Toilet paper used by artist Billy Apple nearly 50 years ago has given Liggins Institute researchers new insights into how the gut microbiome changes over time.
Last year, after Apple heard of the microbiome research, he offered up the three samples he’d taken during toilet stops on three successive days – along with three new samples, also taken on consecutive days.
Scientists were then able to genetically identify the bacteria in each of the samples and establish how they’d changed.
Molecular microbiologist Justin O’Sullivan says the comparisons showed that although the samples taken on successive days were very stable, only 45% of the original bacteria types remained decades later.
Certain genetic variants correlate with the presence or absence of particular species of gut bacteria. Because Apple has had his genome sequenced, the researchers were able to show that he had some types of bacteria but not others as a result of his genes.
O’Sullivan says the survival of nearly half the gut flora suggests that a selection process is at play, “otherwise, why would you keep it?”
“Instead of the microbiome simply being imposed on you, you select for some components of it, saying, ‘I need this bacterium but I don’t need that one.’”
Apple is listed as a co-author on a paper being submitted to medical journals, entitled, “The faecal microbiome of Billy Apple® 46 years apart.”
Says O’Sullivan: “Supplies of 46-year-old poo along with medical histories that are well documented and linked with that individual are non-existent.”