Difference Between E Coli and Coliform

The main difference between E coli and coliform is that the E. coli are a type of bacteria; that is, a fecal coliform whereas the coliform is a bacterium involved in the fermentation of lactose when incubated at 35–37°C. The other type of coliform bacteria is non-fecal coliforms that are Enterobacter and Klebsiella. Fecal coliforms live inside the intestine of warm-blooded animals while non-fecal coliforms live free in the soil. 

E. coli and Coliform are rod-shaped, non-spore producing Gram-negative bacteria. They can be either motile or non-motile. 

Key Areas Covered 

1. What is E Coli
     – Definition, Facts, Importance
2. What is Coliform
     – Definition, Facts, Importance
3. What are the Similarities Between E Coli and Coliform
     – Outline of Common Features
4. What is the Difference Between E Coli and Coliform
     – Comparison of Key Differences

Key Terms 

Coliform, E. coli, Fecal Coliforms, Non-Fecal Coliforms

What is E Coli 

E. coli (Escherichia coli) is a type of non-coliform bacteria that can be mainly found in the fecal matter of warm-blooded animals. It is a commensal in the intestine of those animals. The presence of E. coli in drinking water is considered an extreme health hazard since E. coli can cause diseases in humans. The common symptoms of those diseases caused by E. coli are the fever, abdominal cramps, and diarrhea. The victims are mainly elderly persons, children, and those who are immunocompromised. The contaminated drinking water can be primarily treated by boiling water for at least one minute.  

Figure 1: Relationship between E. coli and Coliform

What is Coliform 

Coliform is a group of bacteria including around 18 bacterial species, which indicates the sanitary quality of the drinking water. Generally, coliform is non-pathogenic bacteria that do not cause diseases. However, the presence of coliform in drinking water gives the hint that pathogenic bacteria may also enter that particular drinking water source along with the contamination of sewage. On that account, coliforms in drinking water are considered a potential health hazard for human consumption. The laboratory tests results indicate either ‘coliform present’ or ‘coliform absent’. The samples classified as ‘coliform absent’ do not contain a single coliform. But, ‘coliform present’ means that coliform bacteria are present in the sample; this bacteria can be either E. coli or another type of coliform. The first method of removing coliform from drinking water is the shock chlorination. Then, chlorine is washed from 5-7 days and water is retested for the presence of coliforms. 

Figure 2: Coliform from a Water Sample

Th most significant feature of coliform is its ability to ferment lactose, producing an acid and a gas. The two types of coliforms are fecal coliforms and non-fecal coliforms. Fecal coliforms ferment lactose at 44 °C while non-fecal coliforms ferment at 37 °C. The typical genera of coliforms are Citrobacter, Enterobacter, Hafnia, Klebsiella, and Escherichia.  

Similarities Between E Coli and Coliform 

• E. coli and coliform are two types of rod-shaped Gram-negative bacteria. 
• They do not produce spores. 
• They are either motile or non-motile. 
• Both live free in the environment or inside the intestine of warm-blooded animals. 
• Both can ferment lactose, producing an acid and a gas. 

Difference Between E Coli and Coliform 

Definition 

The E. coli refers to a bacterium commonly found in the intestines of humans and other animals, some strains of which can cause severe food poisoning while the coliform refers to a group of rod-shaped bacteria typified by E. coli.  

Type

E. coli is a fecal coliform that lives inside the intestine of warm-blooded animals while coliform can be either fecal coliforms or non-fecal coliforms that live in the soil. 

Type of contamination 

The presence of E. coli in drinking water indicates a fecal contamination while the presence of coliforms in drinking water indicates an environmental contamination. 

Importance 

The drinking water with E. coli is considered as ‘extreme health hazard’ while the drinking water with coliform is considered as ‘potential health hazard’.  

Lactose Fermentation 

Optimal temperature for the lactose fermentation in fecal coliforms like E. coli is 44°C while the optimal temperature for the lactose fermentation in non-fecal coliforms is 37 °C. 

On the selective mFC medium

E. coli like fecal coliforms form dark-blue colonies while non-fecal coliforms form pink colonies. 

Conclusion 

E. coli is a type of fecal coliform that lives in the intestine of warm-blooded animals while coliform is a group of bacteria that ferment lactose. The presence of E. coli indicates a fecal contamination, which is an extreme health hazard while the presence of coliform indicates an environmental contamination, which is a potential health hazard. The main difference between E. coli and coliform is the type of bacteria and their health effect. 

Reference:

1. “Interpreting Coliform Bacteria Test Results.” Neilson Research Corp., Available Here

Image Courtesy:

1. “Coliforme – ENDO agar” By Matthias M. – Own work (CC BY-SA 3.0) via Commons Wikimedia