Week 7: UNC-CH "tagged"

UNC "tagged" : purpose is to "give" a simple lab procedure, a "gift" from an alumni, which if used wisely could help degrade the plastic waste problem, and may or may not refute the claim that "Every plastic bag can take 1000 years to degrade" .

Though not necessarily a solution to our reliance on petroleum, the source of plastic material, it's a start, and attempts to focus on solution rather than the problem.

The tagging began last Friday afternoon when all the students have retreated to their dormitory or to the nearby bars to celebrate the weekend. I was scoping the place for a spot to put the work--

A board containing graffiti work plus the lab procedure below.

I found a likely spot, the Wilson Library (the Biology center) right across UNC's landmark the Bell tower.

I would have left the work up on Fri but the wind blew it down. So I decided, it's better to do it on Sunday night fresh for Monday's eager faces.

Good thing too, as a tornado swept the neighboring town and would have wiped my efforts clean.

So Sunday night, after an adventurous run, around 8 pm I crept my vehicle to a nearby parking lot. Looking completely nonchalant, I placed the "tag" to the site and headed home.

How to isolate polyethylene degrading microorganisms:

Equipment needed:

1. polyethylene film (supermarket plastic bags) or another type of plastic

2. pestle and mortar

3. NaCl (table salt)

4. fine sieve mesh

5. (NH4)2SO4 (Ammonium Sulphate)

6. NaNO3 (Sodium nitrate)

7. K2HPO4 (Dipotassium Phosphate)

8. KCl (Potassium chloride)

9. MgSO4 (Magnesium sulfate)

10. flasks (1 – 3)

11. an incubator with a shaker or rocker

12. filter paper

1) Preparation of polyethylene powder.

Prepare a mixture by grinding 3g of cut polyethylene film and 3g of NaCl (salt) for 10 minutes using pestle and mortar. Transfer the mixture of ground polyethylene film and NaCl into a cylinder containing distilled water. Collected the floating layer of polyethylene particles on filter paper, wash three times with distilled water, and dry it in an oven at ~60°C overnight. Passed the dried polyethylene powder through a sieve mesh (N0100).

2) Preparation of growth and enrichment medium.

The rationale behind the enrichment procedure is to create strong selective conditions using powdered polyethylene as the only source of carbon. Prepare a growth medium consisting of 0.1% (NH4)2SO4, 0.1% NaNO3, 0.1% K2HPO4, 0.1% KCl, 0.02% MgSO4, and 0.01 % yeast extract in 1L of tap water. Then add 0.2g of polyethylene powder to 100mL of growth medium.

3) Isolation of polyethylene degrading microorganisms by enrichment procedure.

Collect soil samples from local landfills, mix together, and use as a source of potential polyethylene degrading microorganisms. Add 1g of the soil mix to the first enrichment flask and incubate at ~30oC for 4 weeks on shaker (200rpm). Take 10mL of broth from the first enrichment flask and re-inoculate into 100mL of fresh enrichment medium, then cultivate under the same conditions for 4 weeks. Repeat the same procedure a third time. Filter the final enrichment culture (FEC) through filter paper to remove any remaining polyethylene powder.

Once you've isolated a polyethylene degrading microorganism measure its effectiveness and then allow to replicate and repeat the process.