What Lives In Your Water?New MdBioLab Activity

G. Houston-LudlamGraduate Student

CBMG, UMCP

Our Activity• Step 1- Collect water

samples– Field trip or Homework

• Students should work in pairs

• Will require a “collection kit”– Clean plastic bottles– Gloves– Ziplocs for ice and

containment of sample

http://ian.umces.edu/imagelibrary/albums/userpics/10025/normal_iil_ian_bf_395.JPG

Our Activity

• Step 2- Filter water samples and culture overnight– 2 different volumes

• 10 ml• 100 ml• Allows for best

opportunity to get a countable plate of 20-60 colonies

http://www.umesc.usgs.gov/aquatic/drug_research/capabilities.html

Our Activity

• Step 3- (Next Day) Count Colonies

Example of bacterial growth on selective media. Photo courtesy of Hornor Lab, Anne Arundel Community College, Arnold, MD.

Equipment Setup• Completely assembled

filtration apparatus• Water samples in ice

bucket• Field data sheet• Sterile 10 ml syringe or

pipet• Beaker with ethanol

holding forceps• Sterile paper filter

Place Filter 1

• Peel cover off filter (best done by instructor or partner)

• Grab edge with sterilized forceps

Place Filter 2• Place paper filter grid

side up on top of metal screen

• Paper must completely cover screen to get proper filtration

Reassemble Filtration Apparatus

• Place filter funnel on top of paper filter

• Clamp glassware in place

10 ml Sample

• Wet filter with 10 ml sterile, distilled water– Water removes static

from syringe• When the water has

suctioned through filter, apply 10 ml of water sample to filter

Wash Filter Funnel

• With clean syringe, wash the sides of the funnel to get any splashes

Remove Filter

• Unclamp filter funnel• Grab edge of filter with

sterile forceps and break vacuum seal

Place on Plate

• Hold plate tilted downward and away

• Place filter at bottom edge of plate

• Roll onto media to minimize bubbles

• Cover and incubate 24 hrs

Repeat for 100 ml

• Place new filter on filtration apparatus

• Wet filter and suction through

• Pour 100 ml into funnel• Wash sides of funnel• Place filter on media

After Incubation• This is what the students will

see after a 24 hour incubation at 41˚C (chicken body temperature)

• Left-hand plates came from Patuxent River

• Right-hand plates came from Warehouse Creek off South River

• Top plates are 10 ml, bottom plates are 100ml samples