Twins can offer researchers an opportunity to study health and biology in people raised in the same environment with the same genes. Researchers wanted to know more about how stable and resilient microbes in the gut remain over time, and analyzed results from pairs of twins that had lived together for decades and started to live apart. Metagenomics methods can help scientists identify the microbial strains in a person's gut, and in this study, the investigators used databases from pairs of twins; one contained data from eight pairs of children that lived together and the other from 50 adult pairs between the ages of 36 and 80 who had periods of living apart ranging from one to 59 years.
"Adult twins, ages 36 to 80 years old, showed that a certain strain or strains between a pair of twins was shared post-separation," explained Casey Morrow, Ph.D., professor emeritus in the University of Alabama at Birmingham's Department of Cell, Developmental and Integrative Biology. "While we do not know the origin of these shared microbes in the twins, these results suggest the possibility of strains shared between non-cohabitating twins for decades. As a corollary to these studies, our studies establish a timeline for stability of microbial strains in the human gut."
The researchers used bioinformatics to generate a kind of microbial fingerprint that tracked the microbes they identified. They found that children that still lived together had significantly more bacterial strains in common, unsurprisingly. We know from other research that people who live together often have similar microbiomes. Adult twins that had not lived apart for more than ten years had many more strains in common compared to twins that had not lived together for more than ten years.
This study included 80-year-old twins that had only lived apart for one year, and they had the most strains in common. The other adults with the most strains in common were two pairs of twins, ages 56 and 73 that had not lived apart for more than five and seven years, respectively. In a few cases, they found strains that were still shared after twins had lived apart for decades.
"While certain gut microbial strains can be stable in people, in some cases for decades, changes in the host environmental conditions over time can impact the stability landscape of the gut microbial community," Morrow said. "This might result in the appearance of new strains that could potentially impact the microbial interactions that are essential for function in human health."