Evolution of symbiotic bacteria in the distal human intestine.
The adult human intestine contains trillions of bacteria, representing hundreds of species and thousands of subspecies. Little is known about the selective pressures that have shaped and are shaping this community's component species, which are dominated by members of the Bacteroidetes and Firmicutes divisions. To examine how the intestinal environment affects microbial genome evolution, we have sequenced the genomes of two members of the normal distal human gut microbiota, Bacteroides vulgatus and Bacteroides distasonis, and by comparison with the few other sequenced gut and non-gut Bacteroidetes, analyzed their niche and habitat adaptations. The results show that lateral gene transfer, mobile elements, and gene amplification have played important roles in affecting the ability of gut-dwelling Bacteroidetes to vary their cell surface, sense their environment, and harvest nutrient resources present in the distal intestine. Our findings show that these processes have been a driving force in the adaptation of Bacteroidetes to the distal gut environment, and emphasize the importance of considering the evolution of humans from an additional perspective, namely the evolution of our microbiomes.
Xu
Jian
J
Center for Genome Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America.
Mahowald
Michael A
MA
Ley
Ruth E
RE
Lozupone
Catherine A
CA
Hamady
Micah
M
Martens
Eric C
EC
Henrissat
Bernard
B
Coutinho
Pedro M
PM
Minx
Patrick
P
Latreille
Philippe
P
Cordum
Holland
H
Van Brunt
Andrew
A
Kim
Kyung
K
Fulton
Robert S
RS
Fulton
Lucinda A
LA
Clifton
Sandra W
SW
Wilson
Richard K
RK
Knight
Robin D
RD
Gordon
Jeffrey I
JI
D000222:Adaptation, Physiological; D001435:Bacteriophages / Q000235:genetics; D001439:Bacteroides / Q000235:genetics* / Q000502:physiology / Q000821:virology; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements; D017753:Ecosystem; D019143:Evolution, Molecular; D020440:Gene Duplication; D022761:Gene Transfer, Horizontal; D014644:Genetic Variation; D016680:Genome, Bacterial; D006801:Humans; D007422:Intestines / Q000382:microbiology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis / Q000235:genetics; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013045:Species Specificity; D013559:Symbiosis / Q000235:genetics*
D004251:DNA Transposable Elements; D011135:Polysaccharides, Bacterial; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S