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OJVRTM
Online Journal of Veterinary Research©
Volume 19(10):
653-662, 2015.
Effect of colicins on diarrheic Escherichia
coli
Zahra Shirazi1 Yahya Tahamtan2*
1Microbiology
Department, Jahrom Branch, Islamic
Azad University, Jahrom,2Bacteriology Department, Razi Vaccine and Serum Research Institute.
Shirazi Z. Tahamtan Y., Effect of colicins on diarrheic Escherichia coli, Onl
J Vet Res., 19 (10): 653-662, 2015.
Colicinogenic E. coli (CEC)
strains were tested on verotoxin serotypes O157:H7
(clone 1), five Non-O157:H7 (clone 2) and eight K99 (clone 3) strains. DEC and
test strains were inoculated onto Luria bertani (LB) broth (O/N). O/N culture of CEC strains
was spotted onto LA and LA supplemented mitomycin C
(LAM) dry plates previously lawn with DEC.
Plates were incubated O/N at 37°C and inhibitory activity
against DEC strains was defined as a clear zone around colicin-producing
strains. PCR was used to isolate positive and negative virulence factors among
DEC strains and colicin gene in CEC strains.
Inhibition of DEC
strains occurred for 33.3 to 94.4% of clones with most and least inhibition
related to Col IaIb, E-mix and Col M respectively.
The presence of mitomycin C in the LAM medium
increased inhibition of colicins and those not
inhibited on LA. Sensitivity of DEC
strains to colicins was DEC clone 1 >2 >3 on LA
and DEC clone 2 >1 >3 on LAM.
Inhibition on LAM medium may have been induced by injury to DEC strains
by mitomycin C sensitivity. Insensitivities to colicins on LA and LAM could be due to wild-type DEC
strains, immunity genes, loss of genes coding for outer membrane protein receptors,
inherent genetic differences in genes regulating production of colicins, host cell SOS system or unknown mechanisms.
Keywords: Colicin, Diarrhia, Escherichia
coli ,
inhibition.
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