What is the reason for flaming the tubes before and after each transfer?

Flaming the tubes before and after each transfer is a crucial practice in microbiological techniques to prevent contamination. The heat creates a sterile environment by killing any potential microbes on the lip of the tube, ensuring that only the intended microorganisms are transferred. This helps maintain the integrity of the culture and ensures accurate experimental results. Additionally, it serves as a visual signal that the tube has been properly sterilized.