Effect of garlic and mint on bacterial growth

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Independent: Presence garlic/mint

Dependent: Zone inhibition around disc

Control:

Conc. plant material

Lawn bacteria on petri dish

Contamination petri dish by other microbes

Same vol. plant material on each disk

Method:

Make plant extract, crush 3g plant material w/ 10cm3 industrial denatured alcohol.

Shake 10mins.

Pipette 0.1cm3 extract

onto sterile paper discs.

Allow draw on sterile petri dish.

Meanwhile label agar plates with

date & split into 3 sections.

2 for each type of plant extract

& 1 for control with distilled water on disc.

Place 1 disc of each extract in each

quadrant agar plate, close & tape w/ hazard tape.

Leave incubate overnight & observe zone of

inhibition.

Outcome: Control discs completely covered w/ bacteria, some plant extract create

larger zone inhibition than others, meaning more effective at

lower conc.

Evaluation issues:

Growth unwanted microbes on agar

plates due bad aseptic techniques.

Not shaking extract enough ensure

enough active ingredient.

Inconsistency when add plant

extract to paper discs.

Contaminating controls

Using wrong species bacteria for lawn.

Method