I must admit that my interest in Mozart has mostly focused on the various theories of his demise in the prime of his youth. The composer had always been sickly, and it is well known that he had often been treated with antimony compounds by his physicians. He even dosed himself when he didn’t feel well. Antimony compounds can indeed be lethal if the dose is high enough. Recently, though, my curiosity about Mozart has taken a different turn. I’ve become interested in his music. Not because I’ve suddenly developed an appreciation for his sonatas. Frankly, I’d rather listen to Les Miz, Camelot or Phantom. But it is the effect of Mozart’s Flute Quartet in D major that has drawn my attention. Not on me, but on same laboratory mice.
One of the hottest areas of research these days is the microbiome, that complex ecosystem in our gut comprised of hundreds of bacterial species. The trillions of bacteria that inhabit our digestive tract, mostly the large intestine, are not just bystanders. They play an active role in breaking down plant fiber and proteins, synthesizing some vitamins, teaching the immune system to distinguish friend from foe and producing short chain fatty acids that help regulate inflammation. They even control insulin sensitivity and can influence mood, cognition and behaviour. And now we learn that the composition of the microbiome may be affected by music, specifically Mozart’s. At least in female mice.
A paper in the journal Microbiology Spectrum has the alluring title, “Music exposure enhances resistance to Salmonella infection by promoting healthy gut microbiota.” Infection by foodborne Salmonella enterica is decidedly unpleasant, causing diarrhea, cramps, fever, nausea, and vomiting within a day or two of exposure. The affliction usually lasts less than a week but in rare cases the bacteria can invade the bloodstream requiring antibiotic treatment. Unfortunately, the effectiveness of antibiotics can be compromised by the emergence of antibiotic-resistant bacteria worldwide at an alarming rate. That’s why any intervention that reduces the risk of salmonella infection is obviously welcome.
Back in 1993, a paper published in the journal Nature reported that students who listened to a Mozart sonata for ten minutes performed better on spatial reason tests such as folding paper into different shapes than students who sat in silence. The media jumped on the findings and characteristically blew the study’s results out of proportion, even suggesting that listening to Mozart made the students smarter. That unleased a craze of playing recordings of Mozart by parents in babies’ rooms with hopes of boosting their offspring’s intelligence. The fact is that the original findings were never reproduced, with critics suggesting that listening to music improves mood which in turn leads to better performance having nothing to do with increased intelligence. The “Mozart effect,” as it came to be called, did however spur further research including in animals.
A 1998 study found that rats listening to Mozart solved mazes faster and with fewer errors than mice that had to tackle the problem in silence. Such studies then prompted investigations of other possible effects that music might have, such as on the microbiome. Adult mice were exposed either to white noise or Mozart’s Flute Quartet for three weeks after which their stool was collected and analyzed for bacteria present by gene sequencing. The Mozart mice showed changes in the composition of their gut bacteria, particularly an increase in Lactobacillus salivarius. This bacterium ferments sugars into lactic acid that then lowers the local pH making it harder for other bacteria such as E. coli, Clostridium difficile and Salmonella to survive. Furthermore, Lactobacillus salivarius produces antimicrobial peptides called salivaricins that disrupt the cell walls of potentially disease-causing bacteria.Â
When the mice were challenged with Salmonella bacteria, the ones that had been listening to Mozart exhibited less colonization and reduced risk of infection. To show that this was really due to the proliferation of Lactobacillus salivarius, the researchers administered this bacterium to mice, entertained them with Mozart’s music, and then tested their poop. Indeed, the protective bacteria had significantly multiplied!
What is our takeaway here? If you are an adult female mouse and had been picked up by a scientist who thrust salmonella bacteria down your throat, you might reduce your chance of feeling unwell by listening to Mozart’s Flute Quartet in D major. But if you are a human, and are unlucky enough to have consumed pistachio nuts from a batch contaminated by Salmonella before learning of Health Canada’s recall, I don’t think there is much point in asking Alexa to help you by playing Mozart. Still, that would be better than taking antimony as would have been recommended in Mozart’s day.
