Certificate IV in Food Technology
General Microbiology
Lecture 8
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A living microbes are made up C, N, P, O, S, H, K, Fe, Mg, and Ca. These elememets must be obtained in quite large qualities In addition, microbes require some in smaller amounts (micronutrients) e.g. Mn, Zn, Co, Mo etc..
Modes of microbial nutrition.
Microbes can be classified based on how they obtain their carbon and energy.
Heterotrophs
Gain there Carbon from organic the compounds they utilise
Chemoheterotrophsuse organic compounds for energy and carbon just like us.
Photoheterotrophsorganisms that can use light for energy ("photo") and organic compounds ("hetero") for carbon
Autotrophs
Can obtain Carbon from non-organic sourses (ie fix carbon dioxide and turn it into organic molecules) Sometimes called self feeders.
Photoautotrophsget energy from light energy like plants, (eg. cyanobacteria and many other bacteria).
Chemoautotrophsuse chemical energy and fix CO2 (e.g. sulfur oxidizing and nitrifiers) "Chemolithoautotrophs" is a term sometimes used for chemoautotrophs that use inorganic compounds for energy,
Fastidious Organisms
Require a range of vitamins preformed peptides, nuceotides and other specific growth factors
Mildly fastidious organisms can be grown on Nutirent Agar or Broth
More fastidious organisms require more complex mixture and need Enriched media. Such as Blood Agar . milk or liver borth.
Very fastidious organisms may need living cell to grow on.
Bacteria, Fungi feed by absorbing chemicals from their environment. Everything that gets into the cell must enter via diffusion (e.g. O2, H2O, CO2) or via some sort of transport protein or channel. In contrast, most protozoa can phagocytize chunks of material (including whole bacterial cells) and digest them in vacuoles that act like little stomachs.
Diffusion- small or uncharged molecules can diffuse across the plasma membrane.
Facilitated diffusion is just diffusion that utilizes a specific trans-membrane protein (a permease)
Active Transport –utilises tranporter and use ATP to take up nutients against thr diffusuion gradiet
Extracellular enzymes
The enzymes released by various bacteria can be used to identify the bacteria and will determine the type of food it can use
Bacillusproduce extracellular amylase
Cytophagaproduces extracellular cellulases
Pseudomusproduces many enzyme and can make a lot of chaing to food ( food spoilage)
Siderophores
Compounds are used to capture metal irons
Emulsifying agents
"biosurfactants" are extracellular compounds produced by microbes that eat oils.
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