Prokaryotic Diversity

MCB4403

Archaea

a very diverse domain of life

are prokaryotes

Archea prokaryotes similarities to bacteria

• aerobes and anaerobes

• autotrophs and heterotrophs

• gram positive and negative

• normally 1 circular chromosome

Archea prokaryotes diffrences to bacteria

• difference in 16S rRNA sequences

• do NOT have peptidoglycan

• chromosomes have histones (like eukaryotes)

• role as human pathogen is unclear but they are part of human microbiome

extra archaea information

some are extremophiles or psychrophiles, found everywhere but difficult to culture

what phylum is believed to be where eukaryotes evolved from

Hemidallarchaeota

Bacterial Phyla largest to smallest

1. bacteria (domain)

2. proteobacteria (phylum)

3. gammaproteobacteria (class)

4. enterobacterales (order)

5. enterobacteriaceae (family)

6. escherchia (genus)

7. coli (species)

how are they places into bacterial phyla

phylogenetics is based on 16s rRNA sequencing

not based on trait/phenotypes

can resolve down to species level

undiscovered bacteria because

most-ish species are uncharacterized because they can’t be grown in culture so it makes them hard to identify

Identify unclassified organisms

identified solely through ribosomal DNA gene sequence

Uncharacterized bacteria environmental samples

rDNA is sequenced, can sometimes give provisional identification

what are the prokaryotic breakdown (tree)

1. prokaryotic

2. Peptidoglycan rRNA signature or Pseudomurein rRNA signature

3. psuedo next is Domain Archaea (end)

3. Peptid next is domain bacteria

4. gram negative or gram positive

5. gram negative next is proteobacteria or nonproteobacteria

5. gram positive next is low G+C or high G+C

Gram positive phyla

small group compared to (-)

a lot are harmful so hard to grow

only have 3 known phyla

• firmicutes

• actinobacteria

• tenericutes

most are chemoheterotrophs

can be grouped by DNA GC content or endospores

inclusde several important human pathogens

Actinobacteria

Gram positive phyla

mostly aerobic, filamentous

form branching mycelia also form spores like fungi

high GC content

streptomyces

is an example of actinobacteria (gram positive)

aerobic

GC content is 69-73%

common in soul (extracellular enzymes degrade organic compunds

source of common antibiotics (streptomycin, tetracycline, erthromycin)

forms spores but not endospores

streptomyces: gram and phylum

actinobacteria and gram positive

Firmicutes (endospores)

gram positive

make endospores and low GC content genera

examples include Clostridium and Bacillus

Clostridium

is a firmicutes (endospore) and is gram positive

obligate anaerobe

common in soil

ferments sugar to putyric acid acetone and butanol

many common human pathogens

produce exotoxins

cloustridium- microbial respiration

obligate anaerobes rely heavy on fermentation, turning sugar into butyric acid, acetone, and butanol and they dont have an electron transport chain

Clostridium- gram and phylum

firmicutes and gram positive make endospores

Bacillus- gram and phylum

Firmicutes and gram positive make endospores

Bacillus

Firmicutes Endospores!!

aerobes or facultative anaerobes

chemohetertrophs

motile via peritrichous flagella

source of common antibiotics (bacitracin and polymyxin)

very few human pathogens

Human pathogens from Firmicutes (endospore)

Clostridium: C. botulinum (botulism) C. tetani (tetanus) C. perfringens (gastroenteritis)

Bacillus: B. anthracis (anthrax)

Firmicutes No Endospores

The lactic acid bacteria

gram positive

order: lactobaillales

low GC content

non endospore forming

lack Electron transport system

lactic acid fermentation

mostly aerotolerant anaerobes

ex) lactobacillus, streptococcus, staphylococci

Phylum: Firmicutes Order: Lactobacillales

NO ENDOSPORES

mammals like this the most becuase lactose is what mammals make it is a symbiotic relationship

Lactobacillus

Firmicutes no endospores

gram positive

shape: rods

commonly used in industry with yogurt cheese pickled foods and some beers

Streptococcus

Firmicutes no endospores

gram positive

shape: cocci

many produce hemolytic exotoxins (virulence to cause disease)

some but not all produce toxins but is a common human pathogen

pathogens: S. pyogenes S. pneumoniae S. mutans

Human pathogens from firmicutes no endospores

caused by streptococcus:

S. pyogenes (strep throat, rheumatic fever) S. pneumoniae (pneumonia) S. mutans (tooth decay)

caused by Staaphylococci:

S. aureus (mrsa and a lot of antibiotic resistance)

Staphylococci

Firmicutes no endospores

gram positive

shape: cocci

facultative anaerobes (can also do lactic acid fermentation)

resistant to drying and salt tolerant

notall are harmful a lot beneficial ones

a lot of skin associated microbes

ex) S. aureus

Staphylococci: S. aureus

antibiotic-resistant forms: methicillin-resistant S. aureus aka MRSA

• MRSA and antibiotic resistance come from this

normal inhabitant of human skin microbiome and respiratory tract

dermatological conditions (acne boils)

can cause respiratory infections in the immunocomprimised

causative agen of toxin shock syndrome (TSS)

can cause food poisioning

gram positive

Gram Negative diagram

Phylum: Proteobacteria