Coliform vs. Fecal Coliform

Attribute	Coliform	Fecal Coliform
Definition	Coliform bacteria are a group of bacteria that are commonly found in the environment, including the intestines of warm-blooded animals. They are used as indicators of water quality and the presence of fecal contamination.	Fecal coliform bacteria are a subgroup of coliform bacteria that specifically originate from the intestines of warm-blooded animals. Their presence in water indicates recent fecal contamination and potential health risks.
Origin	Coliform bacteria can be found in various environmental sources such as soil, vegetation, and water. They can also be present in the intestines of animals and humans.	Fecal coliform bacteria originate exclusively from the intestinal tracts of warm-blooded animals, including humans, and are excreted in feces.
Indicator of Fecal Contamination	Coliform bacteria serve as general indicators of water quality and the potential presence of fecal contamination. Their presence suggests a higher likelihood of harmful pathogens being present.	Fecal coliform bacteria are more specific indicators of recent fecal contamination. Their presence indicates a higher risk of harmful pathogens and potential health hazards.
Testing Methods	Coliform bacteria are typically detected using the multiple tube fermentation (MTF) or membrane filtration (MF) methods. These methods provide a general count of coliform bacteria present.	Fecal coliform bacteria are specifically identified using the membrane filtration (MF) method. This method differentiates fecal coliforms from other coliform bacteria and provides a count of fecal coliform colonies.
Regulatory Standards	Coliform bacteria are regulated by various water quality standards and guidelines worldwide. Their presence above certain limits may indicate the need for further investigation or treatment.	Fecal coliform bacteria are specifically regulated by water quality standards due to their association with recent fecal contamination and potential health risks. Their presence above certain limits may require immediate action to ensure water safety.

Introduction

Coliform and fecal coliform are terms commonly used in microbiology and environmental science to describe groups of bacteria that serve as indicators of water quality and potential fecal contamination. While both types of bacteria belong to the same family, they have distinct characteristics and play different roles in assessing water safety. In this article, we will explore the attributes of coliform and fecal coliform, highlighting their differences and significance in water quality monitoring.

Coliform Bacteria

Coliform bacteria are a broad group of bacteria that are commonly found in the environment, including soil, vegetation, and the intestines of warm-blooded animals. They are gram-negative, rod-shaped bacteria that are facultative anaerobes, meaning they can survive in both aerobic and anaerobic conditions. Coliform bacteria are non-pathogenic, meaning they do not typically cause disease in humans. However, their presence in water can indicate the potential for fecal contamination and the possible presence of other harmful pathogens.

Coliform bacteria are characterized by their ability to ferment lactose, a sugar found in milk and dairy products. This ability is often used as a key indicator in water quality testing. The most commonly used test to detect coliform bacteria is the presence-absence test, which involves incubating water samples in a selective medium that promotes the growth of coliform bacteria. If coliform bacteria are present, they will produce gas and acid as byproducts of lactose fermentation, causing a color change in the medium.

It is important to note that not all coliform bacteria are of fecal origin. Some coliform bacteria can be naturally present in the environment, while others may originate from non-fecal sources such as plants or soil. Therefore, the presence of coliform bacteria alone does not necessarily indicate the presence of fecal contamination or harmful pathogens.

Fecal Coliform Bacteria

Fecal coliform bacteria are a subset of coliform bacteria that are specifically associated with the intestines and feces of warm-blooded animals. They are considered a more specific indicator of fecal contamination and the potential presence of enteric pathogens, which are bacteria that cause gastrointestinal illnesses. Fecal coliform bacteria are also gram-negative, rod-shaped, and facultative anaerobes, similar to coliform bacteria.

Unlike coliform bacteria, fecal coliform bacteria are characterized by their ability to ferment lactose at elevated temperatures, typically around 44.5°C (112.1°F). This higher temperature requirement distinguishes fecal coliform bacteria from other coliform bacteria that may be present in the environment. The most commonly used test to detect fecal coliform bacteria is the multiple tube fermentation (MTF) test, which involves inoculating water samples into tubes containing a lactose broth and incubating them at the elevated temperature. The presence of gas production in the tubes indicates the presence of fecal coliform bacteria.

Since fecal coliform bacteria are more closely associated with fecal contamination, their presence in water is considered a stronger indication of potential health risks. The presence of fecal coliform bacteria suggests that the water may have been contaminated with fecal matter, which can contain harmful pathogens such as Escherichia coli (E. coli) and Salmonella. Therefore, the detection of fecal coliform bacteria in water samples often triggers further investigation and potential remediation measures to ensure water safety.

Significance in Water Quality Monitoring

Both coliform and fecal coliform bacteria play crucial roles in water quality monitoring and assessing the safety of water sources. The presence of coliform bacteria in water samples is an indication of potential fecal contamination and the possible presence of other harmful pathogens. It serves as a warning sign that further investigation is needed to determine the source and extent of contamination.

On the other hand, the presence of fecal coliform bacteria specifically indicates a higher likelihood of fecal contamination and the potential presence of enteric pathogens. This distinction makes fecal coliform bacteria a more reliable indicator of waterborne diseases and the need for immediate action to protect public health.

Water quality standards and regulations often set limits for both coliform and fecal coliform bacteria in drinking water supplies. The presence of either type of bacteria above the permissible limits can trigger the implementation of treatment processes or the issuance of boil water advisories to ensure the safety of the water before consumption.

Conclusion

Coliform and fecal coliform bacteria are important indicators of water quality and potential fecal contamination. While both types of bacteria belong to the same family and share some characteristics, they have distinct attributes that differentiate them in terms of their origin, detection methods, and significance in water quality monitoring. Coliform bacteria serve as a general indicator of potential fecal contamination, while fecal coliform bacteria specifically indicate a higher likelihood of fecal contamination and the potential presence of enteric pathogens. Understanding the attributes of these bacteria is crucial for effective water quality management and ensuring the safety of water supplies.