Serial Dilution and Standard Plate Count

Flashcards related to serial dilution, plate counts, and related lab techniques.

Serial Dilution

Technique to obtain a viable cell/standard plate count. Reduces cell density to achieve countable plates.

Standard Plate Count

Means of determining microbial density in a culture using the number of colonies a portion of that broth produces when transferred to an agar plate.

Confluent Growth

Bacterial growth completely covers the plate, and you cannot differentiate individual colonies.

Countable Plate

Contains between 30 and 300 colonies.

CFU (colony forming unit)

Each colony arose from one single cell that sat on the agar and went through multiple rounds of division, so each colony is counted as a CFU

Sterile Diluent

A sterile solution used to make dilutions.

Dilution Factor

A means of keeping track of the amount of the original broth in each tube Fraction (1/10), as a ratio (1:10), or as an exponent (10- 1).

Dilution Factor Calculation

The number of milliliters (mL) being transferred divided by the total number of mL in the solution (amount transferred + diluent).

Confluent Plates

Have no discernible colonies, but instead have large areas or patches of growth.

Spread Plate Technique

Uses an alcohol lamp and alcohol to sterilize a glass spreader (bent glass rod), which is used to spread the liquid all over the surface of the agar.