Bacterivory by a chrysophyte in slow sand filters

Weber‐Shirk, Monroe L.; Dick, Richard I.

doi:10.1016/s0043-1354(98)00272-3

Cited by 35 publications

(17 citation statements)

References 30 publications

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“…Similar significant correlations were found in the study of Marino and Gannon (1991) where comparisons of concentrations of bacteria and protozoan numbers in sediments gave an r 2 value of 0.6. Previous studies have confirmed the important role protozoa play in consuming bacteria in both sewage treatment and soil ecosystems (Acea and Alexander, 1988; Acea et al, 1988; Ayo et al, 2001; Decamp and Warren, 1998; Eberl et al, 1997; England et al, 1993; Griffiths, 1990), as well as a biological removal mechanism in slow sand filtration (Lloyd, 1996; Weber‐Shirk and Dick, 1997, 1999). It is, however, evident that other mechanisms such as adhesion of bacterial cells to filter media surface also play a role in bacterial removal as well as die‐off of bacterial cells in the system.…”

Section: Discussionmentioning

confidence: 82%

Bacterial Removal and Protozoan Grazing in Biological Sand Filters

Bomo¹,

Stevik²,

Hovi

et al. 2004

J of Env Quality

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The objective of the study was to investigate the importance of protozoan predation as a biological removal mechanism in sand filters used for purification of bacteria from wastewater. Eleven sand filter columns were seeded with a high dose of wastewater (70 mm d(-1)) and a high concentration (10(8) colony forming units [CFU] mL(-1)) of Aeromonas hydrophila (American Type Culture Collection [ATCC] 14715) for a period of 30 d. Water samples from three filter outlets were analyzed for the concentration of A. hydrophila. In addition, one filter column was sacrificed each sampling day for the quantification of A. hydrophila, culturable bacteria (heterotrophic plate counts, HPC), total bacterial counts, and protozoa in the sand. The mean removal efficiency of A. hydrophila in the sand filter columns was 4.7 log units. The concentration of A. hydrophila in the sand filter effluent, however, had a clearly time-dependent pattern from high (log 6) and unstable concentrations to low and more stable levels (log 2). The removal efficiency of A. hydrophila correlated significantly (P = 0.0005, r2 = 0.6) with numbers of protozoa in the sand filters. Significantly higher (P < 0.05) concentrations of A. hydrophila were observed in sand filter effluents from columns treated with the protozoan inhibitor cycloheximide, compared with nontreated columns. Results from the present study show that protozoan grazing plays an important role as a bacterial removal mechanism in sand infiltration systems.

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Section: Discussionmentioning

confidence: 82%

Bacterial Removal and Protozoan Grazing in Biological Sand Filters

Bomo¹,

Stevik²,

Hovi

et al. 2004

J of Env Quality

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“…Picture 1a-EPS fi lling the space between sand grains, 1b-bacteria, 2a-carbonate precipitation cementing the space between sand grain, 2b-bacteria, 3a-fungal hyphae, 3b-bacteria, 3c-calcite precipitation, 3d-fi ne EPS deposit, 4a-small bacterial cocci embedded in EPS, 4b-bacteria rod embedded in EPS, 4c-calcifi ed microorganisms, 4d-"nano spirulina", 5a-fi ne EPS fi lm, 5b-bacteria covered by fi ne EPS, 5c-carbonate precipitate, 6a-bacteria covered by a dense EPS accumulation, 7a-diatom skeleton, 8a-bacteria free of EPS, 8b-bacteria embedded in EPS. In column experiments, the addition of heterotrophic nanofl agellates or amoebae merely delayed the occurrence of clogging (DeLeo and Baveye, 1997;Weber-Shirk and Dick, 1999;Mattison et al, 2002), probably by grazing on attached bacteria. However, in our study, predator abundances were signifi cantly higher at the surface of C+ fi lters.…”

Section: Discussionmentioning

confidence: 94%

Influence of hydraulic conductivity on communities of microorganisms and invertebrates in porous media: a case study in drinking water slow sand filters

2006

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Abstract. The impact of reduced hydraulic conductivity on the abundance and diversity of microorganisms and invertebrates was examined in an artifi cial ecosystem consisting of a slow sand-fi lter. Sand-fi lters processed pre-treated lake water under high fl ow rates and acted as small ecosystems inhabited by a complex community. The fi rst trophic level consisting of microorganisms serves as a food source for a dense community of protists, micro-and macro-invertebrates. The reduction of hydraulic conductivity due to the development of larger bacterial and fungal biomass induced a shift of the microbial community towards anaerobiosis that may increase clogging by carbonate precipitation. The presence of more bacterial prey seems to favour the development of higher trophic levels. Predation and bioturbation by eukaryotes were not able to counteract the reduction of hydraulic conductivity due to prokaryotic clogging.

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“…Previous SSF studies have examined the ability of specific organisms (for example, Chrysophyte) to remove pathogenic bacteria (Weber-Shirk and Dick, 1999), or the overall pathogen removal efficiency of SSFs (Bomo et al, 2004, Grobe et al, 2006, Hijnen et al, 2007Elliott et al, 2008). However, these studies are limited by their specificity.…”

Section: Introductionmentioning

confidence: 99%

“…However, these studies are limited by their specificity. Further, on the basis of these studies, and knowledge from marine and terrestrial environments, both top-down (predation by protozoa and viral lysis) and bottom-up (nutrient/resource availability) mechanisms have been suggested as important for the regulation of microbial mortality (Lloyd, 1973;Hunter and Price, 1992;Pace and Cole, 1994;Weber-Shirk and Dick, 1999;Rosemond et al, 2001). In addition, theoretical models and empirical surveys have indicated that the majority of the mortality is due to grazing by protists, and to a lesser extent to viral lysis (Pernthaler, 2005).…”

Section: Introductionmentioning

confidence: 99%

Stable-isotope probing and metagenomics reveal predation by protozoa drives E. coli removal in slow sand filters

et al. 2014

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Stable-isotope probing and metagenomics were applied to study samples taken from laboratoryscale slow sand filters 0.5, 1, 2, 3 and 4 h after challenging with 13 C-labelled Escherichia coli to determine the mechanisms and organisms responsible for coliform removal. Before spiking, the filters had been continuously operated for 7 weeks using water from the River Kelvin, Glasgow as their influent source. Direct counts and quantitative PCR assays revealed a clear predator-prey response between protozoa and E. coli. The importance of top-down trophic-interactions was confirmed by metagenomic analysis, identifying several protozoan and viral species connected to E. coli attrition, with protozoan grazing responsible for the majority of the removal. In addition to top-down mechanisms, indirect mechanisms, such as algal reactive oxygen species-induced lysis, and mutualistic interactions between algae and fungi, were also associated with coliform removal. The findings significantly further our understanding of the processes and trophic interactions underpinning E. coli removal. This study provides an example for similar studies, and the opportunity to better understand, manage and enhance E. coli removal by allowing the creation of more complex trophic interaction models.

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Bacterivory by a chrysophyte in slow sand filters

Cited by 35 publications

References 30 publications

Bacterial Removal and Protozoan Grazing in Biological Sand Filters

Bacterial Removal and Protozoan Grazing in Biological Sand Filters

Influence of hydraulic conductivity on communities of microorganisms and invertebrates in porous media: a case study in drinking water slow sand filters

Stable-isotope probing and metagenomics reveal predation by protozoa drives E. coli removal in slow sand filters

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