SABS I Lecture 4: Bacterial Classification

- Streptococcus mutans

- gram positive

- facultative anaerobe

What is the primary microbe responsible for caries in the oral cavity? It is gram negative or positive? What is the type of bacteria?

type strain

one strain of a species; serves as the permanent reference specimen for the species

phylotype

term used for bacteria that are unculturable (cannot be grown in a lab)

16SrRNA

the phylotype is used for uncharacterized microbes for while only _________ gene sequence data are avaliable

traditional methods (physical traits)

The phylotype cannot be classified by which methods?

2% (approximately 30 bp for 16S rRNA)

The phylotype designation applies if the DNA sequence of the gene differs from known species by how much?

97%

members of a phylotype share at least _________ similarity of their DNA with each other

phenotypic taxonomy (pre-genetics)

traditional method of characterization and identification; requires that bacteria can be cultured in a lab

genotypic taxonomy

distinguishes closely related organisms (often in addition to phenotypic traits) using their DNA or RNA, and not observable traits to classify them

identify different taxa (diversity) in a bacterial community

What does genotypic taxonomy helps to do?

- shape

- size

- structural arrangement (microscopic and macroscopic)

- cellular structures

What does morphology consist of?

- cell shape

- spore formation and spore location

- Gram stain

- motility

- flagella

- fimbriae

Examples of morphology

0.5-1 um

smallest bacteria length

up to a few um

largest bacteria length

- rod

- coccus

- spiral

basic shapes of bacteria

shape

What is the first classification phenotypically?

- shape variations

- associations

phenotypic morphology types

- regular

- irregular

shape variations of cocci

- short

- long

- curved

- bent

- pleomorphic

- ends pointed, round, or flat

shape variations of rods

- bends

- spiral

other shape variations besides cocci and rods

- chains

- clusters

(regular, irregular)

types of phenotypic morphology associations

chains

"strepto" means

clusters (that look like grapes)

"staphylo" means

rod-shaped

bacillus means

bacillus

What would this be known as?

diplobacillus

What would this be known as?

streptobacillus

What would this be known as?

coccobacillus

What would this be known as?

coccus

What would this be known as?

diplococcus

What would this be known as?

streptococcus

What would this be known as?

tetrad

What would this be known as?

staphylococcus

What would this be known as?

sarcina

What would this be known as?

positive, leftover sugars (saccrolytic), lactic acid (acidogenic), 4.5-5, secondary, low, CO2, oxygen (facultative anaerobe)

streptococcus mutans info:

gram _________ feeds on _______ _________ and creates ________ __________ and can tolerate pH _______. __________ colonizer which is associated with caries. best in _______ oxygen or extra _______, can grow without ________.

primary colonizers

type of colonizer that attaches to healthy, clean tooth; "the good guys"

staphylococcus aureus

gram positive bacteria found only temporarily in the oral cavity; colonizes the skin

negative, facultative anaerobe, critically ill

Escherichia coli is a gram _________ bacteria that is a ___________ ___________ (type) not found in healthy dental plaque but can be found in ________ ________ patients

Escherichia coli

Rods are always compared to which bacteria?

positive, rod (branching bacilli), capnophilic, obligate anaerobe, oral surgeries

Actinomyces israelii is a gram _________ bacteria that is a _________ (shape), __________, _____________ _________ (type) but can tolerate microaerophile conditions. It is usually harmless but can be an issue with ______ ________

negative, obligate anaerobe, opportunistic, acidgenic, capnophilic, aciduric

Fusobacterium nucleatum is a gram _______ bacteria that is a ________ _________ (type) in dental plaque. It is an __________ pathogen, so it helps build biofilm by sticking different bacteria together. It is not _______ nor ________ but it is _________ (refering to what it likes/capabilities)

vibrio

What would this be known as?

spirillum

What would this be known as?

spirochete

What would this be known as?

- oxygen requirements

- growth temperature

- pH tolerance

- Carbon and nitrogen sources used

- metabolic product formation

- special nutritional requirements (vitamins, iron, etc.)

physiology/biochemistry components of bacterial classification

- cell wall and outer membrane components

- protein profile

chemical composition requirements of bacterial classification

genotypic taxonomy

used for distinction between closely related genera, species, and strains

- polymerase chain reaction

- next-generation sequencing

- '-omics' (genomics, transcriptomics, proteomics, metabolomics)

current molecular biology techniques for genotypic taxonomy include

genomes or single genes (16S rRNA gene)

current molecular biology techniques are used to either compare

microscopy, culture, biochemical tests, molecular tests

simplified scheme for bacterial identification

- gram stain

- shape

- motility

microscopy portion of bacterial identification

growth conditions (nutrients, oxygen requirements, etc.)

culture portion of bacterial identification

- composition of cell wall

-metabolomics

biochemical tests portion of bacterial identification

16S rRNA sequencing

molecular tests portion of bacterial identification