W2 asynchronous Anaerobic spore forming gram positive rods · Kingdom: Bacteria · Family: Clostridiaceae · Genus: clostridium · Main characteristics: o Gram-positive rods; motile with peritrichous flagella ;1um x 20 um o Ubiquitous saprophytes/ mammalian intestine o Low G/C content o Produce endospore (spore-forming bacteria) o Strictly anaerobic metabolism (anaerobic respiration and fermentation; reduce sulphate to sulphite to obtain energy) Clostridia are obligate anaerobes · Produce ATP through 2 routes o Anaerobic respiration and fermentation Anaerobic respiration: electron acceptor is exogenous; ETC; no oxygen NAD+ NADH + H+ Plasma Membrane Terminal exogenous electron acceptor Aerobic Respiration O Organic Energy and Electron Source e* Electron Transport Chain (ETC) e Anaerobic Respiration SO,2 PMF generated to produce ATP L Chemical, Transport, Mechanical work Bacterial growth and function o in the case of clostridium, the final electron acceptor is sulphate which is then reduced to sulphate o Oxygen is highly oxidising so there is a lot more ATP production from aerobic respiration o Sulphate is less oxidising so there is less ATP production with anaerobic respiration " This is why anaerobic bacteria tend to grow and divide much slower Fermentation (electron acceptor is an endogenous organic molecule; no ETC; no oxygen) ADP ATP Eg. lactate, ethanol, propionic acid, acetic acid etc Organic Energy and Electron Source SLP NAD+ > NADH + H+ e Fermentation Products 1 Clostridia utilise the butyric fermentation pathway and produce butyric acid from pyruvate Endogenous electron acceptor eg. pyruvate . Pyruvate will act as the electron acceptor · This is enough energy to undergo substrate level phosphorylation where ADP -> ATP Clostridia produce endospores · Dormant, dehydrated, highly resistant 'survival' structures carrying bacterial DNA · Produce unfavourable conditions - to survive o i.e if exposed to oxygen, will produce a bacterial spore . spores can be placed in fi different positions depending on the species of clostridium o terminal o subterminal o central distinct components: o exosporum helps attach to surfaces o spore coat (protein) " huge chunk of protein o cortex (peptidoglycan) o core (low h2O; small acid soluble spore protein- SASP; DPA-Ca2+ · makes it highly resistant " SASPs saturate and protect the DNA from wet and dry heat · DPA complexed with calcium in the core and mops up excess water
W2 asynchronous Clostridium sp: germination of spores Stage 1: . Exposure to specific germinant and activation (irreversible) o Spore is exposed to a germinant. Binds to spore and initiates germination Stage 2: 1) partial rehydration 2) DPA- Ca2+ release fi) loss of some resistance Stage 3: 1) Cortex hydrolysis 2) Full core rehydration and expansion fi) Loss of resistance and dormancy Stage 4) (outgrowth) 1) SASP degradation 2) Metabolism fi) Escape from spore coat and division Organism and Spore Structure Historical Derivation Spore Structure Disease Frequency of Disease Clostridium botulinum botulus: sausage Oval, subterminal Botulism (foodborne, infant, wound) Uncommon Clostridium difficile: difficult difficile Oval, subterminal AAD; PMC (HAI) Very common Clostridium perfringens perfringens: 'breaking through' Large rectangular Gl infection Common Clostridium tetani tetani: tension Round,