FIG. 5.

Phylogenetic affiliation of unattached (in groundwater) and attached (extracted from basalt) bacteria in fractured and packed columns by FISH using probes for gram positives (GmPos) with high G+C DNA content and α, β, and γ Proteobacteria. Counts are background corrected for nonspecific binding to NON338 and expressed as percentages of the total count hybridized to the Bacteria probe (EUB338) for each sample. Error bars indicate standard errors of independent replicate columns (except feed water—see below): unattached, packed, n = 4; attached, packed, n = 3; unattached, fractured, n = 4; attached, fractured, n = 5. Results obtained with the groundwater used as column feed, at the time of column sacrifice, are shown for comparison (four subsamples). The sum of percentages for a given sample type may not equal 100%, as averages of columns are presented and all counts were performed independently.