Culture medium - solid or liquid preparting used to grow, transport and store microorganisms

• to identify the cause of infection from the clinical sample

• to study characteristics or properties of microorganisms

• to prepare biological product

Nutrients in Media

• Water

• Source of C

• Source of N

• Buffer system

• Source of minerals

Liquid Media - water-based solutions that do not solidify at temperatures above freezing “broths , milks, infusions”

• Methylene blue milk

• Fluid thioglycollate

• Nutrient broth

Semisolid media - exhibits clotlike consistency under ordinary room temperature due to presence of solidifying agent agar or gelatin, use to determine the motility of bacteria, used to determine the motility of bacteria and to localize a reaction at a specific site

Solid media - good for isolating and culturing bacteria and fungi provide a firm surface on which cells can form discrete colonies.

• Liquefiable solid media “reversible solid media”

• Nonliquefiable solid media “do not melt”

Chemical content of Media

Synthetic - chemically defined composition, contain pure chemical nutrients and molecular content

Nonsynthetic or complex - contains biologically complex, undefined components used for general growth

General purpose media - designed to grow a broad spectrum of microbes that do have special growth requirements

Enriched Medium - contains complex organic subtances such as blood, serum, hemoglobin or special growth factors

• Growth factors that are provided in species in order to grow, organic combounds such as vitamins

Selective Media - contains one or agents that inhibit the growth of a certain microbe or microbes, suppressing the unwanted background and allowing growth of the desired ones

Differential Media - grow several types of microorganism but are designed to bring out visible differences among these microorganisms

• Dyes are considered to be effective for differential agents because of their pH indicators

Specimen transport Media - used to maintain and preserve specimens that have to be held for a period of time before clinical analysis

Assay Media - used by technologists to test the effectiveness of antimicrobial drugs and drug manufacturers

Enumeration Media - count the number of organisms in milk, water, food, soil and other samples

Laboratory Techniques

Inoculation - introducing bacteria into the medium

Incubation - Exposing the inoculated medium to optimal growth conditions

Isolation - separating individual microbes and achieving isolated colonies that can be readily distinguished from one another

Inspection - observing cultures microscopically for appearance and growth

Information gathering - testing of cultures with procedures that analyze biochemical and enzyme characteristics

Identification - analysis of collected data to help support a final determination of the types of microbes present in the original sample

Two types of cultures

Pure culture / Axenic - container of medium that grows only a single known species of microorganism

Mixed Culture - container that holds two or more differentiated species of microorganisms

Streak plate method - small droplet of culture or sample spread over surface of the medium with an inoculating loop, sample dilutes the more you streak

Pour Plate - sample will be poured into the plate

Serial dilution - series of sequential dilutions used to reduce a dense culture of cells to a more usable concentration

Spread plate -