Acetate Utilization Test- Principle, Procedure, Results, Uses

Acetate Utilization Test- Principle, Procedure and Result Interpretation

What is Acetate Utilization Test? The acetate utilization test is one of the biochemical tests performed for the identification of aerobic organisms by evaluating their ability to utilize acetate present in the growth media. The principle of the acetate utilization test is based on the ability of an organism to utilize acetate as a sole source of carbon. This test …

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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 (hemagglutinating & mannose-sensitive) and are …

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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 habitat of E. coli is in …

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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 of Shiga toxin. Enteropathogenic Escherichia coli (EPEC), one of …

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

E. coli Pathotypes

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 and clinical outcomes. Most infections (with the exception of neonatal meningitis and gastroenteritis) are …

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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 bases of the anticodon of tRNA, while the …

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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) Positive (+ve) Nitrate Reduction Positive …

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