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UID:1113@biotech.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20230626T020000
DTEND;TZID=Asia/Jerusalem:20230626T030000
DTSTAMP:20230611T115734Z
URL:https://biotech.technion.ac.il/events/horizontal-plasmid-transfer-driv
 es-antibiotic-resistance-in-intensive-aquaculture-farms/
SUMMARY:Horizontal Plasmid Transfer Drives Antibiotic Resistance in Intensi
 ve Aquaculture Farms
DESCRIPTION:Genetic transfer\, including horizontal plasmid transfer (HPT)\
 , drives bacterial evolution by mediating the sharing of adaptive traits s
 uch as antibiotic resistance (AR). However\, HPT mechanisms of diverse pla
 smids in natural environments in complex bacterial populations remain unex
 plored. Here we assessed the role of HPT in the emergence and spread of an
 tibiotic-resistant genes (ARGs) in intensive frog farms. Metagenomic analy
 ses of frog farm sediments\, combined with high throughput antibiotic susc
 eptibility examination of bacterial isolates\, revealed Escherichia coli a
 nd Edwardsiella tarda as the core antibiotic resistant bacteria (ARB). Upo
 n sequencing of the genomes of 95 multidrug-resistant bacteria (mainly E. 
 coli\, E. tarda\, Citrobacter\, and Klebsiella)\, we identified 250 plasmi
 ds (average size ≥110 kb) that harbored various ARGs flanked by mobile g
 enetic elements (MGEs). AR against commonly used antibiotics strongly corr
 elated with plasmid borne ARGs. Many plasmids (57%) were conjugative\, wit
 h 20% being multi-replicons. Sixty-two percent of these plasmids belonged 
 to 32 distinct groups that tracked ARG dissemination via inter- and intra-
 species HPT. Multiple plasmids in various combinations (2-3 per host)\, we
 re shown to preferentially co-habit to achieve the desirable AR phenotype 
 for adaptation. Same mobile ARGs (flanked by MGEs) were found in different
  locations on similar or different plasmids from the same or different bac
 terial hosts. Blasting public datasets also identified plasmids from other
  environmental niches globally\, that were highly identical to those from 
 the frog farms. Our data provide a real time record of the spread of ARGs 
 in intensive animal farms and the mechanisms involved in resistome develop
 ment.\nSince the majority of isolated plasmids were conjugative\, we then 
 investigated interactions between two high-efficient conjugative plasmids 
 from E. coli (pET82-3 and pET979-1) that had different type IV secretion s
 ystem machineries. We address two questions in these studies: (1) How does
  one conjugative plasmid affect the transferability of another conjugative
  plasmid in the same host? (2) How does the presence of a conjugative plas
 mid in one bacterial host affect the conjugation of an incoming plasmid? T
 he two plasmids were labelled with either gfp or mScarlet genes to track c
 onjugation using florescence microscopy. Mutations in the ATPase genes (vi
 rB4 /virD4 in pET82-3 or traC /traD in pET979-1) completely blocked the tr
 ansfer of the respective plasmid. Remarkably\, the mutated plasmid could b
 e transferred in the presence of a different native plasmid\, although at 
 relatively low conjugation frequency. Additionally\, the bacterial host wi
 th the presence of a plasmid prevented accepting the same plasmid but not 
 a different plasmid. This indicates that an exclusion system is present on
  each unique conjugative plasmid. Understanding conjugation at the molecul
 ar level can help us develop strategies to combat the spread of ARGs and p
 revent the emergence of superbugs. Our pioneering work will also shed ligh
 t on the mechanisms involved in resistome development in natural communiti
 es.
CATEGORIES:סמינרים
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