To both relieve those patients' dilemmas and prevent healthy people from the embarrassment of farting, we intend to genetically engineer probiotic Escherichia coli to decline the production of the main molecules that contribute to the acrid smell (ammonia and hydrogen sulfide) and produce an aroma substance (myrcene). We mutated argA into argA^fbr and knocked out argR to enhance the conversion of ammonia into arginine; createed several mutants of cysE gene to promote the conversion of hydrogen sulfide into cysteine; and constructed a system of three plasmids containing essential genes to produce myrcene. The results showed that, compared to the control groups, the expression of argA^fbr plasmid along with △argR genome significantly improved the bacteria's ability to absorb ammonia compared to the control groups. Cysteine synthesis was improved apparently by the expression of mutated cysE genes. Besides, engineered E.coli produced myrcene successfully but with relatively low production.
