Nomenclature and Bergeys manual

Nomenclature in Microbiology

Nomenclature = the system of naming microorganisms in a standardized way so scientists worldwide can communicate clearly.

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a) Binomial System (developed by Linnaeus, adopted in microbiology)

• Each organism has two names:
  • Genus (capitalized, italicized/underlined).
  • Species (lowercase, italicized/underlined).
• Example: Escherichia coli (italicized).

b) Rules of Nomenclature

• Governed by the International Code of Nomenclature of Prokaryotes (ICNP).
• Names are usually derived from Latin or Greek roots, based on morphology, habitat, or to honor a scientist.
  • Staphylococcus aureus → “golden grape-like cluster.”
  • Salmonella → named after Daniel Elmer Salmon.
• Abbreviations: E. coli (after first mention).
• Newly discovered organisms are published in the journal International Journal of Systematic and Evolutionary Microbiology (IJSEM) for official approval.

c) Strain Designation

• Within a species, different strains may exist.
• Identified by letters/numbers after species name, e.g., E. coli K12, Bacillus subtilis 168.

2. Bergey’s Manual of Systematic Bacteriology

Bergey’s Manual is the authoritative reference for bacterial classification and identification.

a) History

• Named after David Hendricks Bergey (1860–1937).
• First published in 1923 as Bergey’s Manual of Determinative Bacteriology.
• Later expanded into Bergey’s Manual of Systematic Bacteriology (multi-volume).

b) Purpose

• Provides a comprehensive and systematic description of all recognized prokaryotic taxa.
• Based on morphological, physiological, biochemical, ecological, and molecular characteristics.
• Serves as the “bacterial bible” for microbiologists.

c) Structure of Bergey’s Manual

• Organizes bacteria according to phylogeny (evolutionary relationships) and taxonomy.
• Classification based heavily on 16S rRNA gene sequencing and molecular systematics.
• Divides prokaryotes into:
  • Domain Bacteria
  • Domain Archaea
• Each domain is subdivided into phyla, classes, orders, families, genera, and species.

d) Key Features

• Provides identification keys for bacterial isolates.
• Includes descriptions of:
  • Cell morphology.
  • Gram reaction.
  • Motility and spore formation.
  • Metabolic/biochemical properties.
  • Molecular characteristics.
  • Ecological significance.

e) Two Versions

1. Bergey’s Manual of Systematic Bacteriology → For taxonomy and classification (multi-volume reference).
2. Bergey’s Manual of Determinative Bacteriology → For laboratory identification (practical diagnostic tool, more concise).

3. Significance

• Standardization: Provides uniform naming and classification worldwide.
• Clinical microbiology: Essential for identification of pathogens.
• Research: Helps in characterizing new isolates.
• Industrial and environmental microbiology: Guides selection of microbes for biotechnology, waste treatment, agriculture.