Microbiological study of the dripping waters in Altamira cave (Santillana del Mar, Spain).

The culturable microbial populations in dripping waters from Altamira cave were studied and compared with those of the ceiling rock. Water communities have low proportions of gram-positive bacteria, and are mainly composed of gram-negative rods and cocci (Enterobacteriaceae and Vibrionaceae), while those of ceiling rocks are mainly Streptomyces spp. The community differences are probably related to environmental cave conditions: high humidity, relatively low and stable temperature, water pH close to neutrality and nature of the organic matter. All these factors seem to favor colonization and long-term growth of actinomycetes over other heterotrophic bacteria on ceiling rocks.