Chapter 11 - The Prokaryotes: Bacteria and Archaea

MICR130 MIDTERM 2

Gram Negative Bacteria Major phyla

• Proteobacteria 

• Cyanobacteria

• Chlamydia

• Bacteroidota

• Fusobacteria

• Spriochaetes

Gram Positive Bacteria Major Phyla

• Low G+C

• High G+C

Proteobacteria

name from Greek-God Proteus

Largest taxonomic group of bacteria 

chemoheterotrophic 

5 classes

The Five Classes of Proteobacteria

Alphaproteobacteria

Betaproteobacteria 

Gammaproteobacteria

Deltaproteobacteria

Epsilonproteobacteria

Alphaproteobacteria

can grow in low levels of nutrients

include agricultrually important bacteria

Some are plant and human pathogens

Select Alphaproteobacteria

• Pelagibacter

• Azospirillum

• Wolbachia

• Rickettsia

• Bartonella

Pelagibacter

One of the most abundant and important organisms on Earth 

Diverse and most common type of marine bacteria 

Important role in oceanic carbon and nutrient cycles

• can converst up to 40% of marine photosynthetic products back to CO2

Wolbachia

Most common infectious bacterial genus in the world

infects many species of insects

• manipulate insect reproduction to increase their own spread

• Interfere with viruses and other pathogens within the host providing a survival advantage to insects that are infected

Human disease relevance

Wolbachia & Humans

Human disease relevance 

• can use to reduce the transmission of mosquito brone disease

  • population suppression

  • population replacement

  • virus blocking

Alphaproteobacteria that cause human disease

Rickettsia

Bartonella

Rickettsia

Human pathogen

trasnmitted by insect and tick bites

causes “spotted fevers”

• R. Rickettsii: causes Rocky Mountain spotted fever (spread via ticks)

Bartonella

Human pathogen 

B, henselae; causes cat-scratch disease 

• cat licks an open wound/bites/scratches human hard enough to break the skin and transmits bacteria

Select Betaproteobacteria

Burkholderia

Bordetella

Neisseria

Bordetella

B. pertussis: causes whooping cough

• common childhood illness

• highly contagious upper respiratory tract infection

• prevented by Tdap and DTap vaccines

  • Tetanus, diphtheria, pertussis

Select Gammaproteobacteria

Pseudomonaidales

Legionellales

Vibronales

Enterobacteriales

Haemophilus

Vibronales

Found in Aquatic habitats

• V.cholerae causes cholera (profuse watery diarrhea) 

  • acquired from contaminated water

• V. parahemolyticus causes gastroenteritis

  • most trasmitted by raw/undercooked shellfish

John Snow & Cholera Epidemic

Demonstrated a linke between cholera and contamintaed drinking pumps

findings and methods have shaped modern epidemiology

Enterobacteriales

Commonly called enterics — inhabit the intestinal tract

faculative anaerobic rods

have fimbria

causes UTIs, upper respiratory tract infection, soft tissue infection, endocarditis, among many other pathologeis

Includes: Escherichia, Salmonella, shigella, klebsiella, serratia, yersinia

Escherichia

E coli: causes foodborne disease and UTI

Salmonella

almost all members of this genus are pathogenic 

common inhabitants of poultry and cattle

Salmonella enterica typically cuases thyphoid fever 

less severe gastrointestinal diseases cuased by other serovar causes salmonellosis

Epsilonproteobacteria

helical or curved

microaerophilic

Select Epsilonproteobacteria

Campylobacter

Helicobacter

Camylobacter

one polar flagellum

C. jejuni carried by animals can spread to edible parts when slaughtered

causes foodborne intestinal diseases

most common bacterial cause of diarrheal illness in the United States

Helicobacter

Multiple flagella

H.pylori: most common cause of peptic ulcers and a cause of stomach cancer

Cyanobacteria

Blue gree “algae”

smallest known photosynthesizing organisms

played an important role in the development on life on earth

• first known organism to produce oxygen

Chlamydia

Very unique developmental cycel

Elementary body is the infective stage

Chlamydia trachomatis 

• most common STI in the US

• in woman if left untreated can lead to pelic inflammatory disease and infertility

• causes trachoma (one of the most common causes of blindness worldwide)

Spirochetes

Coiled (spiral) morphology

Distinctive due to their movement via axial filaments

Trepoma: causes syphilis

Borrelia: cuases lyme diseae

Leptospira: excreted in animal urine. leptospirosis

High G+C ratios examples

Actinomycetota

• Streptomyces

• mycobacterium

Low G+C ratio examples

Clostridiales

• clostridium

• clostridioides

Bacillales

• bacillus

• staphylococcus

Lactobacillales

• streptococcus

• enterococcus

• listeria

Clostridiales

Clostridium

• endospore-producing, obligate anaerobes

• includes disease causing, C. tetanus, C.botulinum, C. perfringens

Clostridioides

• C.difficile: cuases profuse diarrhea

Bacillales

Bacillus

• endospore producing rods

• b anthraces, B. cereus

Mycobacterium

Cell wall has outer lipid layer of mycolic acids that is waxy and water-resistant 

• acid fast

• drug resistant 

• often slow-growing

• pathogenic

M.tuberculosis causes tuberculosis

M. leprae causes leprosy

Streptomyces

produces most of our commercially available antibiotics