The fecal contamination of water bodies may pose serious risks to humans and ecological systems since it introduces organic matter, nitrogen, phosphorous as well as potential pathogenic microorganisms. It represents a threat to health and can cause environmental degradation and economic losses; this is particularly true for drinking water supplies, recreational water bodies, and shellfish harvesting waters. Since the contamination by enteropathogens has been frequently reported in different aquatic ecosystems, the rapid and reliable identification of the origins of pollution is extremely relevant to facilitate water quality management, remediation strategies, and health risk assessments. Microbial source tracking (MST), which encompasses a suite of tools that enable the tracing of certain enteric microorganisms to a particular host, has been widely applied for the identification of fecal sources in diverse environments. It may represent an effective instrument for the evaluation of the impact of microbial pollution on the environment and human health.

Waterborne pathogens represent a significant public health concern and can place a heavy burden of disease on exposed communities. Many of these microorganisms can result in death especially in children and immunocompromised individuals such as Human Immunodeficiency Virus/Acquired Immune Deficiency Syndrome (HIV/AIDS) infected patients or cause outbreaks. Contributing to this is the emergence of antimicrobial resistance and the spread of antibiotic resistant bacteria that have been described as one of the major threats to individual and population health in the 21st century. The propagation of antimicrobial resistance was considered to be limited to clinical environments, however, there is a growing realization that it is also associated with anthropogenically impacted environmental sources. Fecal contamination of water environments plays a critical role as reservoirs of these pathogens require continuous monitoring and surveillance to determine the potential public health risks to communities. To handle these threats efficiently and comprehensively, increasingly direct and rapid approaches to water quality monitoring are favored.

Usually, fecal water contamination is monitored using very simple and cost-effective methods for the detection and the enumeration of the so-called fecal indicator bacteria (FIB), such as Escherichia coli and Enterococcus spp., which are considered as the primary microbiological parameters to assess the quality of water. However, the examination of fecal indicator bacteria does not accurately elucidate the potential sources of contamination, due to the low host specificity. MST is used to identify sources of fecal pollution through the detection of host-specific microorganisms or genetic signatures and, to date, many molecular markers have been identified and exploited for the attribution of the polluting source in various aquatic ecosystems. In addition, the use of diverse phenotypic and genotyping methods, including whole genome sequencing and metagenomics, may enable researchers to elucidate the potential environmental and public health risks of the microbial pathogens circulating in contaminated water systems.

The main aim of this Research Topic is to collect the most recent studies focused on genetic marker-based MST investigations carried out in different freshwater environments in order (1) to provide an up-to-date picture of the knowledge currently achieved in the field and (2) to highlight those issues that must be addressed for the further advancement of these technologies in environmental research.

The present call for papers invites researchers who deal with microbiological water pollution issues, specially focused on the use of microbial source tracking technologies to identify the origin of fecal contamination. The collection may include original research articles, brief research reports, methods articles, reviews, mini reviews, perspectives, and opinion articles.

The Editors will also consider those contributions focused on the issues related to the standardization of MST operating procedures (e.g., collection of a sample and its preservation, microbial DNA extraction methods, and PCR/qPCR protocols for the detection of the molecular markers) useful for the cross-laboratory and -Country data comparison and the improvement of MST technologies and their applications.

Impact

Frontiers in Water

Environmental Water Quality

Water and Human Health