Ref ID : 1160
Margaret M. Roper and K.C. Marshall; Effects of a clay mineral on microbial predation and parasitism of Escherichia coli. Microbial Ecology 4:279-289, 1978
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Montmorillonitic clay influence the biological control of Escherichia coli in aquatic systems, the magnitude of the effects being dependent on the state of the clay and the type of host-antagonist interaction. The interaction of Bdellovibrio and E. coli was partially inhibited by the presence of montmorillonite. Because it is highly motile, Bdellovibrio apparently could penetrate any colloidal clay barrier around E. coli if the clay envelope was thin enough. Colloidal clay had little effect on predation of E. coli by the myxobacterium Polyangium, and had no effect on the activity of the amoeba Vexillifera. Crude clay, on the other hand, resulted in a physical separation of predator and prey, and this completely inhibited the E. coli-Polyangium interaction and slowed the rate of engulfment of E. coli by Vexillifera. The interference of natural biological control by clays may alter the microbial balance favoring survival of fecal microorganisms and resulting in their accumulation in saline sediments. This could constitute a health hazard if these organisms were released by upwelling of bottom waters or were desorbed in estuarine systems by dilution during heavy rains.