10 March 2000
Vol 287, Issue 5459

About The Cover

Cover image expansion

COVER Acid-tolerant slime streamers (biofilms) inhabit a subsurface tunnel at an unused copper mine in northern California; the stream shown here is about 1 meter wide. A previously unknown, iron-oxidizing Archaeon that is extremely acidophilic was found to dominate the microbial population within such biofilms, contributing to pyrite dissolution and the production of acid mine drainage. See page 1796 [Photo: K. J. Edwards]