NEW YORK, March 28 - Two groups of researchers have sequenced the genomes of two bacteria that inhabit the human gut, Enterococcus faecalis and Bacteroides thetaiotaomicron.
Analyses of the genome sequences appear in two articles published in Science today.
Researchers led by The Institute for Genomic Research sequenced the genome of E. faecalis strain V583, the first vancomycin-resistant clinical isolate of the microbe reported in the US. They found that over a quarter of its genome consists of mobile or foreign DNA, possibly explaining why enterococci rapidly acquire and disseminate drug resistance. In total, the researchers identified 3337 predicted protein-encoding open reading frames on the bacterium's chromosome and three plasmids. E. faecalis is a major cause of urinary tract infections, bacteremia, and infective endocarditis, and its genome sequence "may facilitate the development of therapeutic approaches to combat this important nosocomial pathogen," the authors write.
B. thetaiotaomicron is a dominant member of the normal human gut. Scientists from Washington University School of Medicine in St. Louis found 4779 predicted protein-encoding genes in its genome, and assigned a putative function to about 60 percent of them. They found expanded groups of genes that are involved in taking up and breaking down polysaccharides, sensing the environment, mobilizing DNA, and producing capsule polysaccharides. "These expansions reveal strategies used by B. thetaiotaomicron to survive and dominate the densely populated intestinal ecosystem," the scientists write.