Laboratory growth rates of six species of freshwater Gymnamoebia

Baldock, B. M.; Baker, J. H.; Sleigh, M. A.

doi:10.1007/bf00346813

Cited by 34 publications

(20 citation statements)

References 18 publications

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“…The concentration of L. pneumophila increased exponentially after the first H. vermiformis protozoa were detected. The growth rates of H. vermiformis obtained in this study were 2.9-fold higher than the maximum growth rates of naked amoebae in their natural environment (3) and were similar to the highest growth rates of naked amoebae obtained under laboratory conditions (4,8). Hence, the aquatic biofilm developing on the pieces of PVCp provided a favorable environment for the growth of H. vermiformis.…”

supporting

confidence: 69%

Intracellular Proliferation of Legionella pneumophila in Hartmannella vermiformis in Aquatic Biofilms Grown on Plasticized Polyvinyl Chloride

Kuiper

Wullings

Akkermans

et al. 2004

Appl Environ Microbiol

114

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The need for protozoa for the proliferation of Legionella pneumophila in aquatic habitats is still not fully understood and is even questioned by some investigators. This study shows the in vivo growth of L. pneumophila in protozoa in aquatic biofilms developing at high concentrations on plasticized polyvinyl chloride in a batch system with autoclaved tap water. The inoculum, a mixed microbial community including indigenous L. pneumophila originating from a tap water system, was added in an unfiltered as well as filtered (cellulose nitrate, 3.0-m pore size) state. Both the attached and suspended biomasses were examined for their total amounts of ATP, for culturable L. pneumophila, and for their concentrations of protozoa. L. pneumophila grew to high numbers (6.3 log CFU/cm 2 ) only in flasks with an unfiltered inoculum. Filtration obviously removed the growth-supporting factor, but it did not affect biofilm formation, as determined by measuring ATP. Cultivation, direct counting, and 18S ribosomal DNA-targeted PCR with subsequent sequencing revealed the presence of Hartmannella vermiformis in all flasks in which L. pneumophila multiplied and also when cycloheximide had been added. Fluorescent in situ hybridization clearly demonstrated the intracellular growth of L. pneumophila in trophozoites of H. vermiformis, with 25.9% ؎ 10.5% of the trophozoites containing L. pneumophila on day 10 and >90% containing L. pneumophila on day 14. Calculations confirmed that intracellular growth was most likely the only way for L. pneumophila to proliferate within the biofilm. Higher biofilm concentrations, measured as amounts of ATP, gave higher L. pneumophila concentrations, and therefore the growth of L. pneumophila within engineered water systems can be limited by controlling biofilm formation.Legionella pneumophila is widespread in natural freshwater environments, despite its fastidious nature (16). The bacterium has also frequently been observed in engineered water systems such as warm water distributing systems, cooling towers, humidifiers, and fountains (25,43,50). The multiplication of the organism in water systems poses a potential human health risk when aerosolization can occur (12).Legionellae grow in vitro only in complex media with supplements of cysteine and iron salts (11). For their multiplication in vivo, other microorganisms are required, but different species of heterotrophic bacteria (Pseudomonas aeruginosa, Klebsiella pneumoniae, and Flavobacterium sp.) alone do not support the growth of L. pneumophila (31,45). In vitro studies using cocultures have repeatedly demonstrated the intracellular multiplication of L. pneumophila in amoebae (Acanthamoeba, Echinamoeba, Hartmannella, Naegleria, Vahlkampfia, and Dictyostelium) and in a ciliated protozoon (Tetrahymena pyriformis) (12,15,21,39). Amoebae have been observed in water systems associated with Legionnaires' disease (5, 7), and L. pneumophila can recolonize water distributing systems within a few weeks after disinfection (26,27). Batch experiments with tap wate...

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supporting

confidence: 69%

Intracellular Proliferation of Legionella pneumophila in Hartmannella vermiformis in Aquatic Biofilms Grown on Plasticized Polyvinyl Chloride

Kuiper

Wullings

Akkermans

et al. 2004

Appl Environ Microbiol

114

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“…Published specific growth rates and ingestion rates of amoebae determined with agar‐based experimental systems are rare, and data are highly variable. Ingestion rates range from 0.2 to 1465 bacteria per amoeba per hour at 20°C (Rogerson et al , 1996; Butler & Rogerson, 1997; Mayes et al , 1997; Heaton et al , 2001), whereas those for specific growth rate range from 0.01 to 0.15 h −1 at 20°C (Baldock & Baker, 1980; Baldock et al , 1980; Laybourn & Whymant, 1980). Calculated growth rates and ingestion rates in the present study (Table 1) fall within the published range, but a direct comparison of parameters between experiments is difficult, because other authors employed different amoeba species, heat‐killed fluorescently labelled prey, and a direct method for determining ingestion rate (fluorescent prey per amoeba over time).…”

Section: Resultsmentioning

confidence: 99%

A comparison of the growth and starvation responses of Acanthamoeba castellanii and Hartmannella vermiformis in the presence of suspended and attached Escherichia coli K12

Pickup

Parry

2007

FEMS Microbiology Ecology

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The growth and starvation responses of Acanthamoeba castellanii and Hartmannella vermiformis were investigated in the presence and absence of Escherichia coli on an agar surface or within shaken suspensions. The amoebae perceived all the suspended systems to be unfavourable for growth, despite being challenged with high levels of prey, and as a consequence they exhibited a starvation response. However, the response differed between species, with A. castellanii producing characteristic cysts and H. vermiformis producing round bodies. These amoebic forms were reactivated into feeding trophozoites in the presence of bacterial aggregates, which formed in the suspended systems after 68 h of incubation. In contrast, both species of amoebae grew well in the presence of attached E. coli at a concentration of 1 x 10(6) cells cm(-2) of agar and yielded specific growth rates of c. 0.04 h(-1). Starvation responses were induced at the end of the growth phase, and these were equivalent to those recorded in the suspended systems. We conclude that, when suspended, amoebae in the 'floating form' cannot feed effectively on suspended prey, and hence the starvation response is initiated. Thus the majority of amoebic feeding is via trophozoite grazing of attached bacterial prey.

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“…2). However, temperature appears to have little effect on the scaling of growth rate in ciliates (Finlay 1977) and amoebae (Baldock et al. 1980).…”

Section: Discussionmentioning

confidence: 99%

Metabolic level and size scaling of rates of respiration and growth in unicellular organisms

Glazier¹

2009

Functional Ecology

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Summary1. Metabolic rate is conventionally assumed to scale with body mass to the 3 ⁄ 4-power, independently of the metabolic level of the organisms being considered. However, recent analyses in a variety of animals and plants indicate that the power (log-log slope) of this relationship varies significantly with metabolic level, ranging from c. 2 ⁄ 3 to 1. 2. Here I show that the scaling slopes of rates of respiration and growth are related to the metabolic level of a variety of unicellular organisms, as similarly occurs for respiration rates in multicellular organisms. 3. The recently proposed 'metabolic-level boundaries hypothesis' provides insight into these effects of metabolic level. As predicted, the scaling slopes for resting (endogenous) respiration rate in prokaryotes, algae and protozoans are negatively related to metabolic level; and in protozoans, the scaling slope increases with starvation. Also as predicted, the scaling slopes of growth rate in algae and protozoans are negatively related to growth level. Unexpectedly, opposite effects of starvation on the metabolic scaling slopes of unicellular prokaryotes (compared to that of eukaryotes) may be a spurious result of respiration measurements that did not adequately consider the effects of rapid cell multiplication in prokaryotes with extremely short generation times. 4. Analyses of both unicellular and multicellular organisms show that there is no universal metabolic scaling relationship, and that variation in metabolic scaling relationships is systematically and possibly universally related to metabolic level.

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Laboratory growth rates of six species of freshwater Gymnamoebia

Cited by 34 publications

References 18 publications

Intracellular Proliferation of Legionella pneumophila in Hartmannella vermiformis in Aquatic Biofilms Grown on Plasticized Polyvinyl Chloride

Intracellular Proliferation of Legionella pneumophila in Hartmannella vermiformis in Aquatic Biofilms Grown on Plasticized Polyvinyl Chloride

A comparison of the growth and starvation responses of Acanthamoeba castellanii and Hartmannella vermiformis in the presence of suspended and attached Escherichia coli K12

Metabolic level and size scaling of rates of respiration and growth in unicellular organisms

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