My internship in laboratory at 2025.11.7

Morning: Learned Streak Plate Technique

Transferred a microbial colony from one culture dish to another to dilute the population and obtain isolated pure colonies for DNA sequencing.

Procedure:

1. Sterilized tools.
2. Inside a UV cabinet, used a sterilized inoculation loop to scrape a small amount of the microbial colony. Streaked tight zigzag lines in the first quadrant (approximately 1/4 of the new, sterile culture dish).
3. Sterilized the inoculation loop by flaming it in an alcohol burner until the wire tip glowed red and the rest passed through the flame. Allowed it to cool until it could briefly touch the edge of the medium without melting it to prevent killing microorganisms.
4. Dragged the loop through the first quadrant streaks and streaked several new lines in the adjacent second quadrant without touching the first area.
5. Re-sterilized and cooled the loop again, then streaked the third quadrant.
6. Repeated sterilization and cooling, then streaked the fourth quadrant (where isolated single colonies are most likely to appear).
7. Inverted the culture dish to prevent condensation from disrupting the colonies.
8. Placed the dish in an incubator and cleaned up the work area.

Note: The culture medium contained nitrogen sources, carbon sources, and sodium chloride (essential environment for microbial growth).

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Afternoon: Observed Bacterial Genomic DNA Extraction Experiment
specific procedures are described below