29 November 2001

Bacteroides fragilis: How gut flora hide

The cover shows B. fragilis expressing polysaccharide A (green), polysaccharide H (red) or both (yellow). (Photo: C. Krinos/E. Cahir-McFarland.)

The commensal microorganisms in the human gut are important to our well-being. Their metabolic capacity has been compared to that of the liver—much of it aiding digestion. The bugs themselves gain a cosy niche, if they can avoid clearance by the host. How they avoid immunosurveillance is unclear, but a study of surface variability reveals that the colonic organism Bacteroides fragilis presents a moving target, modulating surface antigenicity by producing a range of distinct capsular polysaccharides.

Extensive surface diversity of a commensal microorganism by multiple DNA inversions
CORINNA M. KRINOS, MICHAEL J. COYNE, KATJA G. WEINACHT, ARTHUR O. TZIANABOS, DENNIS L. KASPER & LAURIE E. COMSTOCK
Nature 414, 555-558 (29 November 2001)
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