Introduction to Microbiology

Introduction to Microbiology

• Microbiology is the science of or the study of small life that cannot be seen with the naked eye.
• Microbiology studies living things too small to be seen without magnification.

Importance of Microbiology

• Many microbes are beneficial, performing tasks like recycling essential elements (decomposing organic matter).
• Microbes produce antibiotics and are sources of other nutrients (like vitamin K).
• Some bacteria inhabit human skin, providing protection against pathogens.
• Microbiologists play a key role in fields like medicine (diagnostic labs, research), environmental science, agriculture, and the pharmaceutical industry.

Microbial Taxonomy

• Taxonomy is a biological science encompassing three interconnected disciplines: Classification, Nomenclature (naming), and Identification.
• Classification organizes microorganisms into groups (taxa) based on similar traits (morphological, physiological, and genetic).
• Microorganisms are categorized into domains (Bacteria, Archaea, Eukarya).
• A hierarchy exists with kingdoms, phyla, classes, orders, families, genera, and species. Species names are binomials (genus, species).

Species Examples

• Neisseria gonorrhoeae: Causes gonorrhea (sexually transmitted disease).
• Helicobacter pylori: Causes gastritis and ulcers.
• Neisseria meningitidis: Causes meningitis.
• Escherichia coli strains: Cause food poisoning and urinary tract infections.

Classification Hierarchy (continued)

• Families are formed by adding "-aceae" to the root name of genera.
• Genera contain species sharing common features.
• Each species within a genus differs significantly for classification.
• Species are collections of bacteria sharing physiological and genetic characteristics and differing noticeably from other species.
• Taxonomic subgroups below species include subspecies (with categories like biotype, serotype, or genotype), where organisms with similar antigens form a serogroup. Subspecies within groups have specific characteristics but differ relatively from other subgroups.

Pseudomonas Comparison

• Pseudomonas aeruginosa and Pseudomonas fluorescens are two examples of bacteria, differentiated by visual analysis of their growth on a petri dish.

Microbial Identification Methods

• Microbial identification is the process of characterizing microorganisms, encompassing phenotype and genotype approaches.
• Phenotype-based methods use observable characteristics like macroscopic morphology (colony appearance), microscopic morphology, staining characteristics (Gram stain), environmental requirements (temperature, pH, oxygen), and nutritional requirements.
• Genotype-based methods examine genetic characteristics including DNA base composition ratios (G+C content), nucleic acid (DNA/RNA) base sequence analysis (including hybridization assays).

Nomenclature

• Microorganisms are named according to established rules of the International Code of Nomenclature of Bacteria, or Bacteriological Code.
• Scientific names consist of genus and species names. The genus name (always capitalized) is followed by the species name (always lower case). Examples include Streptococcus pneumoniae (abbreviated as S. pneumoniae).