MICB 3303 Bacterial Phylums

Deinococcus-Thermus

• Deinococcus radiodurans

  • Not thermophilic

  • Extremely resistant to radiation and desiccation

  • Rapid DNA repair

• Thermus aquaticus

  • Source of Taq polymerase for PCR

  • Thermophile (70-75 C)

Cyanobacteria

• Oxygenic photosynthesis

• 2 phototsystems (PSI and PSII)

• ATP and NADPH

• Genus - Spirulina

  • Found in fresh and salt water

  • High carotene (Flamingoes)

  • Can be used as dietary supplement

• Genus - Anabaena

  • Aquatic

  • 2 processes:

    • Oxygenic photosynthesis

    • N₂ fixation

What is the problem with Anabaena having oxygenic photosysthesis and N₂ fixation?

Problem: The enzyme nitrogenase for N₂ is sensitive to oxygen

Solution: Differentiate vegetative cells into heterocysts devoid of oxygen to fix N₂

Chlamydiae

• Genus - chlamydia

  • Gram -, obligate intracellular bacteria

  • C. pneumonia

  • C. trachomatis

    • Major cause of STI

Spirochete

• Flexible, helical shape

• Flagella (in periplasm)

• Treponema pallidum

  • Syphillus

• Borrelia burgdorferi

  • Lyme disease

Bacteroides

• Genus - bacteroides

• Obligate anaerobe

• Degrade complex, dietary polysaccharides

• Important in human intestinal tract

Proteobacteria

5 major groups:

• Alpha

• Beta

• Gamma

• Delta

• Epsilon

Diverse cell groups and metabolism:

• Heterotrophs (HT)

• Phototrophs (PT)

• Lithotrophs (LT)

Alpha Proteobacteria

• Some are PT

• Anoxygenic photosynthesis

  • Water cannot be used as electron donor

• Members:

  • Rhizobium - root nodules, fixes N₂

  • Agrobacterium - plant pathogen

    • T-DNA transfer into plant cell which causes galls

  • Rickettsia - Human pathogen

    • Obligate, intracellular parasite

    • Rocky Mountain Spotted Fever

• Genus - Caulobacter

  • Gram -, aquatic

  • Dimorphic

  • Cell division generates:

    • Motile swarmer cell

    • Non-motile stalked cell

      • Tip of stalk is called holdfast

Why are Caulobacter stalked?

1. Attachment via holdfast

2. Increase SA for nutrient uptake

Beta Proteobacteria

• Some are chemolithotrophs

  • Inorganic compounds as electron source

• Oxidizes ammonia to nitrite

• 1st step of nitrification

• Human pathogens:

  • Neisseria meningitides

    • common cause of bacterial meningitis

  • Burkholderia cepacia

    • Human respiratory pathogen, is also a plant pathogen

Gamma Proteobacteria

• Enteric - intestine

  • Facultative anaerobes

  • Escherichia coli

    • Pathogenic (O157: H7)

  • Salmonella

    • Food poisoning

• Non-enterics

  • Pseudomonas aeruginosa

    • Pathogen in cystic fibrosis and burn wounds, will glow

    • Pigment pyoverdines - siderophore

  • Vibrio cholera

    • Cholera

  • Shewanella

    • Non-pathogen, aquatic and soil, extracellular electron transport

    • Can make mudwatts

Delta Proteobacteria

• Genus - Myxococcus

  • Gram -, social soil bacteria

  • Attack other bacteria

  • Gliding moltility (no flagella)

  • Nutrient limiting, cells assembles into fruiting bodies

    • Dormant myxospores at top

Epsilon Proteobacteria

• New recent phylum - Campylobacterota

• Microaerophilic

• Motile

• Helical or vibroid

• Gram -

• Two major genra that cause diseases

  • Campylobacter

    • C. fetus which causes reproductive disease and abortions in cattle and sheep

    • In humans, causes:

      • Septicemia - pathogens or toxins in blood

      • Enteritis - inflammation of intestinal tract

      • Guillain-Barre syndrome (GBS) - flaccid paralysis, causes immune system to mistakenly attack the host’s nervous system even after infection is cleared. This is called molecular mimicry becasue the Campylobacter spp lipooligosaccharides resembles components found on nerve cells

      • C. jejuni - found in intestinal tract of animals, transmitted to humans via contaminated food and water, contact with infected animal or anal-oral sexual activity

  • Helicobacter

    • Gastritis

    • peptic ulcer

    • gastric cancer

    • H.pylori

      • obligate microaerophile

      • Can only use glucose as a carb, metabolizes both respiratory and fermentative pathways

      • Uses pentose phosphate pathway to provide NADPH for biosynthesis

      • Entner-Doudoroff pathway for pyruvate

Firmicutes (Low G and C, Gram +)

• Pathogens:

  • Staphylococcus (MRSA)

  • Streptococcus

• Also has good bacteria:

  • Lactobacillus

  • Lactococcus

  • Lactic acid fermentation

    • Cheese and yougurt

• Spore formers:

• Two major genra:

  • Clostridium

  • Bacillus

  • C. tetani

  • C. botulinum

    • Botulism, produces neurotoxin

  • C.difficile

    • Colitis, inflammation of colon

  • B. subtilis

    • Non pathogenic soil bacterium

  • B. anthracis

    • Antrax

Acintobacterium

• Genus - Myobacterium

• Human pathogen

• M.tuberculosis

  • tuberculosis

• M.leprae

  • leprosy

• Acid-fast cell walls with waxy lipids

• Genus - streptomyces

  • Form hyphae and mycelia

  • Source of many antibiotics

  • Makes chemical geosmin

    • odor of moist soil