Morphology of E. coli

Morphology of E. coli

Morphology of E. coli E. coli is gram-negative (-ve) rod-shaped bacteria. It is 1-3 x 0.4-0.7 µm in size and 0.6 to 0.7 µm in volume. It is arranged singly or in pairs. It is motile due to peritrichous flagella. Some strains are non-motile. Some strains may be fimbriated. The fimbriae are of type 1 … Read more Morphology of E. coli

Habitat of E. coli

Habitat of E. coli

Habitat of E. coli Some of the characteristics are: E. coli was discovered by Theodor Escherich in 1885 after isolating it from the feces of newborns. E. coli is the normal flora of the human body. The niche of E. coli depends upon the availability of the nutrients within the intestine of host organisms. The primary … Read more Habitat of E. coli

Enteropathogenic Escherichia coli (EPEC)

Enteropathogenic Escherichia coli (EPEC)

Enteropathogenic Escherichia coli (EPEC) Two groups of E. coli are responsible for enteric disease: Enteropathogenic E. coli [EPEC] and some Shiga toxin–producing E. coli [STEC]. They both possess a cluster of virulence genes located on a chromosomal pathogenicity island called the locus of enterocyte effacement (LEE). The EPEC are however, defined by: Presence of LEE and Absence … Read more Enteropathogenic Escherichia coli (EPEC)

E. coli Pathotypes- ETEC, EPEC, EHEC, EAEC, EIEC, DAEC

E. coli Pathotypes

E. coli Pathotypes- ETEC, EPEC, EHEC, EAEC, EIEC, DAEC Escherichia coli (commonly abbreviated E. coli) is a Gram-negative, facultative anaerobic, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Human Escherichia coli strains are classified as commensal microbiota E. coli, enterovirulent E. coli, and extraintestinal pathogenic E. coli (ExPEC) on the basis of their genetic features … Read more E. coli Pathotypes- ETEC, EPEC, EHEC, EAEC, EIEC, DAEC

The Wobble Hypothesis

The Wobble Hypothesis

The Wobble Hypothesis There are more than one codon for one amino acid. This is called degeneracy of genetic code. To explain the possible cause of degeneracy of codons, in 1966, Francis Crick proposed “the Wobble hypothesis”. According to this hypothesis, only the first two bases of the codon have a precise pairing with the … Read more The Wobble Hypothesis

Biochemical Test of Escherichia coli (E. coli)

Biochemical Test of Escherichia coli (E. coli)

Biochemical Test of Escherichia coli (E. coli) Basic Characteristics Properties (E. coli) Capsule Capsulated Catalase Positive (+ve) Citrate Negative (-ve) Coagulase Negative (-ve) Flagella Flagellated Gas Positive (+ve) Gelatin Hydrolysis Negative (-ve) Gram Staining Negative (-ve) Growth in KCN Negative (-ve) H2S Negative (-ve) Hemolysis Negative (-ve) Indole Positive (+ve) Motility Motile MR (Methyl Red) … Read more Biochemical Test of Escherichia coli (E. coli)

Acetate Utilization Test- Principle, Procedure and Result Interpretation

Acetate Utilization Test- Principle, Procedure and Result Interpretation

Acetate Utilization Test- Principle, Procedure and Result Interpretation Objective of Acetate Utilization Test To differentiate organisms based on ability to use acetate as the sole source of carbon. Generally used to differentiate Shigella sp. from Escherichia coli. Principle of Acetate Utilization Test This test is used to differentiate an organism capable of using acetate as the sole source … Read more Acetate Utilization Test- Principle, Procedure and Result Interpretation