Microbiology 2 - Anaerobic Spore Forming Gram Positive Rods Clostridium Tetani is an example of anaerobic gram-positive spore forming rods - Kingdom: Bacteria - Family: Clostridiaceae - Genus: Clostridium - Main Characteristics: o Large gram-positive rods; motile 1um X 20um · Ubiquitous saprophytes " Spores are everywhere in the soil and in the guts of the mammals o Low G/C content o Produce endospores (spore-forming bacteria) o Strictly anaerobic metabolism (anaerobic respiration and fermentation) Obligate Anaerobes - Generate their ATP through two processes; - Anaerobic respiration o electron acceptor is EXOGENOUS to the bacterial cell o electron transporter chain o no oxygen involved o organic source - glucose · is broken down through glycolysis " protons are pumped out of the cell and generated PMF (proton motive force) · PMF is what activates ATPase to produce ATP o Electron is passed through to the sulphate makes it sulphide o Sulphate is less oxidising so less ATP is produced, less growth Organic Energy and Electron Source NAD+ NADH + H+ Plasma Membrane e e- Electron Transport Chain (ETC) e™ Aerobic Respiration Terminal exogenous electron acceptor O2 Anaerobic Respiration SO42- PMF generated which activates ATPase to produce ATP - Fermentation o Electron acceptor is ENDOGENOUS o No electron transport chain o No oxygen o Organic energy source is broken down by glycolysis o This oxidation generates enough energy to generate substrate level phosphorylation . Where ADP is directly converted to ATP
o First intermediate is pyruvate Pyruvate is then reduced into various fermentation products . E.g. lactate, ethanol, propionic acid, acetic acid Spores - Dormant, dehydrated structures - Highly resistant to antibiotics, antimicrobials, UV, heat etc - Is formed when the bacterial cell is exposed to unfavourable conditions o E.g. oxygen - Located in various parts of the cell; Terminal (oval) · Seen at the poles of cells, O Subterminal (round) · Between these two extremes, usually seen far enough towards the poles but close enough to the centre Central (rectangular) More or less in the middle - 4 main parts: o Exosporium " Flimsy structure . To allow the spores to adhere to surfaces o Spore Coat · Huge layer of protein o Cortex · Chunk of peptidoglycan o Core . Contains all bacterial genetic material · Dehydrated - 10%-30% water · SASP - small acid soluble sore proteins . bind to the spore DNA and protects it from external sources e.g. UV . DPA-Ca2+ . Binds free H20 · Protects against wet heat Spore Formation: vegetative cell free endospore spore coat mother cell developing spore coat ASM Digital Image Collection. Merkel - Spore formatting bacteria divide by binary fission when environmental condition are not adverse - The DNA condensed and aligns itself in the centre of the cell (mother cell) - The DNA divides into two complete copies
o And the mother cells membrane invaginates to envelope the developing fore spore - The mother cell membrane continues to grow and engulfs the developing spore o Is now surrounded by two