Identification of Aeromonas veronii genes required for colonization of the medicinal leech, Hirudo verbana
Molecular microbiology published in J Bacteriol (2007)
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.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Zusammenfassung
Signature-tagged mutagenesis screen identified 46 colonization-deficient Aeromonas veronii mutants in Hirudo verbana, including a >25,000-fold defect in the lpp Braun's lipoprotein mutant.
Warum dies für die Hirudotherapie relevant ist
This study used signature-tagged mutagenesis to screen 3,850 transposon mutants of Aeromonas veronii and identified 46 genes required for colonization of the Hirudo verbana digestive tract, including genes involved in surface modification, regulation, nutrition, and host interaction. A notable finding was that a mutant in Braun's lipoprotein (lpp) showed a >25,000-fold colonization defect and increased SDS sensitivity, suggesting additional antimicrobial properties in the leech crop. This is relevant to ASH because it illuminates the molecular mechanisms underpinning the leech–symbiont relationship, which is central to the biology of medicinal leeches. However, the study does not address hirudotherapy directly, involves no leech secretome components, and its findings are preclinical/basic science with no immediate clinical application.
Zitation
Identification of Aeromonas veronii genes required for colonization of the medicinal leech, Hirudo verbana.
Silver AC et al. · Journal of bacteriology, 2007
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