Importance of Microbiomes in gut: how it clears bilirubin (Introduction)

by David Turell , Friday, February 16, 2024, 18:51 (72 days ago) @ David Turell

The bacteria in charge of the role:

https://www.the-scientist.com/humans-rely-on-gut-bacteria-for-an-enzyme-that-prevents-j...

"To find out if this gene encodes a bilirubin-digesting enzyme and not some other oxidoreductase, they transferred it into bacteria that couldn’t break down the pigment and measured whether these bugs developed bilirubin-busting abilities. They found that the gene conveyed the ability. Furthermore, these boosted bacteria broke down all four of bilirubin’s double bonds, indicating that additional bacterial enzymes aren’t needed for this step of bilirubin’s breakdown. “Previous microbiologists thought there might be four enzymes that were responsible for this,” said Hall. “But our enzyme is one enzyme that does four things.” The team named the enzyme bilirubin reductase (BilR).

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"Given the widespread expression of the gene in bacteria, the researchers turned their attention towards the human microbiome. They examined the gut bacterial genomes of 1,801 healthy adults and found that virtually all of them carried bilirubin-digesters. Hall said, “I’m amazed that this enzyme is present in essentially all adults—we said 99.9 percent. Even though the microbiome composition of adults is so different, there’s this commonality.”

"Healthy adults carry bilirubin-digesters, but the team wondered whether they were absent in people with certain illnesses. They found that more than 30 percent of people with inflammatory bowel disease and nearly 70 percent of infants under one month of age lacked bilirubin-digesters.5,6 Bacteria only begin to colonize the infant gut after birth, so the absence of bilirubin-digesters might partly explain why jaundice is common in newborns.7

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"BilR is just one of many gut bacterial enzymes that have evaded scientists. “There are a lot of unknown enzymes that are encoded by gut bacteria that play essential roles that are important for human physiology,” Jiang said, who aims to employ bioinformatic tools to dig up more of these hidden gems in the future. Hall added, “Understanding this dialogue between the host and the products from the microbiome is going to be critical to understanding how microbiomes contribute to health and disease.'”

Comment: bacteria were at life's origin and still around helping us.