I am through with the past.
I have remembered my shortcomings, and my father’s, remembered how I loved him and was loved by him, and in so doing I have attempted to resurrect a time that once was. I have longed to be enveloped in the living I knew in New York, not because it was all that much fun, but because it is my past. And that past is forever linked to the past that came before it, back to a time when I was a kid and life was harmless and I was loved. What I am left with is a visit from the past. And a visit is nothing more than a little death.
Ghosts inhabit this world.
The End
I know that we are going to destroy the world that holds us. We are savages, treating the Earth like a toilet, fouling our own nest. We all seem to agree on that now. Our heads have been in the sand since I was a little girl, when we first realized how good we had it and how we were screwing it all up. We knew what we were wreaking and it scared us, most of all because we couldn’t see any way of stopping it. So we stick our heads in the sand. The ostrich does this not to become invisible to its foe; it wants to avoid seeing what’s coming for it.
What I created will not stop our destruction of the world. What I am doing here at Forest Garden will not make a difference either, but I have no choice. I acted in New York because I cared, and I have to act now because it matters to me still. The world will continue to change, probably for the worse, but it remains a beautiful place to be. And there is hope, people hold on to hope, even the most pessimistic. Leroy and Rachel see, like the rest of us, where we’re headed, yet they chose to have a child. They must believe that we can right our wrongs or why would they have done that?
I look out my window onto a sunny morning. It snowed yesterday and all the night too, and the sunlight on the snow is brighter, but in a different way, than on a summer day. It’s hard to be pessimistic on a morning with that sun, the snow still clean, and the birds gliding in the light. Why not love this morning? I stretch. The bay continues to empty and refill twice each day in sync with the moon.
A crow flies overhead. Black, sleek, it reminds me of Lina. It looks down, its beak pointing to the ground. It’s the birds that give me heart to continue. Birds keep doing what they do, colourful and tenacious, while the world burns.
I stoke the fire I had left to die out and lie down on my bunk. Leroy’s premonition came partly true. We both live in Canada. My skates are hanging from a nail on the wall. “We make things happen by believing they will,” he once said to me. “We dream where we’re headed, and one day, as if entering that dream, we arrive there.”
I’m the one in the cabin in the woods, alone on a peaceful sunny morning. I jump from the bunk, lace up my boots, put my coat on, grab the skates from the nail on the wall as well as my shovel, and leave the cabin. I walk deep into the forest beside coyote tracks in the snow along the woods road. The tracks come to a pile of rabbit pellets and a rabbit track crossing it perpendicular to the road. The coyote tracks veer off to follow the trail of the rabbit heading into the woods.
The pond is solid and covered with snow. Its edge is rimmed with spruce laden with snow and with the skeletons of maples, highlighted by the white that rests along their stiff branches. I lace up my skates and begin to shovel the ice clear. It becomes the shape of a rink in a fairy tale, all curves and blips and narrow bottlenecks between trees that lead into open spaces. The shovelling warms me up and I throw my coat on the snowbank I just made. I rest my bare palms on my sweater, feeling the comfort of wool and the solid flesh of my healthy body, and look up at the sky. It is blue as only a sky in January can be blue, outlining the spires of the trees that pierce it. I thank the sky, and the sun that casts shadows of branches on the snow and ice, and the cold air that fills my lungs.
We won’t survive. That’s no reason to stop trying though, no reason to stop caring. There’s nothing else we can do.
I begin to skate, feeling the smooth ice beneath my blades.
Some things won’t be lost.
Creation and Characterization of a Polyethylene Terephthalate-Digesting Mutant of Pseudomonas aeruginosa
Benita R. Mosher, Jonathan Yovkov, Melvin A. Leach*
Department of Microbiology, Cornell University Medical College, New York, New York
Received 6 December ___ /Accepted 12 February ___
Polyethylene terephthalate (PETE), like many petroleum-based polymers, has a half-life of natural degradation exceeding millennia. We report here the creation and selective cultivation of mutant strains of P. aeruginosa capable of survival on media containing PETE as the sole source of carbon. These strains apparently cleave PETE in liquid culture, resulting in ethylene glycol as well as other, as yet unknown, short-chain organic compounds. Preliminary analysis of the enzymatic function suggests a novel esterase activity.
Polyethylene terephthalate (PETE) is a condensation polymer resulting from the transesterification of dimethyl terephthalate and ethylene glycol, with methanol as a by-product (Fig. 1). It is one of the most important synthetic polymers and is used in the manufacture of bottles to contain soda and water, food containers, and other liquid containers.
Given its near ubiquity, stability once discarded, and the failure of recycling programs to capture more than 20 per cent of manufactured containers (3), a means of eliminating this waste product from landfills, ditches, and the waterways of the world is essential. There has been a report of a strain of Pseudomonas that eats high-density polyethylene (1) but this has not been confirmed.
FIG. 1. Chemical synthesis of polyethylene terephthalate from dimethyl terephthalate and ethylene glycol. The enzymatic breakdown, presumed to be via esterase function in the mutant strains BRM92 and BRM106, releases ethylene glycol and other short-chain compounds yet to be identified.
As part of our ongoing pursuit of sustainable solutions to this problem, we have engineered and/or selected for strains of P. aeruginosa (6) and S. aureus (2) that are capable of exploiting carbon held within the long-chain polymers that make up various plastics.
We found these strains to be minimally effective in degrading synthetic polymers in liquid culture. Wanting to expand on this work and, hopefully, to discover strains capable of rapidly and efficiently digesting plastics, we used mutagens to create cells with altered properties. These techniques were accompanied by screening and selective pressure to unequivocally identify mutants with the enhanced characteristics.
Through random mutagenesis and selection, we have created a strain of P. aeruginosa capable of rapidly degrading PETE in vitro into ethylene glycol and terephthalate.
MATERIALS AND METHODS
Organism. Pseudomonas aeruginosa strain K212 (5) was the wild-type strain used in this study. It was treated with mutagens, followed by selection, resulting in two PETE-digesting strains: BRM92 and BRM106.
Culture conditions. Single colonies of randomly mutated cells of P. aeruginosa K212 were grown in 2X LB medium containing 100 μg/ml carbenicillin and 35 μg/ml tetracycline in 100 ml Erlenmeyer flasks. Cells were spun, washed 3X in distilled water, and resuspended in distilled water containing minimal broth with 100 μg/ml of PETE as the only source of carbon. These liquid cultures were incubated at 300C, observing for cell growth. Cultures not exhibiting any turbidity were discarded after seven days.
Chemicals. Ethyl methanesulfonate (EMS) was purchased from Blako Chemical Co. (St. Louis, MO). Acridine was purchased from McNeil & Sons Industries (Cleveland, OH). γ-rays were applied using cobalt-60 supplied by Atomic Energy of Canada Ltd. (Chalk River, ON). A circular film of PETE (diameter 65 mm and approximately 750 mg) was obtained from DuPont. Mutagenesis. Liquid cultures of strain K212 were subjected to mutagenesis with each of the agents listed above. They were then grown in minimal broth with PETE. Incubations. 1 ml samples of mutated cells of strain K212 growing in minimal broth with PETE as the sole source of carbon were analyzed using reversed-phaed HPLC. The presence of ethylene glycol was used as a preliminary indication that PETE was being degraded. Those liquid culture
s containing significant concentrations of ethylene glycol (>30 mol/L)were subjected to column chromatography.
Detection of PETE-degrading activity using reversed-phase high performance liquid chromatography (HPLC). The liquid cultures were analyzed in a Varian ProStar HPLC system. The polar mobile phase used trifluoroacetic acid as an eluent. The eluent had a flow rate of 0.7 ml/min. The column temperature was kept at 32°C.
RESULTS
Random mutagenesis and selection of P. aeruginosa K212. Two cultures of mutagenized K212 grew in minimal liquid media containing PETE as the sole source of carbon. Strain BRM92 resulted from mutagenesis with EMS and strain BRM106 resulted from mutagenesis with gamma rays. Fig. 1 shows the growth profiles of the wild-type and two mutant strains.
FIG. 2. Growth of P. aeruginosa strains in minimal liquid medium containing PETE. Strains K212, BRM92, and BRM106 were precultured at 30°C for 2 days in 2X LB medium, triple washed with distilled water, and inoculated into fresh minimal medium with PETE as the sole source of carbon. Cultivation was continued under the same conditions for 80 hours. Cell densities were measured by optical density at 600 nm.
Characterization of strains BRM92 and BRM106. Lysates of the two mutated strains showed significant degradation products of PETE (Fig. 2). A large peak corresponds to ethylene glycol, one of the expected products of PETE digestion. A smaller significant peak represents terephthalate. There are many other, smaller, peaks representing products that have not yet been analyzed.
FIG. 3. Chromatogram of PETE degradation products. A lysate of strain BM92 was incubated with PETE for 4 hours at 32°C. Peak 1 is ethylene glycol. Peaks 2 is an unknown degradation products to be analyzed. Peak 3 corresponds to terephthalate.
DISCUSSION
In this paper we report the creation of two strains of P. aeruginosa capable of growth on medium containing a synthetic compound previously impervious to biological attack. The strains rapidly degrade PETE in vitro into ethylene glycol and terephthalate.
This is a significant find because of the potential to utilize such strains in the degradation of waste products currently disposed of in landfills.
It will be interesting to determine the genetic alteration behind the supposed enzymatic changes that allow these bacterial strains to digest a xenobiotic compound.
ACKNOWLEDGEMENTS
We thank Gabriel Nawthorn and Leroy Timmins for critical reading of the manuscript.
REFERENCES
Entwistle, J., Townsend, P., Daltrey, R., and K. Moon. 1976. Strain of Pseudomonas aeruginosa capable of eating vinyl LPs also digests high-density polyethylene. J. Irreprod. Res. 48:38-41.
Foss, T.L. and M.A. Leach. ____. Selection of strains of S. aureus for ability to exploit the carbon in polyethylene. J. Biochem. Fund. 27:215-222.
Burn, S.M. 1991. Social psychology and the stimulation of recycling behaviors: The block leader approach. J. Appl. Soc. Psych. 21:611-629.
McNeil L., and M. A. Leach. ____. Purification and characterization of an extracellular manganese peroxidase from Pseudomonas aeruginosa. Microbiol. Symp. 57:62-69.
McNeil L., Foss, T.L. and M.A. Leach. ____. Selection for strains of P. aeruginosa competent at utilizing long-chain polymers as a source of carbon. J. Biochem. Fund. 25:356-361.
* Corresponding author. Mailing address: Department of Molecular Biology and Genetics, Cornell University Medical College, 1300 York Avenue, New York, NY 10021.
Acknowledgements
All of the characters in our dreams — all the lakes, guns, beasts, and other strange stuff — are aspects of ourselves. We inhabit our dreams in various guises, wearing the cloak of an old girlfriend, a crow flying overhead, or the wood stove that heats our cabin. This book is one such dream.
Books and quotes
The Oppenheimer quote at the beginning is from Joyce Nelson’s The Perfect Machine: TV in the Nuclear Age, 1987, published by Between the Lines, Toronto.
The Wendell Berry poem is from his A Timbered Choir: The Sabbath Poems 1979-1997. Permission to quote granted by
Counterpoint Press.
An Accidental Monk is a wonderful book by Marylee Mitcham (1976, published by St. Anthony Messenger Press) that buoyed me through a winter in the woods in Nova Scotia. She gave me permission to quote from it. Her blog is at anaccidentalmonk.blogspot.com.
Darkness Visible is William Styron’s memoir chronicling his depression. It helped me realize that the pain of losing a parent at a young age can lead to depression. I knew it was debilitating; I continue to see the myriad ways in which that manifests.
People
I am grateful to my editor, Bethany Gibson, for her diligent assistance. I am especially thankful that she championed my novel to the folks at Goose Lane and convinced them to take a chance on it, and on me. She good-naturedly read draft after draft, never seeming to tire of my questions. Thanks, friend.
Thanks to the many who were willing to read and provide comments on early versions of this book. They include Ben Gallagher, Sarah Selecky, Bill Kowalski, Heather Jessup, Eric Philpott, Greg Georgas, Patrick Murphy, Chai Duncan, Erin Robinsong, Ann Macklem, Julie Paul, Angela Klaassen, Annie Bray, and Mavis Spencer.
I have such gratitude for the generosity of Crane Stockey, who hosted me in his boat house on the Northwest Arm. That time alone to write was luxurious, peaceful, and inspirational.
The Writers’ Federation of Nova Scotia is a wonderful organization. It was their Atlantic Writing Competition that gave me a boost when I needed it. Thank you especially to Nate, Sue, and Susan.
I have been in good hands ever since Susanne Alexander and everyone else at the Goose said yes. Thanks for treating me so well and with such enthusiasm.
Thanks to the Wired Monk Writers Group — Dina Desveaux, Chris Benjamin, and Simon Vigneault.
The Nova Scotia Department of Communities, Culture & Heritage has been generous with their support of two Creation Grants during the completion of the manuscript.
For two of the many older men who have mentored me: Con Enright, for teaching me to garden, and Bob Philips, for sharing his stories. The writing of fiction is a way of raising the dead.
Thanks to the owners and baristas of The Trident Booksellers and Café in Halifax, who provided a peaceful respite from city life, pots of Dragon Phoenix Pearl, and an uplifted environment in which to read The New Yorker and write. Their efforts to awaken us to the plight of the environment are an inspiration.
Thanks to Helen Brown for the joy, work, and struggle of life in Halifax; on Hornby Island; and, especially, at Forest Garden. Without that, at least half of this story wouldn’t be.
To my neighbours on the North Mountain, who were nothing but polite, helpful, and supportive as we hacked, swatted, dug, sawed, and nailed our way onto that piece of land.
To my siblings, John, Jill, and Alexa; to Hazel; thanks for supporting me and caring about me and sharing so much.
To my loving, devoted parents. Despite their flaws, they were and are heroic. It is heroism based in simple things: home-cooked meals, tucking children in nightly, keeping a garden, and month-long camping trips to experience the natural beauty of our continent. The consistency and commitment that good parenting requires are more difficult to maintain than writing a book or probably anything else. They were and are very good at it.
To Annie and Ruth, for keeping me company.
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