival of cells and DNA of Aeromonas salmonicida released into aquatic microcosms

Aeromonas salmonicida possesses two genes encoding homologs of the major outer membrane protein, OmpA

Direct analysis of starved Aeromonas salmonicida

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