Team:GZ HFI/Background

Background | iGEM GZ_HFI


Social Demands

Social Embarrassment of Fart

Farting is a normal physical phenomenon that is embarrassing due to its acrid smell. We released an online survey to investigate the general public's attitudes towards farts. We received a total of 324 valid answers. 83% of them said they are bothered by stink fart, and two-thirds of them were willing to intake a bio-agent that could eliminate fart odor temporarily, suggesting that the social embarrassment and disturbances in interpersonal relationships caused by stink fart was a big social issue.

Social Distancing of patients who undergo enterostomy

Worldwide, colorectal cancer is the third most common type of cancer in men and the second in women (American Cancer Society, 2011). Colorectal cancer-related mortality rates have gradually but steadily declined over the years, and the relative survival rate at 5 years is currently 64.3% (Edwards, 2010). An estimated 18%--35% of Colorectal cancer survivors have received temporary or permanent intestinal ostomies as part of their cancer treatment (Schmidt, 2005; Gastinger, 2005). Enterostmoy surgery is a life-saving procedure that allows bodily waste to pass through a surgically created stoma on the abdomen into a prosthetic known as a 'pouch' or 'ostomy bag' on the outside of the body or an internal surgically created pouch for continent diversion surgeries. According to the data estimated in 2005, China has a total of one million patients who undergo permanent enterostomy surgery, and that number is increasing by 10,000 annually (Dehong, 2005). However, all studies demonstrated that living with an ostomy influences the overall quality of life negatively (Vonk-Klaassen, 2016). The ostomy-related difficulties most commonly reported are painful peristomal skin conditions and severe body odor (Lynch, 2008). In the study of Diébold et al, while enterostomy has improved the survival rate of patients with colorectal cancer up to 5 percent, the postoperative body odor caused by the change of defecation pathway still poses great challenges to patients' social lives (Diébold, 2016; Zhang, 2020). These patients may use an ileoanal pouch, which is a pocket attached to the artificial anus, to collect the excretion and to block out the heavy intestinal odor, but the pouches are at risk of leakage, which could result in an acrid odor.

Therefore, we envision developing a capsule containing the genetically engineered E.coli to eliminate the acrid odor molecules in the intestine. In this way, enterostomy patients can endure less social embarrassment.

Main Chemicals

99% of intestinal gas is composed of odorless gas: N2, O2, CO2, H2, and CH4, so less then 1% of the intestinal gas contributes to the acrid smell of fart (Levitt, 1971). Among the 1% odor gas, ammonia accounts for the greatest proportion and hydrogen sulfide the second (Hunde, 2012; Gemert, 2003; Deng, 2015).

Since ammonia and hydrogen sulfide are the main contributors to the acrid smell, we endeavor to engineer probiotics living in the intestine to temporarily lower the ammonia and hydrogen sulfide level and to produce myrcene to mask the unpleasant order.


American Cancer Society. (2011). Global cancer facts & Figures 2nd edition 14-01-2015.

Dehong YU. Enterostomal therapy in China:status and advances. Chin J Nurs 2015;40(006), 415-417.

Deng YF, et al. Prebiotics mitigate in vitro sulfur-containing odour generation in caecal content of pigs. Ital J Anim Sci 2015;14(1):2015-3762*.*

Diébold L, et al. Shame and specular image: experience of colostomy in colorectal cancer. Psycho-Oncologie 2016;10(2):128-35.

Edwards BK, et al. Annual report to the nation on the status of cancer, 1975--2006, featuring colorectal cancer trends and impact of interventions (risk factors, screening, and treatment) to reduce future rates. Cancer 2010; 116: 544-73.

Gastinger I, et al. Protective defunctioning stoma in low anterior resection for rectal carcinoma. Br J Surg 2005; 92: 1137-42.

Gemert LJV. Compilations of odour threshold values in air, water and other media; Boelens Aroma Chemical Information Service, 2003.

Hunde A, et al. Supplementation of poultry feeds with dietary zinc and other minerals and compounds to mitigate nitrogen emissions-a review. Biol Trace Elem Res 2012;147(1-3):386-94.

Levitt MD. Volume and compo­ sition of human intestinal gas. N Engl J Med 1971;284(25):1394-8.

Lynch BM, et al. Stoma surgery for colorectal cancer: A population-based study of patient concerns. J Wound Ostomy Continence Nurs 2008;35(4):424-428

Schmidt CE, et al. Prospective evaluation of quality of life of patients receiving either abdominoperineal resection or sphincter-preserving procedure for rectal cancer. Ann Surg Oncol 2005; 12: 117-23.

Vonk-Klaassen SM, et al. Ostomy-related problems and their impact on quality of life of colorectal cancer ostomates: a systematic review. Qual Life Res 2016; 25: 125-33.

Zhang X, et al. Effects of hospital‐family holistic care model on the health outcLome of patients with permanent enterostomy based on the theory of 'Timing It Right'. Int J Older People Nurs 2020;29(13-14):2196-208.

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