Ethidium bromide-stained DGGE gel (negative image) showing the 194-bp PCR-amplified fragment of the 16S rRNA genes (V3 region) from the total bacterial communities from the SSF samples. Lane 1, reservoir; lane 2, storage tank; lanes 3 to 5, top layer of three replicate sand columns; lane 6, L. cherrii; lane 7, headwater; lane 8, outflow water; lane M, bacterial marker containing P. fluorescens (a), S. yanoikuyae (b), B. subtilis (c), B. phenazinium (d), P. amylolyticus (e), A. rhizogenes (f), and A. polychromogenes (g). The arrowhead indicates the DGGE band that was initially excised from the total bacterial community, cloned, and sequenced (homology to L. cherrii).