Journal of Cave and Karst Studies - ISSN 1090-6924
Volume 62 Number 2: 80-90 - August 2000

A publication of the National Speleological Society

Evidence for geomicrobiological interactions in Guadalupe caves
Diana E. Northup, Clifford N. Dahm, Leslie A. Melim, Michael N. Spilde, Laura J. Crossey, Kathy H. Lavoie, Lawrence M. Mallory, Penelope J. Boston, Kimberley I. Cunningham and Susan M. Barns

Abstract

Caves in the Guadalupe Mountains offer intriguing examples of possible past or present geomicrobiological interactions within features such as corrosion residues, pool fingers, webulites, u-loops, and moonmilk. Scanning electron microscopy, transmission electron microscopy, molecular biology techniques, enrichment cultures, bulk chemistry, and X-ray diffraction techniques have revealed the presence of iron- and manganese-oxidizing bacteria in corrosion residues, which supports the hypothesis that these organisms utilize reduced iron and manganese from the limestone, leaving behind oxidized iron and manganese. Metabolically active populations of bacteria are also found in “punk rock” beneath the corrosion residues. Microscopic examination of pool fingers demonstrates that microorganisms can be inadvertently caught and buried in pool fingers, or can be more active participants in their formation. Enrichment cultures of moonmilk demonstrate the presence of a variety of microorganisms. Humans can have a deleterious impact on microbial communities in Guadalupe caves.

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