CAVEAT!!!Usually we do these procedures

with a pure culture◦Grow bacteria in broth◦Streak on plate◦Grow single colony on broth

Microbial DNA ExtractionBridges 2014

Cheek Cell

Bacterial Cell

Step One: LysisBreaking apart the cellPhysical

◦Vortex◦MicroBeads

Chemical◦MD1

SDS Disrupts membrane and denatures

proteins

Step Two: Separation from DebrisCentrifugationPrecipitation of Proteins More Centrifuging

Supernatant

Pellet

Step Three: Clean DNABind to spin filter

◦Salt solution◦Silica filter

Wash with ethanol◦Inhibits PCR

Elute off of filter

ContaminationIt is important when working with

bacteria to use sterile technique◦Wipe work area, pipets, and pipet boxes with

EtOH◦Use aerosol filter pipets◦Keep tips covered◦Change tips

Especially if potentially contaminated

◦Change gloves often!◦Keep tubes closed as much as possible◦Do NOT touch inside of tubes

STAY ORGANIZED!