Volume 40, Issue 6 (November 1995)
In-Vitro Production of Ethanol in Urine by Fermentation
Driving while under the influence of alcohol (DUI) can lead to serious injuries to the intoxicated driver and surrounding individuals, in addition to revocation or suspension of driving privileges. The accuracy and interpretation of the testing procedures may be compromised if an individual's urine contains sugar, and either bacteria or yeast. Under these conditions, ethanol can be produced in vitro, producing a result that may be erroneously indicative of DUI. In this study three yeast species and six bacterial species were added to a blank urine sample devoid of any alcohol or sugar. Samples were incubated at 0, 25, and 35°C for 24, 48, and 144 hours in the presence of one of four different sugars. Ethanol concentrations were assayed using an enzymatic alcohol dehydrogenase assay. Results showed that when glucose was used as a substrate, all yeast species (Candida albicans, Candida parapsilosi, and Candida sp. not albicans) and three bacterial species (Klebsiella pneumoniae, Escherichia coli, and Proteus mirabilis) were capable of producing ethanol while the other three (Enterococus sp., Staphylococcus sp. not aureus, and Pseudomonas aeruginosa) were not. The rate of ethanol production is temperature dependent and can be inhibited by storage of samples at 0°C or the use of approximately 1% sodium fluoride as an antimicrobial agent. Many of these species were also able to use other substrates (sucrose, fructose, and galactose) to produce ethanol by fermentation.