How can you identify bacteria on an agar plate?
Bacteria. Each distinct circular colony should represent an individual bacterial cell or group that has divided repeatedly. Being kept in one place, the resulting cells have accumulated to form a visible patch. Most bacterial colonies appear white, cream, or yellow in color, and fairly circular in shape.
How do you identify different types of bacteria?
Bacteria are identified routinely by morphological and biochemical tests, supplemented as needed by specialized tests such as serotyping and antibiotic inhibition patterns. Newer molecular techniques permit species to be identified by their genetic sequences, sometimes directly from the clinical specimen.
How do you count bacterial colonies on agar plate?
After incubating the plate under appropriate conditions for the microorganism, the colonies are counted. For the spread, pour, or drop methods, the colony counting is self-explanatory: count each colony dot once. A marker can be used pointing each counted colony on the back of the Petri dish.
How can you identify a bacterial colony?
The main difference between bacterial and fungal colonies is that bacterial colonies are small, smooth or rough colonies with defined margins while fungal colonies are large colonies with a fuzzy appearance. Furthermore, bacterial colonies look wet and shiny while fungal colonies are powder-like.
Why are agar plates incubated at 37 degrees?
Different bacteria like to grow at different temperatures. By changing the temperature, he can study the bacteria while they are stressed. Organisms that grow best at human body temperature, which is approximately 37 degrees Celsius (98.6 degrees Fahrenheit), are called mesophiles.
What are the 3 main bacteria shapes?
Individual bacteria can assume one of three basic shapes: spherical (coccus), rodlike (bacillus), or curved (vibrio, spirillum, or spirochete).
How do you count bacteria?
Calculate the number of bacteria (CFU) per milliliter or gram of sample by dividing the number of colonies by the dilution factor multiplied by the amount of specimen added to liquefied agar.