IGEM:MIT/2006/System brainstorming/Scent subprojects

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introduce the minty fresh smelling coding region/enzyme into an already discovered genetically engineered strain of Streptococcus mutans bacteria so that bacteria that are already present in your mouth will produce good breath odor whenever you eat sugar (actually, specifically refined sugar, i.e. sucrose).


Try to regulate the system with sucrose (or dextran**) so that the presence of sucrose (or dextran the extracellular goo) selectively turns a switch "ON" for intracellular production of salicylic acid (or whatever is needed to activate the desired scent producing enzyme). This way, if you don't add the refined sugar, you have regular smell -- but if you do add the refined sugar, get a temporary wintergreen smell.

    • NOTE: Dr. Hillman says that monomeric sugars are actually preferable from a health and tooth decay standpoint. While they can be metabolized to lactic acid (which erodes enamel), many of them, such as galactose, are slowly metabolized and also yield other, non-acidic end-products. The main problem with refined sugar (sucrose) is that, in addition to being rapidly metabolized to lactic acid, it is the substrate [precursor, or component needed to make a new molecule] for an extracellular goo called dextran that helps to trap the acid next to the tooth surface. so the tooth winds up getting a more prolonged acid insult.


By applying this to Streptococcus mutans bacterium (this is already a natural part of your mouth's ecosystem), minty breath could be controlled by eating sucrose and by a sensing/secreting device that WE engineer!


Streptococcus mutans, a bacterium that inhabits the human mouth, causes cavities by converting sugar into enamel-corroding lactic acid. Dr. Jeffrey D. Hillman of the University of Florida College of Dentistry in Gainesville has developed a genetically modified strain of the bug that doesn't make lactic acid, but is able to shoulder out competing bacteria. The new bacterium, dubbed BCS3-L1, could prevent cavities by colonizing the mouth and getting rid of its cavity-causing cousin. This new GM "good bug" was publicly announced in 2002 and experimental treatment has been successful in animals. Also it was approved for human trials by the FDA in 2004, and is currently in phase I of those trials. Funding has been secured and this new product is proposed to be on the market by 2008.

Currently, the cavity industry supplies dentists with nearly half of their annual income (around 27 billion dollars). Sucks for dentists, i guess, but its pretty cool that cavities may soon be eliminated (think 3rd world countries), but why not eliminate bad breath in the american sucrose-consuming population as well?

It seems to me that there is a high likelihood that OraGenics will succeed in getting their new mutant strain of Streptococcus on the market. While they are working on that, I think it would be cool to further play with this bacteria -- i.e. introduce the scent enzyme into this bacteria and control the enzyme's activity through sucrose levels. Hopefully it would work and could potentially become an added bonus to their new gel/mouthwash product

Also, it looks like i'm not totally out of my mind because the 2005 team thought of something similar --- but I don't think that they knew about streptococcus mutans, so maybe the challenge would be getting this system working in this cellular organism (if that is feasible) because it may be of marketable interest

Check out from 2005: < IGEM:MIT | 2005 Somehow, if we can get mouth bacterial cells to take up R(-)carvones (spearamint) and excrete it shortly after encountering food (glucose?) <-- looks like a glucose-sensing-carvone-excreting experiment to me. Possible problem might be getting both enantiomers of the compound. Which would give us some gingergrassy smell. Mmm, better than bad breath, eh?

Methyl salicylate is probably easier to make. Check out this reference:

Negre F, Kolosova N, Knoll J, Kish CM, Dudareva N. Novel S-adenosyl-L-methionine:salicylic acid carboxyl methyltransferase, an enzyme responsible for biosynthesis of methyl salicylate and methyl benzoate, is not involved in floral scent production in snapdragon flowers. Arch Biochem Biophys. 2002 Oct 15;406(2):261-70.

This article captures the last stage of synthesis and expresses it in E. coli. Salicylic acid is supplied exogenously.


1. This one is from Nature, about the discovery of odor- eating bacteria: http://www.nature.com/bdj/journal/v199/n4/full/4812689a.html

2. This one describes is an 'old' publication, but tells about the genetic engineering of BCS3- L1 (a new strain of streptococcus mutans), which leads me to think that this system does support genetic manipulation: http://www.newscientist.com/article.ns?id=dn1941

3. This one proves that the cavity fighter was approved for human testing in 2004, and that the dental treatment does, in fact, use genetically modified bacteria. This describes the success of animal trials. It also gives the details of the phase 1 testing that is currently being conducted in humans http://msnbc.msn.com/id/6629884

4. This is a good look at safety concerns: http://www.wired.com/wired/archive/10.06/start.html?pg=11

5. This has Q and A from the lead Dentist/Scientist Dr. Hillman who has dedicated over 25 years to this research-- and more about dextran goo http://www.healthmantra.com/ypb/jan2002/caries.htm

6. This is a detailed (long) company profile for OraGenics Inc. http://sec.edgar-online.com/2004/03/17/0001144204-04-003117/Section2.asp

7. I think that this is a really good concise summary of most of the relevant ideas/issues: http://www.oragenics.com/product_replacement.php


If sucrose or dextran is not a good sensing system, or if designing a oral system is not good for some reason, could maybe apply to foot odor and do a similar sensing/secreting control system with the trigger being something other than a sugar (some enzyme in sweat??? moisture???). Normal foot microbial flora is very similar to that of the mouth.


IDEA: create a benign bacteria (possibly regulate its growth) that is programmed to smell good when urinated on. Urine is a source of salicylic acid, and the methyl transferase step is dependent on salicyliic acid, so it seems like urine "on or off" would be a pretty easy way to control the scent producing enzyme activity of our engineered insert. This bacteria could then be prepackaged into cat litter, small animal bedding, bulk horse shavings, etc. to help with odor control


1. Salicylic acid and equine urine measurements: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3608958&dopt=Abstract


IDEAS, IDEAS, IDEAS: I know we thought about making e.coli systems with light sensitive controls, time sensitive controls, heat/concentration/moisture sensitive controls, etc......... Also, we talked about multiple scent capacity, yeast transformation, biological air fresheners/ornaments, scented bread and beer, and stationary phase reporter systems ---- do you guys want to look into whichever of these you (personally) like the best and/or think of and post other subproject ideas that you may have come up with tonight???? I think that this was our plan right??? okay, goin to sleep now... see you all in the a.m.