Lecture #10: Nutrition, Media & The Enterics Flashcards
Nutrition
Powers cell.
Provides macronutrients and micronutrients cells need for biosynthesis, energy conversion (food to ATP).
Specific metabolic needs of specialists.
Macroelements
Needed in relatively large amounts.
C, H, O, and to a lesser amount N, P, S.
Why? C, H, O for all 4 classes of the ‘Molecules of Life;’ Carbohydrates,
Fats,
Proteins,
Nucleic Acids.
N, P, S—especially for Proteins, NA’s.
Macroelement Cations
Potassium, Calcium, Magnesium, and iron exist as cations and play a variety of roles.
activate enzymes, work with carrier proteins and cofactors, set up charge differentials, stabilize molecules and ribosomes and membranes, shuttle across membranes to assist uptake.
In essence, to drive metabolism.
Microelements
Nutrients required in small amounts by microorganisms. Also called trace elements.
The micronutrients-manganese, zinc, cobalt, molybdenum, nickel, and copper-are needed by most cells.
Micronutrients are a part of certain enzymes and cofactors, and they aid in the catalysis of reactions and maintenance of protein structure.
Required in tiny amounts for specialized structures or compounds, many are metals and are the central molecule in molecules designed for energy transfer.
Specific Needs for Specific Physiologies
Some microorganisms have particular requirements that reflect their specific morphology or metabolic capabilities. But no matter what their nutritional requirements, microbes require a balanced mix of nutrients. If an essential nutrient is in short supply, microbial growth will be limited regardless of the concentrations of other nutrients.
Specific structural needs for forms that live in high heat, high salt, low temperature, soils with high metal concentrations, or forms that have variant metabolisms.
Trace elements needed vary!
Growth Factors
Organic compounds needed for growth that cells can not make. Can’t grow unless they get it from outside source. Vitamins, amino acids, nitrogen rings for nucleotides.
Heterotroph
An organism that uses reduced, preformed organic molecules as its principal carbon source.
Uses reduced compounds (i.e., sugars) for C source, as well as for electrons to make energy (ATP).
Autotroph
An organism that uses CO2 as its sole or principal source of carbon.
Uses CO2 for C source and inorganic molecules for electrons to make energy (ATP).
Symbionts & Parasites
For symbionts and parasites, dependence on host or partner such that genes have been lost. Streptococcus pyogenes and 3 key amino acids. Growth factors.
Limiting Nutrients
Just as in Chemistry, limiting reactant limited the amount of product; limiting nutrient will set the limits on growth even if the others are abundant.
General Nutrition Need
All organisms require carbon, hydrogen, oxygen, and a source of electrons.
Carbon is needed to synthesize the organic molecules from which organisms are built. Hydrogen and oxygen are also important elements found in many organic molecules.
Electrons needed for two reasons. The movement of electrons through ETCs and during other oxidation-reduction reactions can provide energy for use in cellular work. Electrons are also needed to reduce molecules during biosynthesis.
- Why? Electrons power cells—they are used to generate ATP, the energy currency for the cell.
- The most common source is H. In biological systems, reduced is equivalent to having stored energy = having H.
Reduced & Oxidized
Reduced – Has Energy to Give.
Oxidized – Energy Poor.
For living organisms, reduced means having hydrogen.
Are Bacteria Strict in their Diet?
Not typically. Most bacteria are versatile, and can utilize a number of different substances for food.
Can find bacteria to degrade most anything; rubber, flesh, crude oil, styrofoam, soap scum…
One man’s junk is another man’s treasure; waste from one bacterium may be the ‘want’ for another and this seems to structure many natural communities.
Phototrophs
Use light as their energy source.
Chemotrophs
Obtain energy from the oxidation of chemical compounds (organic or inorganic).
Lithotrophs
Use reduced inorganic substances as their electron source.
Organotrophs
Extract electrons from reduced organic compounds.
Nutritional Types
You are used to autotroph or heterotroph. That qualifier goes at the end. Refers to carbon source.
Determine energy source (Photo or Chemo) for first qualifier.
The electron source goes between. Lithotrophs get e-from inorganic sources (water, carbon dioxide, hydrogen sulfide, etc.), organotrophs from organic compounds.
Photo-Litho-Autotroph
Photo-Organo-Heterotroph
- the non-Sulfur bacteria, purple and green bacteria. Specialized.
Chemo-Litho-Autotroph
- the forms that extract their energy from things like iron, nitrogen, or sulfur compounds. Ecologically specialized.
Chemo-Litho-Hererotroph
- rare. Use reduced inorganics for energy and electrons, and organics for C. Cycling of nutrients (nitrogen, sulfur).
Chemo-Organo-Heterotroph
Photolithoautotrophs
Use light energy and have CO2 as their carbon source.
Photosynthetic protists and cyanobacteria employ water as the electron donor and release oxygen.
Other photolithoautotrophs, such as the purple sulfur bacteria and the green sulfur bacteria, cannot oxidize water but extract electrons from inorganic donors such as hydrogen, hydrogen sulfide, and elemental sulfur.
Photoautotrophs are important primary producers in ecosystems. That is, they convert light energy into chemical energy that can sustain the chemoorganoheterotrophs that share their habitats.
Chemoorganoheterotrophs
Use organic compounds as sources of energy. Frequently the same organic nutrient will satisfy all these requirements.
Chemoorganotrophs contribute to biogeochemical cycles such as the carbon cycle and nitrogen cycle, in which elements are converted into different forms.
In addition, they’re of considerable practical importance. Many are used to make foods, medical products, and beverages.
Nearly all pathogenic microbes are these.
Prokaryotes Grow on Media
Recipes typically include beef extract or another protein source. Nutrient Agar has beef extract and Tryptic Soy Agar has soy protein (‘vegetarian version’). Could be a sugar instead, or a sugar in addition—the logical sugar is glucose. All the necessary macroelements, and microelements.
Liquid form is a broth. Solid gels due to the presence of agar.
Agar
Most commonly used solidifying agent. Well suited as a solidifying agent.
Melts at about 90 degrees Celsius but, once melted, does not harden until it reaches about 45 degrees Celsius. Thus after being melted in boiling water, it can be cooled to a temperature that is tolerated by human hands as well as microbes.
Furthermore, microbes growing on agar medium can be incubated at a wide range of temperatures.
Finally, agar is an excellent hardening agent because most microbes cannot degrade it.
Agar Dissolves in Boiling Water, Becomes Solid at Room Temperature, and is Inert. At least more so than gelatin. Use the presence of gelatinase as an identifier for soil microbes. A few things do digest agar. A very few.
Defined Medium
Medium in which all chemical components are known.
Complex Media
Media that contain some ingredients of unknown chemical composition. Useful due to fact they may be sufficiently rich to meet all the nutritional requirements of many different microbes. Also often needed if nutritional requirements of microbe are unknown.
The Common Media We Use Are Complex
Natural source media.
–Nutrient Agar contains extract of beef, a digest.
–Tryptic Soy Agar contains soy isolates, largely proteins.
–Blood Agar contains sheep blood which is red blood cells (already complex) along with any associated material.
