Inactivation of a single gene enables microaerobic growth of the obligate anaerobe Bacteroides fragilis.
Bacteroides fragilis can replicate in atmospheres containing ≤0.05% oxygen, but higher concentrations arrest growth by an unknown mechanism. Here we show that inactivation of a single gene, oxe (i.e., oxygen enabled) in B. fragilis allows for growth in concentrations as high as 2% oxygen while increasing the tolerance of this organism to room air. Known components of the oxidative stress response including the ahpC, kat, batA-E, and tpx genes were not individually important for microaerobic growth. However, a Δoxe strain scavenged H(2)O(2) at a faster rate than WT, indicating that reactive oxygen species may play a critical role in limiting growth of this organism to low-oxygen environments. Clinical isolates of B. fragilis displayed a greater capacity for growth under microaerobic conditions than fecal isolates, with some encoding polymorphisms in oxe. Additionally, isolation of oxygen-enabled mutants of Bacteroides thetaiotaomicron suggests that Oxe may mediate growth arrest of other anaerobes in oxygenated environments.
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA.
Brian M
BM
Meehan
Anthony D
AD
Baughn
Rene
R
Gallegos
Michael H
MH
Malamy
D000693:Anaerobiosis; D001441:Bacteroides fragilis / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D020868:Gene Silencing; D005798:Genes, Bacterial / Q000235:genetics*; D006861:Hydrogen Peroxide / Q000378:metabolism; D018384:Oxidative Stress / Q000235:genetics*; D010100:Oxygen / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D017382:Reactive Oxygen Species; D017422:Sequence Analysis, DNA; D013045:Species Specificity
D017931:DNA Primers; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D010100:Oxygen