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Biofilm Treatment with Polymers

David B. Hedrick davidbhedrick at icx.net
Thu Jul 1 08:57:30 EST 1999


Hello Mary: 
I hope I can help. 
> I am researching topics for my graduate project and my advisor would 
> like to do some work with biofilms. 
> My current work involves the use of polymers as drug treatments and we 
> are just getting into the anti-infective field. It would be nice if I 
> could mesh the two together (or so I thought). 
> When I did a literature search nothing comes up with polymers and 
> biofilms. However through web surfing I have found a number of 
> commercial companies out there that manufacture polymers and use them 
> for treatment of industrial waste water, paper mills, cooling towers 
> etc. 
I would expect the polymers used for drug treatment to be very 
different from those used to treat industrial biofilms. I expect 
drug-treatment polymers either deliver active ingredients dissolved in 
the polymer or have an effect on tissues by the nature of the polymer. 
Polymers used industrially against biofilms are largely competing for 
good bacterial attachment sites on surfaces. Industrial biocides are 
ususally small soluble molecules. Rarely does industry want to make the 
biofilm more healthy. 

> An example of this is Buckman Laboratories, who market a 
> polyionene compound for biofilm eradication. Have any of these 
> companies published their data? 
Companies don't publish data on their products because the ingredients 
are often so simple that customers are tempted to make their own 
product. Also liability exposure. What's in Coke? What's in ice 
cream? What's in shampoo? Coke is carbonated prune juice. You 
wouldn't want to eat store ice cream if you knew it's composition 
(polysorbate 60, anyone? sodium alginate?). Shampoo is so easy and 
cheap to make, they have to put smells and colors and sparkles and lots 
of commercials in it so you perceive a difference. 

> Maybe I am searching in the wrong 
> place, is PubMed an unreasonable place to look for this information? 
Yes. Sounds like a medical database to me. Try Agricola (Latin for 
farmer) at <http://www.nal.usda.gov/ag98/>. Before a high-tech product 
is sold, the research behind it is often in the scientific literature. 
Finding the original research from the company site is like finding your 
girlfriends bra-strap by her mother's instructions. A company site is 
rarely scientific literature. Remember, PR = BS. 
OK. You have to look for the original government funded research that 
this company's product is based upon. Sigh. Go through the entire 
company site, follow every link, look at everything. Write down every 
person's name that appears anywhere. If someone made an important 
discovery that made money, they might still be in the company. If you 
have access to corporate information, get the names of the largest 
stock-holders. Now search the scientific literature for those names. 
Go back and look for names of specific chemical compounds or processes. 
Search the literature for those. You now have a large list of names and 
a large list of chemicals/processes, which in your literature search (I 
like Agricola, Chem Abstracts is comprehensive and sadistic, Biological 
Abstracts is big and obscure, there are others) give you huge numbers of 
matches. Most of those you eliminate by scanning the title. Read some 
of those abstracts, and of those, some of those articles. By this time, 
what you are searching for has changed because you have learned a lot. 
Remember to check in the government documents and patent records. 
Remember to be nice to the librarians. 30 seconds of being polite to a 
librarian could save you days. 
> My 
> thought had been to look at commercially available polymers of differing 
> molecular weight and different charge densities and see what effect they 
> would have on established biofilms. 
The trick in industrial settings (and anyone feel free to correct me, 
I'm extrapolating) is to kill the biofilm with a soluble biocide, then 
protect the clean surfaces with a polymer that competes with the 
bacteria. Attached bacteria are notoriously difficult to remove or 
kill. Much easier to prevent attachment. 

> There is no sense in my reinventing 
> the wheel if the information is out there. Can any of you out there 
> offer some helpful suggestions? Just to clarify, I am not talking about 
> the polymers as surface components but as soluble antimicrobials.
Why use a polymer as an antimicrobial when sodium hypochlorite (bleach) 
works so well? As a drug, bleach has it's limitations. 8^) But in 
industrial water treatment, it's pretty good. 

> Another question (if I may take up some more of your time) was about 
> quantifying biofilms after treatment. I had come across a method that 
> uses crystal violet to stain the biofilm, extracting it with DMSO, and 
> measuring the absorbance in a spec. It appealed to me because of its 
> simplicity and ease of use. Any objections or cautions about this 
> approach?
Cool, if it works on your system. I hadn't heard of that method. I 
usually look for biofilm biomass in systems like soils and bioreactors. 
Don't think it would work on those. 
You started your post with your graduate advisor suggesting you look at 
biofilms. Your medical background blinds you to the biofilms around 
you. Take a glass from your cupboard, fill it with water from your tap, 
and set it on a shelf. There were some bacteria on the inside surface 
of your glass, but they are out-numbered by the bacteria that came with 
your tapwater. Don't worry. The tapwater bacteria are selected by 
their ability to survive hypochlorite, not their infectivity in humans. 
A week later, there is a barely visible scum on the water surface and a 
definite slimeyness on the inside of the glass. 
Soil is a large biofilm thinly spread across the fractal surfaces of 
clay, silt, and sand particles. 
Plant leaves have a biofilm called the phyllosphere. Plant roots, the 
rhizosphere (or rhizoplane, I can never remember). 
Your skin, as well as every body orifice, has it's own microbial 
community. 
So does every other animal. And plant. 
Biofilms can increase or decrease the corrosion of metals. 
There are lots of biofilms out there, and we don't have any idea most 
of what's going on. 
I hope I was of some help. 
> Thank you in advance for your replies. 
> Mary Pitruzzello 
> pitruzzello at mediaone.net
-- 
Or, you could hire me.
~DBH
Technical writing, literature search, and data analysis at the interface 
of chemistry and biology. 
davidbhedrick at icx.net
David B. Hedrick 
P.O. Box 16082 
Knoxville, TN 37996

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