Aeromonas species from Nonchlorinated distribution systems and their competitive planktonic growth in drinking water

“Aeromonas is included in the Dutch Drinking Water Decree as an indicator for elevated microbial regrowth in nonchlorinated drinking water distribution
systems (DWDS). The temporal and spatial diversity of Aeromonas species in 10 DWDS and their planktonic growth characteristics with regard to different carbon sources were investigated. Genotyping of the gyrB gene of isolates showed a nonsystematic temporal and spatial variable prevalence of seven
different Aeromonas species in these DWDS and no correlation with the level of assimilable organic carbon determined with Pseudomonas fluorescens strain P17
and Spirillum sp. strain NOX (AOC-P17/NOX concentration) and Aeromonas concentrations. Pure cultures of these seven species showed a high affinity for low
concentrations (micrograms per liter) of individual amino acids and fatty acids, compounds associated with biomass. Growth occurred at 0.5mg C/liter of an
amino acid mixture. Growth of a mixed community of Aeromonas rivuli, Aeromonas salmonicida, Aeromonas sobria, and Aeromonas veronii in drinking
water occurred in pasteurized samples; however, either no growth or decay occurred in competition with the autochthonous bacteria (nonpasteurized samples).
This community also failed to grow in nonpasteurized distribution samples from a location with a clear increase in planktonic Aeromonas concentrations
in the transported drinking water. For competitive planktonic growth of Aeromonas, an amino acid concentration of $5mg C/liter is required. AOC-P17/NOX
concentrations showed that such concentrations are not expected in Dutch drinking water. Therefore, we suspect that competitive planktonic growth is not the major cause of the observed noncompliance with the Aeromonas standard in nonchlorinated DWDS.”

(Citation: Bel, N. van, Wielen, P.W.J.J., et al. – Aeromonas species from Nonchlorinated distribution systems and their competitive planktonic growth in drinking water – Applied and Environmental Microbiology 87(2021)5, e02867-20 – DOI:10.1128/AEM.02867-20)

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