characterization of lytic phages specific to antibiotic resistant isolates of
Pseudomonas fluorescens infecting Labeo rohita and Clarias
batrachus of Sub Himalayan region
Dinkar1, A. K. Sharma1, A. S. Ninawe2 and Y.
Animal Science, M.J.P. Rohilkhand University, Bareilly - 243006, India
Biotechnology, CGO Complex, Lodhi Road, New Delhi-110 003, India
Author E-mail: email@example.com
received : 30.05.2016
received : 29.09.2016
received : 10.10.2016
Accepted : 16.12.2016
Aim: This investigation
was aimed to develop antibacterial strategy to circumvent the problem of
antibiotic resistant P. fluorescens infecting L. rohita and
Indian walking catfish, C. batrachus in Himalayan and Sub Himalayan
lytic phages (PFPD, PFPK, PFPN and PFPC) were isolated against ten isolates
of pathogenic P. fluorescens following overlay method using water and
bottom sediments of Himalayan and Sub Himalayan regions. One step growth
experiment was carried out to know the eclipse, latent periods and burst size
of phages. Phage genomic DNA was extracted following chloroform: phenol:
isoamyl method and digested using restriction enzymes (EcoRI and Hind III)
(Bangalore genei, Bangalore) and isolation of phage protein was made as per
Laemmli (1970) with slight modification.
were identified as a member of family Siphoviridae (isometric head of
236.42nm and non-contractile long tail of 521.22 nm) with having ds DNA of
20-21 kbp and structural viral proteins of 22 - 102 kDa. Phages exhibited minimum
eclipse period (10 - 15 min), latent period (20 min) and highest burst size
of 130. These phages conferred clear lytic plaques in the lawn of 8 of 10
(80%) host bacterium at 0.01 MOI, tolerated wide range of temperature (25 to
350C), pH (6.5 to 8.0), yielded highest titer (108 pfu)
at 30 ±5 0C and exhibited highest (99%) in vitro lytic
activities. The host bacterium did not develop resistance to all the phages
studied during the entire period of the study.
profound in vitro lytic attributes of PFPD and PFPK phages and their
tolerance to temperature and pH at par with aquaculture activities reveals
that they may be a suitable option to alleviate transmission of even
systematic P. fluorescens infection in hatchery and culture system.
This information will provide more insight into the potential use of phage to
mitigate incidences of Bacterial Haemorrhagic Septicaemia in aquaculture.
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