Effect of mineral composition on bacterial attachment to submerged rock surfaces

A direct microscopic count technique employing fluorescein isothiocyanate stain was used to compare microbial colonization on the exposed surfaces of rocks and minerals suspended in several ponds for various time intervals. Hematitic sandstone was never colonized at a rate greater than limestone, but quartz was always colonized more rapidly than calcite. The use of single-crystal minerals (quartz and calcite) in a nested factor experiment showed that the effect of the minerals on colonization was statistically significant, but that differences among the immersion sites were also significant. Sandstone samples placed in a pond outflow accumulated microbial colonizers more rapidly than those placed in the still waters of the same pond. The results indicate that the composition of the mineral substrate, in concert with the immersion environment, controls the formation of primary slime layers in aquatic systems.