BIOS5480 Microbial World - Flashcards

Flashcards covering key vocabulary and concepts related to microbial culturing and growth of microorganisms.

Microbial Growth Requirements

Microorganisms need specific conditions and nutrients to grow, and the type of medium used significantly impacts their growth.

Nutritional Classification

Microorganisms can be classified based on their nutritional needs, specifically their carbon, energy, and electron sources.

Importance of Culturing Microorganisms

Essential for studying microorganism function, phenotype, and ecological importance, cultivation and manipulation are vital. Molecular Phylogeny is based on culture independent amplicon sequencing such as 16S rRNA.

Autotrophs

Organisms that use CO2 as their sole carbon source.

Heterotrophs

Organisms that require organic substances from other organisms as their carbon source.

Phototrophs

Organisms that use light energy.

Chemotrophs

Organisms that use chemical energy sources (organic or inorganic).

Lithotrophs

Organisms that use reduced inorganic substances as electron sources.

Organotrophs

Organisms that use organic compounds as electron sources.

Photoautotrophs

Use light energy and CO2 as the sole source of carbon.

Photoheterotrophs

Use light as an energy source and organic compounds as electron and carbon sources.

Chemoautotrophs

Oxidize inorganic compounds (e.g., NO3, Fe, S) to obtain energy and electrons, using CO2 as a carbon source.

Chemoheterotrophs

Use organic compounds to provide energy, electrons, and carbon.

Carbon

All cells require this element, and it typically makes up about 50% of a cell's composition.

Nitrogen

Typical cell constituent, available in inorganic and organic forms, and is essential for various cell functions.

Phosphorous (P)

Required for nucleic acids and phospholipids.

Sulfur (S)

Found in cysteine and methionine (amino acids), vitamins (thiamine, biotin, lipoic acid), and Coenzyme A.

Potassium (K)

Required for some enzymes, such as Pyruvate Kinase.

Magnesium (Mg)

Stabilizes ribosomes and membranes and is essential for many enzymes (approx. 300, including ATP synthesis or use).

Calcium (Ca)

Stabilizes cell walls.

Siderophores

Iron-chelating compounds produced to capture/chelate low levels of available iron.

Non-Selective (Complex) Media

Use of media that contains many nutrient-rich, non-defined components, permitting the growth of a wide range of microorganisms.

Selective (Defined) Media

Media containing ingredients that inhibit the growth of some organisms but allow others to grow.

Differential Media

Media containing compounds that allow groups of microorganisms to be visually distinguished by the appearance of the colony or surrounding media.

Defined Media

A medium that is non-rich and fully defined with respect to all components and the provision of specific carbon sources.

Culture Media

Culture supply the nutritional needs of microorganisms and can be either chemically defined (defined medium) or undefined (complex medium).

Autoclave

A device that uses pressurized steam at high temperatures (121-132°C) to sterilize media and equipment.

Lag Phase

Cell numbers are low, and cells are adjusting to their environment.

Exponential Growth Phase

Cells have adapted to their environment and are not limited by nutrient availability or environmental constraints.

Stationary Phase

Cells have become limited by nutrient availability, buildup of toxic products, and/or environmental constraints.

Death Phase

Population is no longer able to be sustained, and cells lyse.

Binary Fission

A process where one parent cell splits into two equal daughter cells.

Semi-Logarithmic Graph Paper

A graph paper with an arithmetic scale on one axis and a logarithmic scale on the other axis.

Doubling Time/Generation Time (td)

The time taken for the population to double in size.

Continuous Culture

All cells in a population achieve a steady state, allowing detailed study of bacterial physiology.

Chemostat

Ensures logarithmic growth by constantly adding and removing equal amounts of culture media.

Batch Culture

A closed system that is constantly changing.

Chemostat Culture

An open system with constant volume, where fresh medium addition equals spent medium loss, and volume, cell number, and nutrients are constant.

Batch vs. Chemostat - Nutrient Effects

Batch cultures are affected by nutrient availability for both growth rate and growth yield, while chemostats allow independent control of growth rate and growth yield.

Dilution Rate

The rate at which fresh medium is added and spent medium is removed in a chemostat.