A detailed discussion of the influence of the amount of deposited polymer on the retention properties of polymer‐coated silicas

Hayrapetyan, Sergey S.; Khachatryan, H. G.; Neue, Uwe D.

doi:10.1002/jssc.200500408

Cited by 2 publications

(2 citation statements)

References 8 publications

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“…Previous experiments had shown that SSuT r E. coli exhibits a fitness advantage under both in vitro and in vivo conditions, but the underlying mechanism was not defined (11,12,16). To identify and characterize mechanisms responsible for these advantages, we conducted a series of pair-wise competition experiments using E. coli 25 against E. coli O157:H7 strain 1 as a target.…”

Section: Discussionmentioning

confidence: 99%

“…Neither antimicrobial drug use nor the presence of antimicrobial resistance genes was associated with the fitness trait observed in the multidrug-resistant E. coli in these animals (12,16). A fitness advantage could be shown by direct competition studies in vitro (16), and a clear advantage was evident when a milk supplement was included in the calf diet (11). The mechanism by which the fitness advantage was conferred has not been identified for either in vitro or in vivo cases.…”

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Proximity-Dependent Inhibition in Escherichia coli Isolates from Cattle

Sawant

Casavant

Call

et al. 2011

Appl Environ Microbiol

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We describe a novel proximity-dependent inhibition phenotype of Escherichia coli that is expressed when strains are cocultured in defined minimal media. When cocultures of "inhibitor" and "target" strains approached a transition between logarithmic and stationary growth, target strain populations rapidly declined >4 log CFU per ml over a 2-h period. Inhibited strains were not affected by exposure to conditioned media from inhibitor and target strain cocultures or when the inhibitor and target strains were incubated in shared media but physically separated by a 0.4-m-pore-size membrane. There was no evidence of lytic phage or extracellular bacteriocin involvement, unless the latter was only present at effective concentrations within immediate proximity of the inhibited cells. The inhibitory activity observed in this study was effective against a diversity of E. coli strains, including enterohemorrhagic E. coli serotype O157:H7, enterotoxigenic E. coli expressing F5 (K99) and F4 (K88) fimbriae, multidrug-resistant E. coli, and commensal E. coli. The decline in counts of target strains in coculture averaged 4.8 log CFU/ml (95% confidence interval, 4.0 to 5.5) compared to their monoculture counts. Coculture of two inhibitor strains showed mutual immunity to inhibition. These results suggest that proximity-dependent inhibition can be used by bacteria to gain a numerical advantage when populations are entering stationary phase, thus setting the stage for a competitive advantage when growth conditions improve.With the discovery of quorum sensing in the 1960s and 1970s, in comparison to the discovery of colicins in the 1920s, it became evident that populations of individual cells are capable of coordinating functions by using signaling molecules for communication. These communications can enhance fitness in a multispecies community, help exploit nutrients more efficiently, increase cooperation with neighboring cells, or harm competing bacteria. Some of the cell-to-cell communications have been well characterized. Streptococcus oralis 34 secretes an autoinducer that signals Actinomyces naeslundii T14V to congregate with S. oralis 34 and form a mutualistic biofilm in saliva (21). Vibrio cholerae uses autoinducers to shut down expression of virulence factors and biofilm formation at high cell densities (13). As an SOS response, certain bacteria can produce toxins, called bacteriocins, which can kill a narrow spectrum of competing cells that express suitable cell surface receptors (8)(9)(10)14). Bacteria can also produce inhibitory phage particles and iron-sequestering aerobactin to gain an advantage over competing bacteria (6,23).Many of these mechanisms enhance the fitness of bacterial strains in a given environment. Khachatryan et al. in 2004 observed a fitness trait allowing certain multidrug-resistant Escherichia coli in Holstein calves to dominate the enteric E. coli population (16). Neither antimicrobial drug use nor the presence of antimicrobial resistance genes was associated with the fitness trait observed in the ...

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Section: Discussionmentioning

confidence: 99%

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confidence: 90%