scholarly journals Symbiosis of Aeromonas veronii Biovar sobria and Hirudo medicinalis, the Medicinal Leech: a Novel Model for Digestive Tract Associations

1999 ◽  
Vol 67 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Joerg Graf
Keyword(s):  
Digestive Tract ◽  
Bacterial Species ◽  
Bacterial Flora ◽  
Variable Region ◽  
Medicinal Leech ◽  
Hirudo Medicinalis ◽  
Bacterial Growth Rate ◽  
Culturable Bacterium ◽  
Aeromonas Veronii

ABSTRACT Hirudo medicinalis, the medicinal leech, is applied postoperatively in modern medicine. Infections by Aeromonasoccur in up to 20% of patients unless a preemptive antibiotic treatment is administered. The associated infections demonstrate the need for a better understanding of the digestive tract flora ofH. medicinalis. Early studies reported the presence of a single bacterial species in the digestive tract and suggested that these bacteria were endosymbionts contributing to the digestion of blood. In this study, we cultivated bacteria from the digestive tract and characterized them biochemically. The biochemical test results identified the isolates as Aeromonas veronii biovar sobria. This species identification was supported by sequence comparison of a variable region of the genes coding for 16S rRNA. In a colonization assay, a rifampin-resistant derivative of a symbiotic isolate was fed in a blood meal to H. medicinalis. The strain colonized the digestive tract rapidly and reached a concentration similar to that of the native bacterial flora. For the first 12 h, the in vivo doubling time was 1.2 h at 23°C. After 12 h, at a density of 5 × 107 CFU/ml, the increase in viable counts ceased, suggesting a dramatic reduction in the bacterial growth rate. Two human fecal isolates, identified as Aeromonas hydrophila and A. veronii biovar sobria, were also able to colonize the digestive tract. These data demonstrate that the main culturable bacterium in the crop of H. medicinalis isA. veronii biovar sobria and that the medicinal leech can be used as a model for digestive tract association ofAeromonas species.

scholarly journals Spatial and Temporal Population Dynamics of a Naturally Occurring Two-Species Microbial Community inside the Digestive Tract of the Medicinal Leech

2007 ◽  
Vol 73 (6) ◽  
pp. 1984-1991 ◽  
Author(s):  
Yoshitomo Kikuchi ◽  
Joerg Graf
Keyword(s):  
Population Dynamics ◽  
Digestive Tract ◽  
Bacterial Species ◽  
Single Species ◽  
Medicinal Leech ◽  
Aeromonas Veronii ◽  
Lectin Staining ◽  
Naturally Occurring ◽  
Hirudo Verbana

ABSTRACT The medicinal leech, Hirudo verbana, is one of the simplest naturally occurring models for digestive-tract symbioses, where only two bacterial species, Aeromonas veronii bv. sobria (γ-Proteobacteria) and a Rikenella-like bacterium (Bacteroidetes), colonize the crop, the largest compartment of the leech digestive tract. In this study, we investigated spatial and temporal changes of the localization and microcolony structure of the native symbionts in the crop, after ingestion of a sterile blood meal, by fluorescence in situ hybridization. The population dynamics differed between the two symbiotic bacteria. A. veronii was detected mainly as individual cells inside the intraluminal fluid (ILF) during 14 days after feeding (daf) unless it was found in association with Rikenella microcolonies. The Rikenella-like bacteria were observed not only inside the ILF but also in association with the luminal surface of the crop epithelium. The sizes of Rikenella microcolonies changed dynamically through the 14-day period. From 3 daf onward, mixed microcolonies containing both species were frequently observed, with cells of both species tightly associating with each other. The sizes of the mixed microcolonies were consistently larger than the size of either single-species microcolony, suggesting a synergistic interaction of the symbionts. Lectin staining with succinylated wheat germ agglutinin revealed that the planktonic microcolonies present in the ILF were embedded in a polysaccharide matrix containing N-acetylglucosamine. The simplicity, symbiont-symbiont interaction, and mixed microcolonies of this naturally occurring, digestive-tract symbiosis lay the foundation for understanding the more complex communities residing in most animals.

scholarly journals Complement Resistance Is Essential for Colonization of the Digestive Tract of Hirudo medicinalis by Aeromonas Strains

2003 ◽  
Vol 69 (7) ◽  
pp. 4268-4271 ◽  
Author(s):  
Thomas R. Braschler ◽  
Susana Merino ◽  
Juan M. Tomás ◽  
Joerg Graf
Keyword(s):  
Digestive Tract ◽  
Complement System ◽  
Medicinal Leech ◽  
Hirudo Medicinalis ◽  
Aeromonas Veronii ◽  
Complement Resistance

ABSTRACT From the crop of the medicinal leech, Hirudo medicinalis, only Aeromonas veronii bv. sobria can be cultured consistently. Serum-sensitive A. veronii mutants were unable to colonize H. medicinalis, indicating the importance of the mammalian complement system for this unusual simplicity. Complementation of one selected mutant restored its ability to colonize. Serum-sensitive mutants are the first mutant class with a colonization defect for this symbiosis.

scholarly journals Identification of Aeromonas veronii Genes Required for Colonization of the Medicinal Leech, Hirudo verbana

2007 ◽  
Vol 189 (19) ◽  
pp. 6763-6772 ◽  
Author(s):  
Adam C. Silver ◽  
Natasha M. Rabinowitz ◽  
Stefan Küffer ◽  
Joerg Graf
Keyword(s):  
Digestive Tract ◽  
Pathogenic Bacteria ◽  
Antimicrobial Property ◽  
Sodium Dodecyl ◽  
Medicinal Leech ◽  
Wild Type ◽  
Aeromonas Veronii ◽  
Hirudo Verbana

ABSTRACT Most digestive tracts contain a complex consortium of beneficial microorganisms, making it challenging to tease apart the molecular interactions between symbiont and host. The digestive tract of Hirudo verbana, the medicinal leech, is an ideal model system because it harbors a simple microbial community in the crop, comprising the genetically amenable Aeromonas veronii and a Rikenella-like bacterium. Signature-tagged mutagenesis (STM) was used to identify genes required for digestive tract colonization. Of 3,850 transposon (Tn) mutants screened, 46 were identified as colonization mutants. Previously we determined that the complement system of the ingested blood remained active inside the crop and prevented serum-sensitive mutants from colonizing. The identification of 26 serum-sensitive mutants indicated a successful screen. The remaining 20 serum-resistant mutants are described in this study and revealed new insights into symbiont-host interactions. An in vivo competition assay compared the colonization levels of the mutants to that of a wild-type competitor. Attenuated colonization mutants were grouped into five classes: surface modification, regulatory, nutritional, host interaction, and unknown function. One STM mutant, JG736, with a Tn insertion in lpp, encoding Braun's lipoprotein, was characterized in detail. This mutant had a >25,000-fold colonization defect relative to colonization by the wild-type strain at 72 h and, in vitro, an increased sensitivity to sodium dodecyl sulfate, suggesting the presence of an additional antimicrobial property in the crop. The classes of genes identified in this study are consistent with findings from previous STM studies involving pathogenic bacteria, suggesting parallel molecular requirements for beneficial and pathogenic host colonization.

scholarly journals Bacterial flora associated with diseased freshwater ornamental fish

2017 ◽  
Vol 61 (4) ◽  
pp. 445-449 ◽  
Author(s):  
Natalia Walczak ◽  
Krzysztof Puk ◽  
Leszek Guz
Keyword(s):  
Bacterial Species ◽  
Bacterial Flora ◽  
Ornamental Fish ◽  
Citrobacter Freundii ◽  
Bacterial Diseases ◽  
Aeromonas Veronii ◽  
Causative Agents ◽  
Diseased Fish ◽  
Shewanella Baltica ◽  
Tof Ms

AbstractIntroduction:Ornamental fish can suffer from different bacterial diseases. Among them the most prevalent are infections caused byAeromonas, Shewanella, Citrobacter, Plesiomonas, Edwardsiella, andPseudomonas.But there is a broad spectrum of rarely identified bacteria which may be causative agents of diseases. The aim of the study was to determine the species of bacteria pathogenic for fish which are prevalent in aquariums.Material and Methods:Bacteria were isolated from infected ornamental fish from pet shops and private aquariums in the Lublin region in 2015 and classified to species using MALDI-TOF MS.Results:A total of 182 isolates from ornamental fish were identified. The most frequent bacteria found in diseased fish wereAeromonas veronii(30.8% of total number of strains),A. hydrophila(18.7%),Shewanella putrefaciens(7.1%),Citrobacter freundii(7.1%),Pseudomonas spp. (7.1%),Shewanella baltica(4.9%), andPlesiomonas shigelloides(3.3%).Conclusion:Isolated bacterial species are facultative pathogens for fish and humans and may be isolated from fish without apparent symptoms of the disease.

scholarly journals Culture-Independent Characterization of the Digestive-Tract Microbiota of the Medicinal Leech Reveals a Tripartite Symbiosis

2006 ◽  
Vol 72 (7) ◽  
pp. 4775-4781 ◽  
Author(s):  
Paul L. Worthen ◽  
Cindy J. Gode ◽  
Joerg Graf
Keyword(s):  
Bacterial Community ◽  
Digestive Tract ◽  
Medicinal Leech ◽  
Rrna Gene ◽  
Polymorphism Analysis ◽  
Data Set ◽  
Clone Libraries ◽  
Host Interactions ◽  
Aeromonas Veronii ◽  
Culture Independent

ABSTRACT Culture-based studies of the microbial community within the gut of the medicinal leech have typically been focused on various Aeromonas species, which were believed to be the sole symbiont of the leech digestive tract. In this study, analysis of 16S rRNA gene clone libraries confirmed the presence of Aeromonas veronii and revealed a second symbiont, clone PW3, a novel member of the Rikenellaceae, within the crop, a large compartment where ingested blood is stored prior to digestion. The diversity of the bacterial community in the leech intestinum was determined, and additional symbionts were detected, including members of the α-, γ-, and δ-Proteobacteria, Fusobacteria, Firmicutes, and Bacteroidetes. The relative abundances of the clones suggested that A. veronii and the novel clone, PW3, also dominate the intestinum community, while other clones, representing transient organisms, were typically present in low numbers. The identities of these transients varied greatly between individual leeches. Neither time after feeding nor feeding on defibrinated blood caused a change in identity of the dominant members of the microbial communities. Terminal restriction fragment length polymorphism analysis was used to verify that the results from the clone libraries were representative of a larger data set. The presence of a two-member bacterial community in the crop provides a unique opportunity to investigate both symbiont-symbiont and symbiont-host interactions in a natural model of digestive-tract associations.

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