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Team:Paris Bettencourt/Project/Old People Smell
From 2014.igem.org
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<p class=text1>We sought to isolate bacterial strains adapted to use 2-nonenal as a carbon source. Such strains could hypothetically be used to actively scavenge 2-nonenal from the skin, neutralizing the smell (Fig. 3). We chose to look for these strains within the natural human skin flora. Human sweat is rich in fatty acids (Callewaert et al. 2014)], and lipophilic phenotypes are common among skin isolates. Natural skin bacteria are pre-adapted to the skin environment, so are more likely to be viable and metabolically active. </p> | <p class=text1>We sought to isolate bacterial strains adapted to use 2-nonenal as a carbon source. Such strains could hypothetically be used to actively scavenge 2-nonenal from the skin, neutralizing the smell (Fig. 3). We chose to look for these strains within the natural human skin flora. Human sweat is rich in fatty acids (Callewaert et al. 2014)], and lipophilic phenotypes are common among skin isolates. Natural skin bacteria are pre-adapted to the skin environment, so are more likely to be viable and metabolically active. </p> | ||
<p class=text1>We prepared minimal 2-nonenal plates and inoculated them with human skin samples. M9 agar plates were prepared with 0.2% 2-nonenal solubilized with 0.05% tween 80. No other carbon sources were present. An inoculating loop was used to streak plates with samples collected from human forehead, hands, and outer nose. In total we sampled 3 body sites from 8 individuals. | <p class=text1>We prepared minimal 2-nonenal plates and inoculated them with human skin samples. M9 agar plates were prepared with 0.2% 2-nonenal solubilized with 0.05% tween 80. No other carbon sources were present. An inoculating loop was used to streak plates with samples collected from human forehead, hands, and outer nose. In total we sampled 3 body sites from 8 individuals. | ||
| + | </p> | ||
| + | <p class=text1>We isolated four bacteria strains capable of growing on 2-nonenal. Colonies appeared after 1 week. The strains were identified by 16S sequencing with universal primers (Box 1, information on each strain). We chose to focus further experiments on Micrococcus luteus as it performed the best in the M9 the 2-nonenal medium.</p> | ||
| + | <p class=text1><i>M. luteus</i> is a natural human skin bacterium and a well-described oligotroph, or nutrient scavenger. Their genome sequence indicates a complete fatty acid degradation pathway, meaning they can plausibly degrade 2-nonenal. | ||
| + | We next sought to characterize the degradation of 2-nonenal by M. luteus. We first identified the smell detection threshold of 2-nonenal. Human smellers could consistently detect 2-nonenal at a concentration of 1000ppm (Fig. 4). | ||
</p> | </p> | ||
</div> | </div> | ||
Revision as of 17:04, 15 October 2014
Smell Like Teen Spirit
| BACKGROUND
|
AIMS
|
RESULTS
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| Introduction | Motivation | Aims | Results | References |
Aims and Achievement
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Fig. 2-nonenal formation in an old-person skin
Introduction
Body odor is affected by age. The existence of a characteristic "old person smell" has been long discussed anecdotally and recently confirmed by experiment. Even untrained smellers can classify age by scent alone (Mitro et al., 2012) The presence of 2-nonenal in body odor is correlated with age and detectable only in people over 40 (Haze et al., 2001).
2-nonenal is an unsaturated aldehyde smelling of orris, cucumber and fat (Floavornet database). It is detectable to the human nose at concentrations as low as 3 ppm (Mitro et al., 2012). The exact source of 2-nonenal in sweat is not known, but it is believed to derive from skin-secreted lipids, oxidized by bacterial lipid peroxidases (Mitro et al., 2012).
The appearance of 2-nonenal in sweat with age has no negative health consequences. The perception of 2-nonenal is subjective, and may be pleasant or unpleasant depending on the smeller and the context. However, "old person smell" can carry a social stigma and some people may prefer to remove it from their body odor for cosmetic reasons. Also, 2-nonenal can be a case study in targeted microbiome modulation. If we can selectively remove this molecule, we may learn to alter other properties of the complex skin surface.
Results
Isolation of strains on 2-nonenal
We sought to isolate bacterial strains adapted to use 2-nonenal as a carbon source. Such strains could hypothetically be used to actively scavenge 2-nonenal from the skin, neutralizing the smell (Fig. 3). We chose to look for these strains within the natural human skin flora. Human sweat is rich in fatty acids (Callewaert et al. 2014)], and lipophilic phenotypes are common among skin isolates. Natural skin bacteria are pre-adapted to the skin environment, so are more likely to be viable and metabolically active.
We prepared minimal 2-nonenal plates and inoculated them with human skin samples. M9 agar plates were prepared with 0.2% 2-nonenal solubilized with 0.05% tween 80. No other carbon sources were present. An inoculating loop was used to streak plates with samples collected from human forehead, hands, and outer nose. In total we sampled 3 body sites from 8 individuals.
We isolated four bacteria strains capable of growing on 2-nonenal. Colonies appeared after 1 week. The strains were identified by 16S sequencing with universal primers (Box 1, information on each strain). We chose to focus further experiments on Micrococcus luteus as it performed the best in the M9 the 2-nonenal medium.
M. luteus is a natural human skin bacterium and a well-described oligotroph, or nutrient scavenger. Their genome sequence indicates a complete fatty acid degradation pathway, meaning they can plausibly degrade 2-nonenal. We next sought to characterize the degradation of 2-nonenal by M. luteus. We first identified the smell detection threshold of 2-nonenal. Human smellers could consistently detect 2-nonenal at a concentration of 1000ppm (Fig. 4).
Fig. Word cloud describing 2-nonenal
Methods
The deterioration of personal odor due to aging may be a serious social problem for some people which would like to keep youth body odor. Moreover, the 2-nonenal smell is mostly perceived as unpleasant, thus people with body odor marked with this compound may undergo unfriendly reactions based on their odor. Therefore, iGEM Paris Bettencourt Team decided to study the 2-nonenal relationship with the human skin microbiome in order to help aged people neutralize their body odor.
References
- ref1- ref2
+33 1 44 41 25 22/25
paris-bettencourt-igem@googlegroups.com 
