Identifying and Classifying Microorganisms Ch. 10

Flashcards covering key terms and concepts related to the classification and identification of microorganisms.

Taxonomy

The science of naming organisms and arranging them into hierarchical groups.

Carl Woese

Created the 3 domain system

Phenotypic Traits

Observable characteristics of organisms such as size, shape, and metabolic capabilities.

Genotypic Traits

Characteristics based on the genetic makeup of an organism, including nucleic acid analysis.

Phylogeny

System of arranging species according to evolutionary relatedness in a phylogenetic tree

Serological Testing

Tests that use antibodies to detect specific molecules

MALDI-TOF

A method for rapid identification of microorganisms using mass spectrometry.

Endospore-formers

A group of bacteria that can form thick-walled protective spores, allowing them to survive extreme conditions.

Taxa

Domain-supergroup-kingdom-phylum-class-order-family-genus-species

Classifying Microorganisms (species-prokaryotes)

Grouping of closely related isolates or strains, may be divided into subspecies

Classifying Microorganisms (informal grouping)

Grouping organisms based on shared phenotype or physiology, but are not genetically related

Classifying Microorganisms (historically)

based on phenotypic traits (size, shape, staining, metabolic capabilities)

Three domain system based on

nucleotide sequence in ribosomal RNA

Microscopic morphology (phenotype identification)

determine the size, shape, and staining characteristics of microorganisms

acid fast stain used to identify

mycobacterium tuberculosis

Differential media (phenotype identification)

used to distinguish between different types of microorganisms based on their growth characteristics and metabolic activities.

Streptococcus pneumoniae-pneumonia (differential media)

yeilds a-hemolytic colonies on blood agar (green color due to oxidation of iron in hemoglobin, incomplete rupture)

Streptococcus pyogenes-strep throat (differential media)

yeilds B-hemolytic colonies on blood agar (clear zone around colonies due to complete rupture of red blood cells)

E.coli-urinary tract infection(differential media)

Ferments lactose lowering pH, forms pink colonies on MacConkey agar (pH indicator changes color to pink)

Dichotomous key

A flowchart that generates an identity of a bacterium based on two different outcomes of a number of biochemical tests. Series of alternative questions leading to specific identification.

Catalase test

A biochemical test that identifies bacteria based on their ability to produce the enzyme catalase, which breaks down hydrogen peroxide into water and oxygen, resulting in bubble formation.

Chemical kits

used for rapid identification of microorganisms through various biochemical tests.

Lancefield Grouping

classification system for Streptococcus bacteria, based on specific carbohydrate antigens (sugars) found on their cell walls.

Serotype

a strain that is distinguished by its reactivity with a specific antibody

MALDI-TOF: Time of flight

small ions travel faster than larger ones

Mass spectrum

A “fingerprint” or profile of the proteins and other macromolecules in the cell, computer compares spectrum to database

Kirby-Bauer Disk Diffusion Test

a method to determine the susceptibility of bacteria to antibiotics by observing zones of inhibition around antibiotic-impregnated discs.

Genotype identification

Used to detect specific nucleotide sequences, Nucleic acid amplification test & PCR based test