What on earth could link microwave popcorn and cystic fibrosis (CF), a life-threatening inherited disease most common among Caucasians? The additive 2,3-butanedione, also known as diacetyl, a volatile colourless liquid with an intensely buttery flavor.
Diacetyl is produced naturally as a fermentation product by some microbial species and can be found in some beers, as well as artificial butter flavourings and margarine. The US National Institute for Occupational Safety and Health has suggested that diacetyl, when used in artificial butter flavoring, may be hazardous. Workers in several factories that manufacture artificial butter flavoring have been diagnosed with rare lung disease called bronchiolitis obliterans (also known as popcorn worker’s lung). According to Wikipedia, Wayne Watson, a big eater of microwavable popcorn, was awarded over $7 million in damages in 2012, when a jury decided his lung disease was caused by the chemicals in microwave popcorn. In 2012, a paper published in the journal Chemical Research in Toxicology also suggested there may be a link between diacetyl and Alzheimer’s disease (1).
So what has diacetyl got to do with CF? CF is caused by a mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR), leading to a number of symptoms, including chronic lung infections, which often flare up requiring treatment with antibiotics. A paper just published in The ISME Journal reports that diacetyl was found in breath samples from CF patients and healthy controls, but at higher levels in the CF patients (2). The researchers suggest that the low oxygen conditions in the CF lung lead to fermentation by certain microbes, and the increased production of diacetyl. This may in turn cause other microbes to produce toxic compounds and further damage the lungs. The researchers are hopeful that monitoring diacetyl levels in CF patients may help predict flare-ups.
As an aside, I also just read an abstract for a paper (behind a paywall, alas) that claims to be the first description of a bacterial pathogen jumping from humans to plants (3). Andrea Campisano and colleagues report, in the journal Molecular Biology and Evolution, the discovery of a grapevine-associated relative of a bacterium that causes acne in humans, Propionibacterium acnes! They think that the bacterium jumped from people vines during the Neolithic period when grapevines were being domesticated.
2. K L Whiteson, S Meinardi, Y W Lim, R Schmieder, H Maughan, R Quinn, D R Blake, D Conrad, F Rohwer. Breath gas metabolites and bacterial metagenomes from cystic fibrosis airways indicate active pH neutral 2,3-butanedione fermentation. The ISME Journal, 2014; DOI: 10.1038/ismej.2013.229
3. A. Campisano, L. Ometto, S. Compant, M. Pancher, L. Antonielli, C. Varotto, G. Anfora, I. Pertot, A. Sessitsch, O. Rota-Stabelli. Interkingdom transfer of the acne causing agent, Propionibacterium acnes, from human to grapevine. Molecular Biology and Evolution, 2014; DOI: 10.1093/molbev/msu075