Indicator Organism in wastewater treatment

 Source - Science direct 

Indicator organisms have been used as markers whose presence in numbers exceeding given numerical limits indicates the possible occurrence of ecologically similar pathogens, inadequate processing, and the quality of raw materials. The term ‘indicator organisms’ has been used for nearly a century to assess the microbiological status of food production and food control systems, including evaluating the quality or safety of raw or processed food products and validating the effectiveness of microbial control measures.

Indicator organisms are microorganisms such as bacteria and viruses in water bodies, which are utilized as a surrogate to evaluate the presence of pathogens in that environment. These microorganisms are preferred to be nonpathogen, have no or minimal growth in water, and reliably detectable at low concentrations.

Indicator organisms are considered normal flora (always present) in the digestive system of all warm-blooded animals, including humans. The detection of indicator organisms suggests that enteric pathogenic microorganisms may also be present due to the fecal contamination.

Foodborne disease and microbial spoilage of food result from the failure or inability to control the contaminants, such as foodborne pathogens, food spoilage organisms, indicator organisms or microbial toxins in one or more stages of the food chain, from raw material to consumption. The most conventional methods for detecting foodborne bacterial pathogens in food and other substrates depend on the use of microbiological media to selectively grow and enumerate bacteria. The methods are sensitive, generally inexpensive, and provide qualitative as well as quantitative results. Unfortunately, for the food industry in which time and cost are important issues, the preparation of media and plates, as well as colony counting and biochemical characterization of the isolated colonies is a time-consuming and labor-intensive process. The examination of a food product for indicator organisms can provide simple, reliable, and rapid information about processing failure, postprocessing contamination from the environment, the general level of hygiene and presence or absence of foodborne pathogen. Many indicator analyses normally involve the estimation of number of organisms in the food. These analyses cannot replace the examination for specific pathogens for which suitable methods exist and for which such analysis is appropriate, but they usually can provide information in a shorter time than that required for isolation and identification of specific organisms or pathogens. Thus, indicator analyses are used widely to measure improper sanitation. Additionally, they also could be used to monitor adherence to good manufacturing practice (GMP)/good hygiene practice (GHP) and hazard analysis critical control point. The use of indicators is highly dependent on the microbiological criteria according to national and international microbiological criteria (i.e., Codex Alimentarius) that are in place for the food product.

Surrogate microorganisms, which are functionally distinct from indicator organisms, are invaluable in validating the efficacy of interventions and control processes. Their use, as opposed to using actual pathogens, derives from the need to prevent the introduction of harmful organisms into the production facility. To obtain quantitative information to support the development and validation of interventions and control processes, it is necessary to use microbial surrogates. They are used in a different way than indicator organisms, and the difference is discussed in this article.

The challenges to the use of indicators to ensure the safety and quality of products and surrogates to determine the effectiveness of the microbial reduction treatment.