Background: Child-care facilities appear to provide daily opportunities for exposure and transmission of bacteria and viruses. However, almost nothing is known about the diversity of microbial contamination in daycare facilities or its public health implications. Recent culture-independent molecular studies of bacterial diversity in indoor environments have revealed an astonishing diversity of microorganisms, including opportunistic pathogens and many uncultured bacteria. In this study, we used culture and culture-independent methods to determine the viability and diversity of bacteria in a child-care center over a six-month period.

In this study, we explored the possibility that dispersal from terrestrial subsurface sources 'seeds' the development of geothermal spring microbial assemblages. We combined microscopy and culture-independent molecular approaches to survey the bacterial diversity of spring source waters in Yellowstone National Park, Lassen Volcanic National Park, and Russia's Kamchatka peninsula. Microscopic analysis uncovered clear evidence of microbial cells from spring sources in all three regions. Analysis of source water phylogenetic diversity identified members of all bacteria groups found previously in downstream sediments, as well as many other phylogenetic groups. Closely related or identical 16S sequences were determined from the source waters of geographically distant, chemically distinct springs, and we found no association between spring water chemistry and microbial diversity. In the source waters of two different Yellowstone springs, we also discovered a phylogenetic group of uncultured Firmicutes never before reported in geothermal habitats that were closely related to uncultured bacteria found in the hyper-arid Atacama Desert. Altogether, our results suggest geothermal features can be connected via the subsurface over long distances and that subsurface sources provide a potentially diverse source of microorganisms for downstream surface mat communities.