Nitrogen Metabolizing Enzyme Activities In the Free‐Living Soil Amoebae Acanthamoeba Castellanii, Acanthamoeba Polyphaga and Hartmannella Vermiformis

Weekers, Peter H. H.; Drift, Chris van der

doi:10.1111/j.1550-7408.1993.tb04912.x

Cited by 41 publications

(52 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The 20 significant protozoan species represented 15 different genera and members from the flagellate, ciliate and amoeboid groups, all of which are known predators of E. coli (Weekers et al, 1993;Fleck et al, 2000;Fey et al, 2007;Cassidy-Hanley, 2012;Yue et al, 2013). Referring to Figure 4c, it can be seen that the proportion of significant protozoan species in 13 C samples increased over time, compared with Figure 2 Absolute numbers of 16S, 18S and E. coli specific 16S rRNA in 12 C and 13 C fractions, determined by qPCR assays.…”

Section: Resultsmentioning

confidence: 92%

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

et al. 2014

View full text Add to dashboard Cite

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.

show abstract

Section: Resultsmentioning

confidence: 92%

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

et al. 2014

View full text Add to dashboard Cite

show abstract

“…However, the former explanation seems likely since, by day 7, there was a larger proportion of Ap and Ac30234 ATs (actively feeding form) during incubation with LVS than Ac30010 and Vv cells, where microscopy images showed mostly rounded trophozoites/pre-cysts and cysts (C, dormant form) ( Figure 6 and Supplementary Figure 1). With various Gram-positive and Gram-negative bacteria that are commonly found in soil and water as the sole food source, Ap, Ac, and Vv cells exhibited an increased growth and ammonium production rate, in that order, indicating select Ap and Ac strains are more adept at utilizing bacteria as a food source than Vv [37]. However, the ability to degrade microbial cell wall components, or bacteriolytic activity, of Vv culture lysates were greater than Ac and Ap cultures when evaluating lysis of similar environmental Gram-negative and Gram-positive bacteria [38], indicating that the feeding behavior assessment of FLA may be assay and strain dependent.…”

Section: Discussionmentioning

confidence: 99%

Enhanced survival but not amplification of Francisella spp. in the presence of free-living amoebae

Buse

Schaefer

Rice

2016

Acta Microbiologica et Immunologica Hungarica

View full text Add to dashboard Cite

Transmission of Francisella tularensis, the etiologic agent of tularemia, has been associated with various water sources. Survival of many waterborne pathogens within free-living amoeba (FLA) is well documented; however, the role of amoebae in the environmental persistence of F. tularensis is unclear. In this study, axenic FLA cultures of Acanthamoeba castellanii, Acanthamoeba polyphaga, and Vermamoeba vermiformis were each inoculated with virulent strains of F. tularensis (Types A and B), the attenuated live vaccine strain, and Francisella novicida. Experimental parameters included low and high multiplicity of infection and incubation temperatures of 25 and 30°C for 0-10 days. Francisella spp. survival was enhanced by the presence of FLA; however, bacterial growth and protozoa infectivity were not observed. In contrast, coinfections of A. polyphaga and Legionella pneumophila, used as an amoeba pathogen control, resulted in bacterial proliferation, cytopathic effects, and amoebal lysis. Collectively, even though short-term incubation with FLA was beneficial, the long-term effects on Francisella survival are unknown, especially given the expenditure of available amoebal derived nutrients and the fastidious nature of Francisella spp. These factors have clear implications for the role of FLA in Francisella environmental persistence.

show abstract

“…This difference may in part be explained by the higher yield of H. vermiformis than Acanthamoeba spp. when feeding on prey bacteria (58).…”

Section: Discussionmentioning

confidence: 99%

Relationships between Free-Living Protozoa, Cultivable Legionella spp., and Water Quality Characteristics in Three Drinking Water Supplies in the Caribbean

Valster

Wullings

Berg

et al. 2011

Appl Environ Microbiol

View full text Add to dashboard Cite

The study whose results are presented here aimed at identifying free-living protozoa (FLP) and conditions favoring the growth of these organisms and cultivable Legionella spp. in drinking water supplies in a tropical region. Treated and distributed water (؎30°C) of the water supplies of three Caribbean islands were sampled and investigated with molecular techniques, based on the 18S rRNA gene. The protozoan host Hartmannella vermiformis and cultivable Legionella pneumophila were observed in all three supplies. Operational taxonomic units (OTUs) with the highest similarity to the potential or candidate hosts Acanthamoeba spp., Echinamoeba exundans, E. thermarum, and an Neoparamoeba sp. were detected as well. In total, 59 OTUs of FLP were identified. The estimated protozoan richness did not differ significantly between the three supplies. In supply CA-1, the concentration of H. vermiformis correlated with the concentration of Legionella spp. and clones related to Amoebozoa predominated (82%) in the protozoan community. These observations, the low turbidity In tropical regions, the water temperature in drinking water distribution system is permanently about 30°C (4). In these regions, free-living protozoa (FLP), serving as hosts for pathogenic bacteria, including Acanthamoeba spp. (1, 38), Hartmannella spp. (37), and Naegleria spp. (38, 49), have been observed in surface water, wastewater, cooling towers, and drinking water (3,5,19,45). Certain FLP with pathogenic properties, viz. Acanthamoeba spp. (9, 21), Balamuthia mandrillaris (54), and Naegleria fowleri (59), can proliferate in drinking water-related biofilms at elevated temperatures (36). In addition, Legionella pneumophila, the main etiologic agent of Legionnaires' disease (12), which proliferates in freshwater at temperatures above 25°C (57), is frequently observed in these environments (14,31,39).FLP in aquatic environments feed on bacteria, fungi, other protozoa, and organic detritus in biofilms and sediments or in the planktonic phase (32). The abundance of prey organisms and detritus depends on the water composition and the hydraulic conditions in distribution systems, which therefore also affect both the FLP abundance and community composition (52, 55). Most information on community composition and abundance of FLP in freshwater environments has been obtained by using cultivation methods and microscopy. Recently, however, the presence and identities of such organisms in drinking water supplies in temperate regions have been studied by using molecular methods for detection and identification (33, 51). In two groundwater supplies in the Netherlands a total of 127 operational taxonomic units (OTUs) of FLP were identified based on their 18S rRNA gene sequences. FLP, mostly pathogens, have been characterized in only a few studies in tropical regions (3,5,19). In recent reviews it was concluded that more research is needed to determine which factors favor the growth of these organisms in water supplies (47,48).Cases of Legionnaires' disease have been reporte...

show abstract

Nitrogen Metabolizing Enzyme Activities In the Free‐Living Soil Amoebae Acanthamoeba Castellanii, Acanthamoeba Polyphaga and Hartmannella Vermiformis

Cited by 41 publications

References 25 publications

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

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

Enhanced survival but not amplification of Francisella spp. in the presence of free-living amoebae

Relationships between Free-Living Protozoa, Cultivable Legionella spp., and Water Quality Characteristics in Three Drinking Water Supplies in the Caribbean

Contact Info

Product

Resources

About