Persistence and Decay of Fecal Microbiota in Aquatic Habitats
Citation:
Korajkic, A., P. Wanjugi, L. Brooks, Y. Cao, AND V. Harwood. Persistence and Decay of Fecal Microbiota in Aquatic Habitats. Microbiology and Molecular Biology Reviews. American Society for Microbiology, Washington, DC, 83(4):e00005-19, (2019). https://doi.org/10.1128/MMBR.00005-19
Impact/Purpose:
This review article describes the effect of various biotic and abiotic environmental factors on decay of different indicators of fecal pollution and enteric pathogens.
Description:
Fecal microorganisms can enter water bodies in diverse ways, including runoff, sewage discharges and direct fecal deposition. Once in water, these microorganisms experience conditions that are very different from their original intestinal habitats. The transition from host to aquatic environment may lead to rapid inactivation, some degree of persistence, or growth, depending upon the organism and the habitat. Microorganisms may remain planktonic, be deposited in sediment, wash up on beaches, or attach to aquatic vegetation. Each of these habitats offers a panoply of different stressors or advantages, including ultraviolet light exposure, temperature fluctuations, salinity, nutrient availability and biotic interactions with indigenous microbiota (e.g. predation and/or competition). The host sources of fecal bacteria, viruses, and protozoa are likewise numerous, ranging from wildlife, to pets and livestock, and humans. Most of these microorganisms are of little concern to human health, but certain taxa are pathogenic, including Escherichia coli O157:H7, Salmonella enterica, Campylobacter jejuni, enteric viruses and pathogenic protozoa species. Others are used as warning signals of pathogen presence, such as fecal indicator bacteria (e.g. E. coli and enterococci) and bacteriophages (e.g. somatic and F+ coliphage) or as fecal source identifiers (microbial source tracking markers). The effects of environmental factors are frequently inconsistent across microbial species, fecal source(s), and the measurement strategy employed (e.g. culture vs molecular). As a result, broad generalizations about the fate of fecal microbiota in aquatic environments are generally erroneous, compromising efforts to predict microbial decay and health risk from contamination events. This review summarizes the recent literature on decay of fecal microorganisms in aquatic environments, recognizes defensible generalizations, and identifies knowledge gaps that may provide particularly fruitful avenues for obtaining a better understanding of the fate of these organisms in aquatic environments.
