Firmicutes: Low G+C Gram-Positive Bacteria Flashcards
Peptidoglycan Structure differences
number of interpeptide bridges between glycan chains
Endospore Production
- heat-resistant
- germinates in optimal growth conditions
- location and size used to identify bacteria
Class Clostridia
- anaerobic
- endospore
- food spoilage
Clostridium Stickland Process
- survive heat treatment of canned food
- fermentation, ATP produced
- forms: ammonium, H2S, fatty acids, amines
Clostridium botulinum
botulism
respiratory muscle paralysis
Clostridium tetani
- lockjaw
- affects nervous system
- painful muscle contractions
Clostridium perfringens
- gas-gangrene and food poisoning
- toxins that cause necrosis
Clostridium acetobutylicum
- butanol production
- useful
2 Orders of Class Bacilli
- Bacillales
- Lactobacillales
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Genus Bacillus
- endospore
- chemoheterotrophic rods
- peritrichous flagella if motile
- aerobe / facultative aerobe
- catalase +
antibiotics
Impact of Genus Bacillus
- bacitracin
- gramicidin
- polymyxin
Bacillus anthracis
- anthrax
- skin ulcers
- in soil
Bacillus cereus
- food poisoning
- β-haemolysis
2 Useful Bacillus species
- Bacillus thuringiensis
- Bacillus sphaericus
- parasporal body in sporangium
- toxic to some insects
Which Family does not superficially fit into the Order Bacillalles?
Family Staphylococcus
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Genus Staphylococcus
- facultative anaerobe
- non-motile
- cocci
- irregular clumps of cells
- oxidase -
- catalase +
Staphylococcus epidermidis
wound infections
Staphylococcus aureus
- abscesses, pneumonia
- food poisoning
- nose mucous membrane, skin and digestive system of warm-blooded animals
2 Resistant S.aureus strains
- Meticillin RSA
- Vancomycin RSA
- Both are resistant to multiple drugs
How is S.aureus distinguished from S.epidermidis?
presence of coagulase:
- causes blood plasma to gel
- β-haemolysis
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Order Lactobacillales
- grow together with yeast
- non-sporulating
- non-motile
- fermentation
- no cytochromes
- energy from sub-level phos
- facultative anaerobes
Genus Lactobacillus
- rods
- no catalase
- not usually pathogenic
Lactobacillus
Homolactic fermentation
EM pathway (lactic acid and energy)
Lactobacillus
Heterolactic fermentation
phosphoketolase pathway (lactate and ethanol produced)
Lactobacillus
- fermented foods and drinks
- sometimes food spoilage
Lactobacillus bulgaricus and Streptococcus thermophilus
flavour and aroma of yoghurt
Genus Leuconostoc
- facultative anaerobe
- cocci
- pairs or in chains
- no catalase or cytochromes
- plants, silage and milk
- heterolactic ferm: glucose to D-lactate and ethanol or acetic acid
Impact of Genus Leuconostoca
- fermented foods and drinks
- osmotolerant
- food spoilage of high sugar foods
Leuconostoc mesenteroides
produce dextran from sucrose
Enterococcus, Streptococcus and Lactococcus
- closely related genera
- chemoheterotrophic
- mesophilic
- non-sporulating
Identification for Ent, Strep, Lacto
- ability to lyse red blood cells
- serological studies: different cell wall antigens on different strains
α-Haemolysis (Ent, Strep, Lacto)
- Streptococcus pneumoniae
- greenish zone
- incomplete haemolysis
β-Haemolysis (Ent, Strep, Lacto)
- Streptococcus pyogenes
- clear zone
- complete haemolysis
Streptococcus pyogenes
sore throat
rheumatic fever
Streptococcus mutans
tooth decay
Streptococcus pneumoniae
pneumonia
Lactococcus lactis
- useful
- production of cheese
