Gram Positive Bacteria

• Grouped based on C + G ratio (nitrogen bases cytosine and guanine)

• Divided into 2 Phyla– Firmicutes (low C + G ) – Actinobacteria (High C + G)

• Low G + C ratio • Includes endospore forming and wall-less bacteria

Firmicutes

• Phylum: Firmicute

• 3 Classes:– Clostridia – Bacilli– Mollicutes (mycoplasmas)

Clostridia• Clostridiales

• Clostridium– Obligate anaerobes– Endospores

• C. tenani – tetanus• C. botulinum - botulism

• Epulopiscium– Very large bacteria– Huge genome– Endosymbiont in

surgeonfish– Reproduces by releasing

cells through slit

• Thiomargarita– gamma Proteobacteria – Anaerobic chemolithotroph

that oxidizes sulfur and reduces nitrates

– Even larger than Epulopiscium

– Large vacuole to increase surface area to volume ratio

Single Thiomargarita cell

Fruit Fly

• Bacillales – Includes both rods and cocci – Includes medically/ commercially

important genera

• Bacillus– Endospore-producing rods– Aerobe or facultative anaerobe– B. anthracis- anthrax – B. thuringiensis – insecticide– B. cereus - food borne illness

Bacilli

• Staphylococcus - grapelike clusters of cocci

– facultative anaerobes – Yellow pigmented colonies– common inhabitant of skin and the nasal cavity – grows in foods with high osmotic pressure – S. epidermidis and S. aureus

– S. aureus highly virulent – surgical wound infections– toxic shock syndrome toxin – enterotoxin - induces vomiting– exfolatin toxin – scalded skin syndrome– Folliculitis– Impetigo– MRSA and VRSA

• Lactobacillales

– Commercially important

– Aerotolerant or facultative anaerobes

• Lactobacillus– Aerotolerant; Lactic acid fermenting rod

– common in vagina, intestinal tract, and oral cavity

– used in production of pickles, buttermilk, and yogurt

• Streptococcus– chains of cocci– Aerotolerant; Lactic acid fermenter – Pathogenic strains produce multiple

extra-cellular enzymes and toxins– Responsible for more illnesses and a

greater variety of diseases than any other group of bacteria

• Beta-hemolytic streptococci – S. pyogenes

• Impetigo, strep throat, scarlet fever, necrotizing fascitis

• Alpha-hemolytic streptococci– S. pneumoniae

• Pneumonia, ear infections, sinusitis, meningitis

– S. mutans • Dental carries

• Listeria

– Facultative anaerobe– L. monocytogenes– Contaminates dairy

products– Psychrotroph– Survives inside phagocytes – May be responsible for

stillbirths and birth defects

Mollicutes (mycoplasmas)

• Mycoplasmatales

– Wall-less, highly pleomorphic

– Very small (0.1 - 0.24 µm)

– May produce filaments

– Degenerative evolution

• Mycoplasma – M. pneumoniae– walking pneumonia

• Spiroplasma– Corkscrew morphology– plant pathogen and parasite

of plant feeding insects

• High G + C

Actinobacteria

• Mycobacterium – acid fast; aerobic rods;

filamentous growth– non-endospore former;

mycolic acid – M. tuberculosis – tuberculosis– M. leprae - leprosy

• Corynebacterium– Club shaped, metachromatic

granules– C. diphtheriae –diphtheria

• Propionibacterium • propionic acid fermenter

– Important in swiss cheese production

– P. acnes commonly found on human skin; primary cause of bacterial acne

• Gardnerella• gram variable; highly plemorphic

– G. vaginalis – bacterial vaginitis

• Actinomycetes– Common soil inhabitants– Branching filaments – Asexual spores – Frankia, Streptomyces, Actinomyces

• Streptomyces– most antibiotics are produced by Streptomyces

species– about 500 known species– asexual spores (conidospores)– Produce gaseous geosmin

• Actinomyces – facultative anaerobes

– mouth and throat of animals – A. israelii - actinomycosis (tissue-destroying

disease affecting the head, neck, or lungs)

• Frankia – nitrogen fixing bacteria– Forms root nodules with alder trees

• Highly diverse morphology and physiology• Frequently inhabit extreme environments• Three primary groups are halophiles, thermophiles

and methanogens

Domain Archaea

• Currently classified into 3 Phyla– Crenarchaeota– Euryarchaeota– Korarchaeota

Euryarchaeota• Gram+ to gram variable halophiles, methanogens

and a few thermophiles – Halobacteriales

• Obligate halophiles– Bacteriorhodopsin based light capturing system

• Methanobacteriales– Methanogens

• Convert CO2, H2 and organic acids into methane

– Largest known group of archaea

– Gram +; Obligate anaerobes

Crenarchaeota– Gram-; most thermophiles– Sulfolobales

• acidophilic thermophilic sulfur metabolizers

– Desulfurococcales• Hyperthermophiles

• Korarchaeota– No members have ever been observed– Known only from environmental rRNA

samples