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Identification of potentially pathogenic bacteria in
a water distribution system in Vanderbijlpark,
South Africa
Basadi Motlhabatlou1*, Peter
Stegmann2**, Michael Pillay3***
1 National Food Technology Research Centre,
Private Bag 008 Kanye, Botswana
2Department of Biotechnology, Vaal
University of Technology, Private Bag X021, Vanderbijlpark,
1911, South Africa
3 Erudite Language Editing, 4 Nevin Street,
Vanderbijlpark, 1911
*Email: basadimoth@gmail.com
**Email: peterstegmann13@gmail.com
***Email: michaelpillay1950@gmail.com
Water distribution
systems;
Biofilms;
Heterotrophic plate
count bacteria;
Pathogenicity
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Abstract
Knowledge of microorganisms in water distribution
systems is vital in determining the final quality of potable water. Water
quality appears to decline significantly in the distribution pipes, which
is primarily attributed to the existence of biofilms. Biofilms harbour many
microorganisms, including heterotrophic plate count bacteria (HPC). HPCs
are generally used to measure the microbiological quality of drinking
water. This study assessed the presence of HPC bacteria in biofilms
obtained from four water distribution sites in Vanderbijlpark,
a suburb of Gauteng Province in South Africa. Virulence characteristics,
including enzyme analysis and antibiotic resistance of the bacteria, were
determined. Biochemical and molecular techniques were used to identify the
pathogenic organisms. Water samples were also obtained from Rand Water, the
leading supplier of potable to the area, and the Vaal River, the ultimate
water source. Fifty-two HPC bacteria were isolated on R2A. Initial
screening for potential pathogenic isolates indicated that 76% of the
isolates demonstrated β-haemolysis, which is the complete breakdown of the
red blood cells on horse blood agar and an indication of pathogenicity.
None of the isolates from the final treated water at the treatment works demonstrated
β-haemolysis. The enzymes associated with the haemolytic isolates included
DNase (31%), lecithinase (17%), coagulase (17%),
hyaluronidase (14%), proteinase (14%), gelatinase (6%) and lipase (3%). The
antibiotic tests showed that the following percentage of HPC isolates were
resistant at these sites: SE1 (33%), Sharpeville (25%), SE3 (25%), CE1
(14%) and the Vaal River (23%). Sequencing of rDNA genes showed that potentially
pathogenic bacteria,
including Bacillus spp., Klebsiella spp., Pseudomonas sp.
and E. coli were present in the water distribution
system in Vanderbijlpark.
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