**Microbiological Quality of River Sediments and Primary Prevention**

 Stefania Marcheggiani and Laura Mancini *Italian- National Institute of Health - Dep Environment and Primary Prevention Viale Regina Elena, Rome Italy* 

#### **1. Introduction**

116 Ecosystems Biodiversity

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> The preservation of aquatic ecosystems is fundamental because water quality, plant and animal biodiversity, industrial activities and human health rely on it. During recent centuries, the condition of aquatic ecosystems has become worse due to the increasing their use for irrigation and drinking, excessive land use and deforestation, hydro morphology alteration, riparian zone reduction and not least, climate change.

> A strong interdependence between the health of the ecosystem and human health can be demonstrated. Microbiological risks for human health can occur through direct or indirect (fish, molluscs, recreational activities, algal bloom, vegetables, fruits) consumption of contaminated water (Tauxe, 1997; UNEP 1997, 1998; Noji, 1997; Ahem *et al.*, 2005). It is a priority to know the quality of the water and manage the data, in this sense it is necessary to identify the main variables that negatively impact human health.

> Indicator organisms are commonly used to evaluate the *microbiological quality* of *aquatic ecosystems (*Berg 1978; Grabow 1996; EU 2006; Tyagi *et al.* 2006)*.* Standard-based water quality assessment is an essential component of monitoring programs and also works to protect human health. As a rule, microbiological indicator detection ( i.e. Enterococci and *Escherichia coli*) take place in the water column as necessitated by national and international laws.

> In this context, it is appropriate underline the important role of sediment on aquatic ecosystems. This matrix is an extremely heterogeneous habitat characterised by a high microbial biodiversity due to the wide range of functional roles that they perform. Its origin is in the weathering and erosion of minerals, organic material, and soils in upstream areas usually after rainfall or the melting of snow. Transported downstream, it settles along the river bed and banks as sedimentation. Sediments consist of particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of water bodies. The suspended particle matter (SPM) which settle by sedimentation, include sediments whose diameter falls between 0.1 and 100 µm. Sediment heterogeneity (e.g. grain-size) in fresh and salt water, creates favorable conditions for biodiversity and is a source of life for a healthy river.

> The particulate matter that plays a specific role in the aquatic ecosystems is the remaining material on a filter with a nominal porosity between 0.4 and 0.5 µm. The material with smaller dimensions is considered as colloidal and/or dissolved. When there have been

Microbiological Quality of River Sediments and Primary Prevention 119

Therefore, the study of sedimentary microbial communities allows the sedimental damage/contamination state or the verification of the potential risk for human health and

A strong correlation between ecosystem health and human health can be demonstrated and many new approaches to monitoring and environmental conduction are possible (Lackey

There are four principle categories of ecosystem functions upon which human health is dependant (De Groot, 1992). The first category contains regulatory functions of ecological processes which deliver water, air, and clean soil through energetic and bio-chemical regulation processes, such as the recycling of organic material. The second category is the supply of space and appropriate substrates for human activities such as cultivation, recreation and living spaces. The third category is the production of numerous resources from which food and basic materials derive. The last category of functions has only an immaterial dimension: ecosystems have a large contribution in maintaining mental equilibrium by delivering opportunities for reflection, spiritual enrichment and aesthetic experience. By employing bioindicators, consisting of organisms or communities of organisms which react to environmental effects by modifying their vital functions, it is possible to draw conclusions on the state of their environment. Due to the complexity of services and resources which are supplied by qualitative and quantitative differentiated ecosystems, it is very difficult to find general indicators that characterize the health of an ecosystem. A rich biodiversity, for example indicates a healthy system, but in some cases it also can be a symptom of disturbance when high amounts of nutrients in an aquatic ecosystem cause the enhancement of growth. An indicator has to be relevant and useful. These properties can be measured by its capacity to measure tendencies with cause of preoccupation, not only by the part of the scientists but also by the public opinion and policymakers. An ecological indicator has to have flexible and measurable characteristics. Because of the dynamics of an ecosystem and the continuous increase of scientific information, an indicator has to be sufficiently extendable to incorporate new ecosystem components. The measurability of an indicator is determined by its disposability and cost, by the capacity to supply alert signals in respect to alteration, by the distribution in a wide geographic area, by the capacity to supply information about a wide set of stresses (Cecchi & Mancini, 2010). It is obvious that it is very difficult to find indicators or groups of indicators that satisfy all the characteristics mentioned above. The current methods of monitoring are studies about: populations, epidemiology, periodic sampling, toxicity tests and chemical analyses. All these techniques have to be used to supply exhaustive evaluations, but overall are not adequate to evaluate the integrity of the ecosystem in a conclusive way. More research is necessary to supply a truly conceptual picture for the

The acquirement of a reliable evaluation of the environmental quality of water bodies is generally the result of the synergic application of different analytical methods mainly including chemio-physical and biological parameters. The degree of contamination is commonly identified by the presence of a microbial community, which can easily proliferate

the need for primary prevention measures to be identified.

definition of objectives for policy makers.

**2.1 Indicators organisms** 

RT, 2001).

**2. Interdependence of ecosystem health and human health** 

found particles with smaller dimensions than this limit, it is not certain if these are the products of aggregates derived from a process of fragmentation during sampling.

The structure and the functions of the microbial communities are strictly linked to the intrinsic peculiarities of the sediment. They are mainly responsible for the recovery of the sediment after the introduction of anthropic perturbations. Microbial processes are highly important for the regeneration of nutrients and nutrient cycles for the whole body of water. To date, estimates suggest that there are up to 104 bacterial species per g sediment, of which at least half (and perhaps as many as 95%) are yet unculturable. There is, therefore, the need to assess the contaminated sediment quality by means of standardised and reliable tools developed by advanced research investigation.

Their complex biochemical diversity enables them to exist in many different habitats everywhere on earth where they are essential for the geochemical cycle and the elimination of many pollutants.

By employing bio-indicators, consisting of organisms or communities of organisms which react to environmental effects by modification of their vital functions, it is possible to draw conclusions on the state of their environment. Due to the complexity of services and resources which are supplied by qualitative and quantitative differentiated ecosystems, it is very difficult to find general indicators that characterize the health of an ecosystem. A rich biodiversity, for example indicates a healthy system, but in some cases it can also be a symptom of disturbance when high amounts of nutrients in an aquatic ecosystem cause enhancement of growth. An indicator has to be relevant and useful.

Sulphate-reducing bacteria are a large group of anaerobic organisms that have an important role in many biogeochemical processes as the sulphur cycle and mineralization of organic matter in anoxic marine and freshwater environments and soil (Sitte *et al.* 2010). The sulphite reducing clostridium group, including *Clostridium perfringens*, has been shown to play an important role to assess faecal pollution in sediment ecosystems (Mancini *et al.* 2010, Marcheggiani *et al.* 2008, Marcheggiani *et al.*, 2004). Their presence can be influenced not only by organic matter but also by inorganic contaminants such as heavy metals (*Mancni et al*., 2011; Mancini *et al.* 2008). *C. perfringens*, gram positive anaerobic spore-forming bacteria of the genus *Clostridum*, that does not carry out a dissimilatory reduction of sulphate, can be used as an alternative indicator for faecal contamination in aquatic ecosystems due to its adaptation to different habitats such as soils, sediments, and sewages . Furthermore*, C. perfringens* presence can be correlated to those of parasitic protozoan and enteric viruses in the water column as *Cryptosporidium sp., Aeromonas sp and Giardia*. In addition, the spores produced by *C. perfringens* are extremely resistant to disinfection and the WHO (1996) suggests that their presence in filtered supplies may be an indication of the need for treatment. Although the World Health Organization recommends *C. perfringens* as a useful indicator of fecal pollution in water quality surveys (WHO, 1978), this microorganism has been adopted in Europe exclusively as an additional source of water quality information (Cabelli , 1978; Olivieri, 1982; Rhodes *et al*., 1999). The sequence of the 16S rRNA gene has been widely used as a phylogenetic marker to study genetic relationships between different strains of bacteria (phylogeny). The analysis of this gene can therefore be considered a standard method for the identification of bacteria at the family, genus and species levels (Woese , 1987; Weisburg *et al*., 1991; Jeng *et al.,* 2001; Lehner *et al.,* 2004; Raju *et al.,* 2006; Johansson *et al.*, 2006), and has in fact been included in the latest edition of *Bergey's Manual of Systematic Bacteriology* (Bergey's Manual, 2005).

found particles with smaller dimensions than this limit, it is not certain if these are the

The structure and the functions of the microbial communities are strictly linked to the intrinsic peculiarities of the sediment. They are mainly responsible for the recovery of the sediment after the introduction of anthropic perturbations. Microbial processes are highly important for the regeneration of nutrients and nutrient cycles for the whole body of water. To date, estimates suggest that there are up to 104 bacterial species per g sediment, of which at least half (and perhaps as many as 95%) are yet unculturable. There is, therefore, the need to assess the contaminated sediment quality by means of standardised and reliable tools

Their complex biochemical diversity enables them to exist in many different habitats everywhere on earth where they are essential for the geochemical cycle and the elimination

By employing bio-indicators, consisting of organisms or communities of organisms which react to environmental effects by modification of their vital functions, it is possible to draw conclusions on the state of their environment. Due to the complexity of services and resources which are supplied by qualitative and quantitative differentiated ecosystems, it is very difficult to find general indicators that characterize the health of an ecosystem. A rich biodiversity, for example indicates a healthy system, but in some cases it can also be a symptom of disturbance when high amounts of nutrients in an aquatic ecosystem cause

Sulphate-reducing bacteria are a large group of anaerobic organisms that have an important role in many biogeochemical processes as the sulphur cycle and mineralization of organic matter in anoxic marine and freshwater environments and soil (Sitte *et al.* 2010). The sulphite reducing clostridium group, including *Clostridium perfringens*, has been shown to play an important role to assess faecal pollution in sediment ecosystems (Mancini *et al.* 2010, Marcheggiani *et al.* 2008, Marcheggiani *et al.*, 2004). Their presence can be influenced not only by organic matter but also by inorganic contaminants such as heavy metals (*Mancni et al*., 2011; Mancini *et al.* 2008). *C. perfringens*, gram positive anaerobic spore-forming bacteria of the genus *Clostridum*, that does not carry out a dissimilatory reduction of sulphate, can be used as an alternative indicator for faecal contamination in aquatic ecosystems due to its adaptation to different habitats such as soils, sediments, and sewages . Furthermore*, C. perfringens* presence can be correlated to those of parasitic protozoan and enteric viruses in the water column as *Cryptosporidium sp., Aeromonas sp and Giardia*. In addition, the spores produced by *C. perfringens* are extremely resistant to disinfection and the WHO (1996) suggests that their presence in filtered supplies may be an indication of the need for treatment. Although the World Health Organization recommends *C. perfringens* as a useful indicator of fecal pollution in water quality surveys (WHO, 1978), this microorganism has been adopted in Europe exclusively as an additional source of water quality information (Cabelli , 1978; Olivieri, 1982; Rhodes *et al*., 1999). The sequence of the 16S rRNA gene has been widely used as a phylogenetic marker to study genetic relationships between different strains of bacteria (phylogeny). The analysis of this gene can therefore be considered a standard method for the identification of bacteria at the family, genus and species levels (Woese , 1987; Weisburg *et al*., 1991; Jeng *et al.,* 2001; Lehner *et al.,* 2004; Raju *et al.,* 2006; Johansson *et al.*, 2006), and has in fact been included in the latest edition of *Bergey's Manual* 

products of aggregates derived from a process of fragmentation during sampling.

developed by advanced research investigation.

*of Systematic Bacteriology* (Bergey's Manual, 2005).

enhancement of growth. An indicator has to be relevant and useful.

of many pollutants.

Therefore, the study of sedimentary microbial communities allows the sedimental damage/contamination state or the verification of the potential risk for human health and the need for primary prevention measures to be identified.
