Detection and Molecular Identification of Persistent Water Vessel Colonizing Bacteria in a Table Water Factory in Nigeria

Aims: To establish organisms persistent in a table water production facility and to determine the points they entered in order to eliminate any risk of having pathogens in a water production system.

Study Design: Analytic observational studies

Place and Duration of Study: Bottling facility in Nigeria and University of Nottingham, United Kingdom. Study was between August 2011 and Sept 2013.

Methodology: Sample control points were subjected to counts of bacteria, yeasts, and mold using membrane filtration to trace the source of increased bacteria counts in a table water production factory. Organisms were identified by 16S rRNA sequencing and biofilm formation was assessed with micro titer dish biofilm formation analysis.

Results: Total bacteria and Pseudomonas Spp. count were highest in the carbon filter and 5% (v/v) chlorine used for disinfection was found to be effective against planktonic cells of 18 hour cultures of Pseudomonas Spp. isolated from the carbon filter tank. No yeasts and mold were detected and after a sand blasting exercise to clean affected tanks, total bacteria counts on tryptone glucose extract medium decreased to less than factory allowable limits of 25 cfu per 100 ml of water with no further growth of Pseudomonas Spp. on centrimide medium. Other bacteria that emerged after the sand blasting exercise were regarded as persistent but had less biofilm forming ability (p=.02) when compared with Pseudomonas aeruginosa PAO1. The persistent bacteria identified after sequencing were Aeromonas hydrophila and Serratia proteamaculans.

Conclusion: Apart from Pseudomonas Spp., other bacteria can persist in the water tanks of a water bottling facility and routine checks may fail to detect an underlying problem until it becomes obvious. Prompt corrective action ensures that public safety is not compromised. This was the first time Aeromonas hydrophila and Serratia proteamaculans were identified from the water tanks in the bottling facility.