Poikilothermic Animals as a Previously Unrecognized Source of Fecal Indicator Bacteria in a Backwater Ecosystem of a Large River

Christina Frick, Julia Vierheilig, Rita Linke, Domenico Savio, Horst Zornig, Roswitha Antensteiner, Christian Baumgartner, Christian Bucher, Alfred P Blaschke, Julia Derx, Alexander K T Kirschner, Gabriela Ryzinska-Paier, René Mayer, Dagmar Seidl, Theodossia Nadiotis-Tsaka, Regina Sommer, Andreas H Farnleitner

Research output: Journal article (peer-reviewed)Journal article

14 Citations (Scopus)

Abstract

Quantitative information regarding the presence of Escherichia coli, intestinal enterococci, and Clostridium perfringens in poikilotherms is notably scarce. Therefore, this study was designed to allow a systematic comparison of the occurrence of these standard fecal indicator bacteria (SFIB) in the excreta of wild homeothermic (ruminants, boars, carnivores, and birds) and poikilothermic (earthworms, gastropods, frogs, and fish) animals inhabiting an alluvial backwater area in eastern Austria. With the exception of earthworms, the average concentrations of E. coli and enterococci in the excreta of poikilotherms were equal to or only slightly lower than those observed in homeothermic excreta and were 1 to 4 orders of magnitude higher than the levels observed in the ambient soils and sediments. Enterococci reached extraordinarily high concentrations in gastropods. Additional estimates of the daily excreted SFIB (E. coli and enterococcus) loads (DESL) further supported the importance of poikilotherms as potential pollution sources. The newly established DESL metric also allowed comparison to the standing stock of SFIB in the sediment and soil of the investigated area. In agreement with its biological characteristics, the highest concentrations of C. perfringens were observed in carnivores. In conclusion, the long-standing hypothesis that only humans and homeothermic animals are primary sources of SFIB is challenged by the results of this study. It may be necessary to extend the fecal indicator concept by additionally considering poikilotherms as potential important primary habitats of SFIB. Further studies in other geographical areas are needed to evaluate the general significance of our results. We hypothesize that the importance of poikilotherms as sources of SFIB is strongly correlated with the ambient temperature and would therefore be of increased significance in subtropical and tropical habitats and water resources.IMPORTANCE The current fecal indicator concept is based on the assumption that the standard fecal indicator bacteria (SFIB) Escherichia coli, intestinal enterococci, and Clostridium perfringens multiply significantly only in the guts of humans and other homeothermic animals and can therefore indicate fecal pollution and the potential presence of pathogens from those groups. The findings of the present study showed that SFIB can also occur in high concentrations in poikilothermic animals (i.e., animals with body temperatures that vary with the ambient environmental temperature, such as fish, frogs, and snails) in an alluvial backwater area in a temperate region, indicating that a reconsideration of this long-standing indicator paradigm is needed. This study suggests that poikilotherms must be considered to be potential primary sources of SFIB in future studies.

Original languageEnglish
Article numbere00715-18
JournalApplied and Environmental Microbiology
Volume84
Issue number16
DOIs
Publication statusPublished - 1 Aug 2018

Keywords

  • Animals
  • Animals, Wild/microbiology
  • Bacteria/isolation & purification
  • Bacterial Physiological Phenomena
  • Birds/microbiology
  • Body Temperature Regulation
  • Clostridium perfringens/isolation & purification
  • Ecosystem
  • Environmental Biomarkers
  • Environmental Monitoring
  • Escherichia coli/isolation & purification
  • Feces/microbiology
  • Oligochaeta/microbiology
  • Rivers/microbiology
  • Water Microbiology
  • Mollusk
  • Escherichia coli
  • Clostridium perfringens
  • Earthworm
  • Fishes
  • Poikilothermic
  • Enterococci
  • Frog
  • Excreta
  • Alluvial

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Food Science
  • Biotechnology
  • Ecology

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