Advances in Microbial Ecology was established by the International Committee on Microbial Ecology (ICOME) to provide a vehicle for in-depth, critical, and even provocative reviews to emphasize recent trends in the important field of microbial ecology. Advances in Microbial Ecology is now recognized as a major source of infor mation and inspiration both for practicing and for prospective microbial ecologists. Most reviews appearing in Advances have been prepared by leaders in particular areas follow ing invitations issued by the Editorial Board. Individuals are encouraged, however, to submit outlines of unsolicited contributions to any member of the Editorial Board for consideration for publication in Advances. With the publication of Volume 12 of Advances in Microbial Ecology there will be a change of Editor and the entire Editorial Board. The current Editor wishes to take this opportunity to thank the present Editorial Board, Ron Atlas, Bo Barker J~rgensen, and Gwyn Jones, as well as past members of the Board, for their assistance and encourage ment over the years. The new Editor of Advances in Microbial Ecology will be Gwyn Jones, with Bernhard Schink, Warwick F. Vincent, and David M. Ward as members of the Editorial Board. The outgoing Board wish the new Board every success in continu ing the traditions established by Martin Alexander, the founding Editor of Advances in Microbial Ecology. The topics featured in Volume 12 of Advances include some related to the meta bolic activities of bacteria; namely, bioremediation of oil spills, by R. M. Atlas and R.