Water-borne pathogen contamination in water resources and related diseases are a major water quality concern throughout the world. Increasing interest in controlling water-borne pathogens in water resources evidenced by a large number of recent publications clearly attests to the need for studies that synthesize knowledge from multiple fields covering comparative aspects of pathogen contamination, and unify them in a single place in order to present and address the problem as a whole. Providing a broader perceptive of pathogen contamination in freshwater (rivers, lakes, reservoirs, groundwater) and saline water (estuaries and coastal waters) resources, this review paper attempts to develop the first comprehensive single source of existing information on pathogen contamination in multiple types of water resources. In addition, a comprehensive discussion describes the challenges associated with using indicator organisms. Potential impacts of water resources development on pathogen contamination as well as challenges that lie ahead for addressing pathogen contamination are also discussed.

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Contamination of water resources by pathogenic bacteria

Erodibility of cohesive sediment: The importance of sediment properties

There is increasing evidence that consumption of raw fresh produce is a major factor contributing to human gastrointestinal illness A wide variety of pathogens contribute to food-borne illnesses, including bacteria (eg, Salmonella, pathogenic Escherichia coli), protozoa (eg, Cryptosporidium, Giardia), and viruses (eg, noroviruses) Large-scale production of produce typically requires some form of irrigation during the growing season There is a rapidly growing body of research documenting and elucidating the pathways of produce contamination by water-borne pathogens However, many gaps still exist in our knowledge and understanding The purpose of this review is to provide a comprehensive approach to the issue, including the most recent research Topics covered include: temporal and spatial variability, and regional differences, in pathogen and indicator organism concentrations in water; direct and circumstantial evidence for contaminated water as a source of food-borne pathogens; fate and transport of pathogens and indicator organisms in irrigation systems, and the role of environmental microbial reservoirs; and current standards for irrigation water quality, and risk assessment A concerted effort by researchers and practitioners is needed to maintain food safety of fresh produce in an increasingly intensive food production system and limited and declining irrigation water resources

https://pubag.nal.usda.gov/pubag/downloadPDF.xhtml?id=55092&content=PDF

Irrigation Waters as a Source of Pathogenic Microorganisms in Produce

There is increasing evidence that consumption of raw fresh produce is a major factor contributing to human gastrointestinal illness. A wide variety of pathogens contribute to foodborne illnesses, including bacteria (e.g., Salmonella, pathogenic Escherichia coli), protozoa (e.g., Cryptosporidium, Giardia), and viruses (e.g., noroviruses). Large-scale production of produce typically requires some form of irrigation during the growing season. There is a rapidly growing body of research documenting and elucidating the pathways of produce contamination by waterborne pathogens. However, many gaps still exist in our knowledge and understanding. The purpose of this review is to provide a comprehensive approach to the issue, including the most recent research. Topics covered include temporal and spatial variabilities, and regional differences, in pathogen and indicator organism concentrations in water; direct and circumstantial evidence for contaminated water as a source of foodborne pathogens; fate and transport of pathogens and indicator organisms in irrigation systems, and the role of environmental microbial reservoirs; and current standards for irrigation water quality and risk assessment. A concerted effort by researchers and practitioners is needed to maintain food safety of fresh produce in an increasingly intensive food production system and limited and declining irrigation water resources.

Irrigation Waters as a Source of Pathogenic Microorganisms in Produce: A Review

Bacteria may be critical for the functionality, associated productivity, and risk profile of wastewater based algal systems. Both wastewaters and algal stocks act as sources of bacteria effectively creating a tripartite system where it is reasonable to expect interactions between algae, bacteria from wastewater, and algae associated bacteria. The functionality associated with this complex system will be critically derived from the synergistic activities of its biological members, which in turn will be affected by the induced trophic status of the very same system. It is critical that, as algal biofuel research expands into large-scale cultivation trials and production, these interactions and associated functions are assessed, monitored, and considered when management options are being developed.

Mini-review: A priori considerations for bacteria–algae interactions in algal biofuel systems receiving municipal wastewaters

The transport and fate of indicator E. coli and Salmonella are shown to be highly influenced by their relationship with flocculated suspended and bed sediment particles. Flocs were found to dominate the suspended sediment load and have the effect of increasing the downward flux of the sediment to the river bed. Bacteria counts were consistently higher within sediment compartments (suspended and bed) than for the water alone, with the bed sediment found to represent a possible reservoir of pathogens for subsequent remobilization and transport to potentially high risk areas. The mechanism of microbial attachment and entrapment within the sediment was strongly linked to the EPS fibrils secreted by the biological consortium of the aquatic system. It is suggested that the sediment/pathogen relationship should be of concern to public health officials because of its potential effects on pathogen source fate and effect with implications on public health risk assessment. Current standard sampling strategies, howev...

Dynamic Existence of Waterborne Pathogens within River Sediment Compartments. Implications for Water Quality Regulatory Affairs

Experiments were conducted in an annular flume using waste bed sediment from a discontinued aquaculture operation to assess its stability against erosion. Critical shear stress for erosion was measured under different flow conditions and after three different consolidation periods (2, 7 and 14 days). The influence of biostabilization was also assessed as a mechanism for controlling the bed sediment stability. Results suggest a moderate increase in bed sediment strength with time as evidenced by the increasing critical bed shear stress for erosion with increasing consolidation times. Critical bed shear stress for erosion ranged from 0.06 to 0.1 Pa. Eroded floc size and settling velocities were in the range that would allow for significant horizontal transport of sediments provided a flow was present (i.e. transport outside of the aquaculture pens). The increase in sediment strength with time is believed to be more strongly influenced by biofilm integration on and within the surface sediment layer than to consolidation and dewatering effects. Extensive biofilm growth was visibly evident and microscopy confirmed the presence of extensive filamentous organisms (likely of a fungal origin) and bacteria. The point of failure of this biostabilized sediment was significantly lower than that reported for other natural freshwater and salt water sediments. Regardless of the sediment type, however, biostabilization is a consistent and important mechanism which controls the stability of sediments. Factors such as the microbial community and sediment floc structure will need to be considered in order to improve our understanding of the mechanisms of bed sediment stability and erosion for the environmentally sustainable operations of aquaculture facilities.

Chris Jaskot

Papers

Dynamic Existence of Waterborne Pathogens within River Sediment Compartments. Implications for Water Quality Regulatory Affairs

Aquaculture Waste Sediment Stability: Implications for Waste Migration