Bacterial Identification and Techniques

These flashcards cover key concepts related to bacterial identification techniques, antibiotic sensitivity testing, transformation, and biochemical assays.

What is the zone of inhibition in an antibiotic sensitivity test?

It is the diameter in millimeters of the area around an antibiotic disk where bacteria do not grow, indicating the effectiveness of the antibiotic.

What does a zone of inhibition indicate if there is no growth around the antibiotic disk?

It indicates that the bacteria are resistant (R) to that particular antibiotic.

Define Minimum Inhibitory Concentration (MIC).

MIC is the lowest concentration of an antimicrobial that prevents the visible growth of bacteria.

What is Minimum Bactericidal Concentration (MBC)?

MBC is the lowest concentration of an antibacterial agent required to kill a bacterium over a specific time.

What is the role of CaCl2 in bacterial transformation?

CaCl2 neutralizes the negative charges between the cell and the plasmid, facilitating DNA entry into the cell.

How do competent cells acquire new DNA?

Competent cells can take up free DNA from their environment and incorporate it into their genome through transformation.

What is the purpose of the Sulfide-Indole-Motility (SIM) medium?

SIM medium is used to differentiate bacteria based on sulfur reduction, indole production, and motility.

What is the pH indicator used in Simmon's Citrate Agar (SCA)?

Bromthymol blue, which changes from green at pH 6.9 to blue at pH 7.6 and above.

What does a yellow color in Triple Sugar Iron (TSI) agar indicate?

A yellow color indicates that sugar fermentation has occurred, resulting in an acidic pH.

What type of infections can Enterobacteriaceae cause?

They can cause diarrhea, sepsis, pneumonia, urinary tract infections, and other serious conditions.

What distinguishes Chromagar from other differential media?

Chromagar allows for rapid identification of bacterial species based on the color of the colonies.

What does a pink colony on Chromagar indicate?

It indicates the presence of bacteria expressing the B-galactosidase enzyme.

What is the significance of endospore producing bacteria in UV light exposure?

Endospore producing bacteria require longer UV exposure times before showing a decrease in growth due to their protective nature.

In the context of bacterial conjugation, what is a sex pilus?

A sex pilus is a structure used by bacteria to transfer genetic material from one cell to another during conjugation.

What are the applications of bacterial transformation?

Applications include DNA cloning, protein production, genetic engineering, and genetic exchange.

What is transformation?

Horizontal gene transfer where cells pick up DNA from their environment and incorporate into their genome

Describe how transformation occurs

DNA will bind to protein on cell surface, one strand is digested and the other is taken inside.