assessment and biofilm formation of bacterial communities associated with
drinking water distribution system
Ishaq and B. Ali*
Microbiology and Molecular Genetics, University of the Punjab, Quaid-i-Azam
Campus, Lahore-54590, Pakistan
Author E-mail: firstname.lastname@example.org
Drinking water biofilms
Escherichia coli O157
Paper received :
Revised received :
Re-revised received :
Accepted : 29.03.2018
Aim: Potable water can
be contaminated with variety of bacterial pathogens during the distribution
process. The aim of this study was to analyze the bacterial risks associated
with drinking water supply system of the city Kasur, Pakistan.
Methodology: Water analysis
was accomplished by following the most probable number (MPN) method.
Bacterial diversity was determined by 16S rRNA gene sequencing. Screening for
O157 antigen was conducted for all the identified strains of Escherichia
coli. Strains were also screened for antibiotic susceptibility and biofilm
Results: Analysis showed
≥ 2400 MPN index for few water samples. 16S rRNA sequencing confirmed
the presence of bacterial strains belonging to the genera of Escherichia,
Pseudomonas, Bacillus, Exiguobacterium, Klebsiella, Acinetobacter, Aeromonas,
Enterobacter, Citrobacter and Shigella. Serological analysis also
detected the presence of pathogenic strains of E. coli O157. Antibiotic
sensitivity pattern showed the resistance of strains against nitrofurantoin,
cephalexin, nalidixic acid and ampicillin. For biofilm formation, Ex.
artemiae DG1 and An. haemolyticus J4 were the most active biofilm
producer in single cultures.
Interpretation: Majority of the
water samples were contaminated in terms of coliforms. Biofilm formation by
bacterial strains indicated that water distribution network might be
colonized by potential human pathogens.
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