If the seaweeds nori, kombu, or wakame have lengthy been a part of your weight loss program, there’s probability your intestine micro organism harbor genes from sea life. Microbiologists have found the human intestine microbiome has acquired this unique DNA a number of occasions throughout the historical past of seaweed consumption in Asia.
Whether these genes will be acquired in a matter of months or 1000’s of years continues to be an open query. Regardless, the phenomenon “may help us better understand the origin of [the] many novel genes in the human microbiome,” says Arshan Nasir, a bioinformatician at Moderna involved in microbial evolution.
The human intestine hosts 1000’s of microbial species—principally micro organism and viruses—of which the micro organism collectively comprise about 500,000 genes. Researchers solely know what half of these do. Some break complicated carbohydrates (equivalent to these present in grains and a few greens) into energy-rich molecules referred to as fatty acids that the human physique can take in and use. However, these genes can’t break down the complicated carbohydrates in seaweed and different marine algae. Could marine organisms have given us a hand in getting vitamins from seaweed?
The first clues that they may took place 10 years in the past. Researchers discovered a cluster of seaweed-digesting genes from a marine bacterium that eats nori in human intestine microbes. To learn the way widespread these genes had been in folks, Eric Martens, a microbiologist on the University of Michigan, Ann Arbor, and his colleagues positioned human fecal samples on plates containing seaweed extracts. They then analyzed the genomes of the micro organism that survived on the extracts, reasoning that these microbes had been those that might digest seaweed.
Some micro organism had the identical nori-digesting genes discovered earlier, whereas others had completely different genes with the identical functionality, the crew stories immediately in Cell Host & Microbe. Most of the microbes had been Bacteroidetes, a extremely numerous group that’s among the many commonest kinds of micro organism within the intestine, soil, and fresh- and saltwater. The genes within the human intestine microbes clustered collectively in cellular packets of DNA, suggesting they possible got here from marine Bacteroidetes utilizing a course of referred to as horizontal gene switch. People consuming seaweed or different sea life might need ingested these micro organism.
The crew additionally discovered one other set of seaweed-digesting genes in a special group of widespread intestine micro organism, Firmicutes. Because of similarities between these genes and genes in DNA databases, the researchers say these genes might have come from a bacterium discovered within the guts of fish that individuals ate. “I’m willing to bet that if we kept on searching, we’d find more [transfer] events,” Martens says.
Next, his postdoc Gabriel Pereira seemed for the seaweed-digesting genes within the guts of almost 2500 folks from North and South America, Africa, Europe, and Asia. The researchers discovered genes for digesting nori in 512 of the 1361 samples from Japanese and Chinese contributors, however in only a few contributors from elsewhere. Those Asian contributors had been additionally extra prone to have the genes wanted to digest different kinds of seaweed.
That is smart as a result of Asian cultures have lengthy consumed seaweed, says Justin Sonnenburg, a microbiologist at Stanford University who was not concerned with the examine. The proven fact that the genes have caught round in these folks suggests they play an necessary function in serving to digest the fiber within the algae, he says.
Martens can’t inform when these genes had been acquired by both the Bacteroidetes or the Firmicutes within the intestine. He and others suspect it might be a whole bunch and even 1000’s of years in the past. But it might additionally take simply months of a daily seaweed weight loss program, particularly if folks dwell amongst others who usually eat these meals. (The microbiomes of people that dwell collectively are likely to turn into extra comparable over time.)
This pure experiment might be harnessed for human well being, says Nasir, who was not a part of the analysis. Novome Biotechnologies, for instance, has endowed a seaweed-digesting bacterium with the flexibility to degrade dietary oxalate, a compound that may result in kidney stones. In ongoing scientific trials, folks in danger for kidney stones take this modified bacterium as a probiotic and guarantee it thrives within the intestine by additionally consuming seaweed dietary supplements. If for some motive, they should do away with this bacterium, they’ll merely cease taking the seaweed complement.
Even if this biomedical utility doesn’t pan out, horizontal gene switch has been good for folks, Martens says. Humans “do not have to evolve these functions,” he says. They can merely purchase new ones from micro organism.