Biology Reference
In-Depth Information
Abstract
Bacteria properties play an important role in the transport of bacteria in groundwater, but their
role, especially for longer transport distances (> 0.5 m) has not been studied. Thereto, we studied
the effects of cell surface hydrophobicity, outer surface potential, cell sphericity, motility, and
Ag43 protein expression on the outer cell surface for a number of
E. coli
strains, obtained from
the environment on their transport behavior in columns of saturated quartz sand of 5 m height in
two solutions: demineralized water (DI) and artificial groundwater (AGW). In DI, sticking
efficiencies ranged between 0.1-0.4 at the column inlet, and then decreased with transport
distance to 0.02-0.2. In AGW, sticking efficiencies were on average 1 log unit higher than those
in DI. Bacteria motility and Ag43 expression affected attachment with a (high) statistical
significance. In contrast, hydrophobicity, outer surface potential and cell sphericity did not
significantly correlate with sticking efficiency. However, for transport distances more than 0.33
m, the correlation between sticking efficiency, Ag43 expression, and motility became
insignificant. We concluded that Ag43 and motility played an important role in E. coli
attachment to quartz grain surfaces, and that the transport distance dependent sticking efficiency
reductions were caused by motility and Ag43 expression variations within a population. The
implication of our findings is that less motile bacteria with little or no Ag43 expression may
travel longer distances once they enter groundwater environments. In future studies, the possible
effect of bacteria surface structures, like fimbriae, pili and surface proteins on bacteria
attachment need to be considered more systematically in order to arrive at more meaningful
inter-population comparisons of the transport behavior of
E. coli
strains in aquifers.
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