Lectrure 10: Bacteria and Diseases

Bacteria and Human Health

• Campylobacter and Helicobacter are examples of "bad" bacteria that can cause diseases such as enteritis, Guillain-Barré syndrome, gastric cancer, gastritis, and peptic ulcer disease.
• Lactobacillus and Lactococcus are examples of "good" bacteria that are involved in lactic acid fermentation, and are found in cheese and yogurt.

Phylum Firmicutes: Spore Formers

• The phylum Firmicutes includes two major genera: Clostridium and Bacillus.
• Clostridium tetani causes tetanus, Clostridium botulinum causes botulism and produces a neurotoxin, and Clostridium difficile causes colitis and inflammation of the colon.
• Bacillus subtilis is a non-pathogenic soil bacterium.
• Bacillus thuringiensis produces an insecticidal toxin and is used in Bt corn.

Shewanella

• Shewanella is a gram-negative bacterium that can transfer electrons extracellularly onto certain metals, a process known as "breathing" metals.
• This process occurs at the anode (low O2) and cathode (high O2) of an electrical system.

Delta Proteobacteria

• The genus Myxococcus includes gram-negative, social, soil bacteria that attack other bacteria to swarm on the surface.
• Myxococcus bacteria have gliding motility and form fruiting bodies with dormant myxospores when nutrients are limited.
• When nutrients become available, myxospores germinate into vegetative cells.

Epsilon Proteobacteria

• Epsilon Proteobacteria are also known as Campylobacterota.
• This phylum includes pathogens such as Campylobacter and Helicobacter.

Phylum Firmicutes (Low G+C Gram+)

• This phylum includes pathogens such as Staphylococcus (MRSA) and Streptococcus.
• Only two genera of bacteria, Bacillus and Anthracis, have the ability to form spores.
• Anthracis causes anthrax.

Bacillus Sporulation

• Bacillus sporulation is a survival mechanism that occurs in response to a lack of nutrients.
• The process involves the formation of a spore inside a mother cell, which will eventually lyse and release the mature spore.
• The spore is dormant, heat and stress resistant, but can germinate and become an actively growing cell when nutrients become available.
• Bacillus senses stress to initiate sporulation through nutrient limitation.

This quiz tests your knowledge on bacteria such as Campylobacter, Helicobacter, Lactobacillus, and Lactococcus, and the diseases they cause including enteritis, Guillain-Barré syndrome, gastric cancer, gastritis, and peptic ulcer disease.