1. M. I. Moré, J. L. Stryker, S. C. Winans, Section of Microbiology, Cornell University, Ithaca, NY 14853, USA.
2. L. D. Finger and A. Eberhard, Department of Chemistry, Ithaca College, Ithaca, NY 14850, USA.
3. C. Fuqua, Department of Biology, Trinity University, San Antonio, TX 78212, USA.