gram positive

Key Characteristics of Gram-Positive Bacteria

• Thick peptidoglycan layer

• Presence of teichoic acids

• Lack of an outer membrane

• Generally stain purple in Gram stain

• Common shapes: cocci (spherical) and bacilli (rod-shaped

Gram-Positive Bacteria

• Phylum Actinobacteria (high G + C ratios)

• Phylum Firmicutes (low G + C ratios)

Phylum Actinobacteria

• High G+C content

• ALL chemoorganoheterotrophs

• Produce metabolites

• Filamentous, rod

Phylum Actinobacteria - Order Actinomycetales

• Genus Actinomyces

• Oral cavity, dental plaque

• Genus Bifidobacterium

• Sold as probiotics

Actinobacteria - Order Mycobacteriales

• Genera Corynebacterium, Tuberculosis, Leprosy

Actinobacteria - Order Mycobacteriales• Tuberculosis

• M. tuberculosis

• Droplets, aerosol transmission

• Infects resident macrophages in lungs

• cough, fever, weight loss

Actinobacteria - Order Mycobacteriales• Leprosy

• M. leprae

• prolonged skin contact

• Obligate intracellular pathogen

• nerve damage, skin lesion

Actinobacteria - Order Mycobacteriales• Genera Corynebacterium

• C. diptheriae: diptheria

• Airborne transmission

• Toxin-mediated disease

• Symptoms: thick grayish pseudomembrane on pharynx

Actinobacteria - Order Propionibacteriales

• causative agent of acne

• Body odor

Actinobacteria: Order Streptomycetales • Genus Streptomyces:

• Large operons(biosynthetic geneclusters)

• soil bacteria responsible for most of antibiotics

• Self-resistance with antibiotic resistance

Phylum Firmicutes (Bacillota)

• Low G+C Gram-positive bacteria

• Some form endospores

• Cocci or bacilli

• Includes those without cell wall(mycoplasmas)

• Bacillus, Staphylococcus, Clostridium

Phylum Firmicutes - Order Bacillales

B. subtilis

• Non-pathogenic ;model organism

• food poisoning

• Bacillus anthracis

• Anthrax

• zoonotic

• Bioterrorism

Phylum Firmicutes - Order Staphylococcales

• S. aureus

• Toxic shock syndrome

• MRSA

Phylum Firmicutes - Order Lactobacillales

• Lactobacillus (Genus)

• lactic acid fermentation

• in GI, urogenital tract (impt forhomeostasis, normal flora)

• Found in dairy products, meat,water, sewage, beer, fruits

• Production of fermented food: sourdough, Swiss/hard cheeses, yogurt, sausages, probiotic

• Some food spoilage

Phylum Firmicutes - Order Lactobacillales families?

Family Streptococcaceae, Enterococcaceae, Listeriaceae

Phylum Firmicutes - Order Lactobacillales -Family Streptococcaceae

• Genus Streptococcus

• Lyse RBC

• Strep throat (S.pyogenes)

Phylum Firmicutes - Order Lactobacillales -Family Enterococcaceae

• Enterococcus

• Strictly fermentative

• Opportunistic pathogens (UTI,endocarditis)

• HGT of resistance genes

Phylum Firmicutes - Order Lactobacillales - Family Listeriaceae

• Listeria monocytogenes

• Foodborne infections

• At risk avoid eating: soft cheeses, delimeats

Phylum Firmicutes - Order Mycoplasmatales

• *controversy overwhere to place....

• Genus Myocoplasma(don't have a cell wall)

• Cause pneumonia("walking pneumonia")

Phylum Firmicutes - Class Clostridia species?

C. tetani, C. botulinum, C. difficile

Phylum Firmicutes - Class Clostridia • C. tetani

• Endospore in soil, dust,feces (animals/humans)

• Enters by break in skin

• Neurotoxin tetanospasmin

Phylum Firmicutes - Class Clostridia • C. botulinum

• Foodborne, ingestion of botulinum toxin

• Canned food

• Neurotoxin (paralysis)

• Therapeutic uses: Tremors, Migraines/tension headaches, Plastic surgery(wrinkles)

Phylum Firmicutes - Class Clostridia • C. difficile

• Severe GI disease, colitis, toxic megacolon

• Overabundance in gut after antibiotic treatment (alters/creates imbalance in gut microbiota)