Genetic Code Of SR1 Bacteria Cracked, Could Reveal Secrets About Life On Earth

Scientists cracked the genetic code of the bacteria that causes periodontitis, telling a story about what not only goes on in the recesses of the human mouth, but also on Earth itself.

The SR1 bacteria is a group of microbes that have never been cultivated in a laboratory but are found in many diverse environments including the human mouth, rivers, lakes and even termites.

Human oral SR1 bacteria are elevated in periodontitis, a disease marked by inflammation and infection of the ligaments and bones that support the teeth.

Scientists found that the SR1 bacteria employ a unique genetic code in which the codon UGA - a sequence of nucleotides guiding protein synthesis - appears not to serve its normal role as a stop code. In fact, scientists found that UGA serves to introduce a glycine amino acid instead, a release from Oak Ridge National Laboratory stated.

"This is like discovering that in a language you know well there is a dialect in which the word stop means go," said study co-author Mircea Podar in a statement.

The researchers believe the altered genetic code limits the exchange of genes between SR1 and other bacteria because they use a different genetic alphabet.

"In the big pool of bacteria, genes can be exchanged between species and can contribute to increased antibiotic resistance or better adaptation to living in humans," Podar said. "Because SR1 has a change in its genetic alphabet, its genes will not function in other microbes."

The finding will help forge a path towards better understanding of microbiological factors of periodontitis, as well as to help establish a framework that will enable scientists to interpret genomic data from the SR1 bacteria and others that have the same altered genetic code.

Podar noted that the SR1 bacteria was one of many bacteria found in the human mouth that little was known about. So far, no one has been able to isolate and cultivate the SR1 bacteria, but since the SR1's genetic code has been cracked, researchers may soon be able to reproduce the bacteria in a lab.

"The genetic information obtained by sequencing one single cell may offer researchers a key to 'domesticating' these organisms and studying them in the laboratory."