Effects of Bacterial Prey Species and Their Concentration on Growth of the Amoebae Acanthamoeba castellanii and Hartmannella vermiformis

Abstract

Two amoebae were presented with six bacterial prey at a range of concentrations, and the growth parameters of the amoebae were deduced. All but one bacterium (Synechococcus) resulted in a positive growth response, but the gram-positive bacterium Staphylococcus aureus proved to be difficult to digest and the heavily pigmented bacterium Klebsiella ozaenae induced unusual amoebic behavior prior to ingestion.Protozoa are the major predators in microbial food webs (2), but the effects of different groups vary depending on the specific habitat. In biofilms, amoebae are considered more important than flagellates and ciliates due to their obligatory surface-associated lifestyle (20), but quantitative studies of amoeba-bacterium interactions are rare. Although in some studies workers have obtained amoebic growth parameters (3,7,17), in very few studies have workers examined the effect of bacterial prey type (28) or concentration (4) on amoebic growth. In this study we addressed this paucity of information by examining the interaction between two amoebae and six bacterial prey at different concentrations.

Risk Assessment for the Spread of Serratia marcescens Within Dental-Unit Waterline Systems Using Vermamoeba vermiformis

“…This is in agreement with the description of an ideal food source for amoebae suggested by Pickup et al [39] i.e ease of intake during phagocytosis/ingestion. Since amoebae appear to be genetically programmed to eat bacteria it is plausible to suggest that V. vermiformis, may be able to control bacterial populations by feeding on newly dividing S. marcescens providing a promising outcome for infection control in dental treatment.…”

“…However, in this investigation, V. vermiformis also fed on P. aeruginosa (p < 0.05). These results strongly agree with the study conducted by Pickup et al [39], but disagrees with those of Groscop & Brent [19] who suggested that P. aeruginosa was toxic to an unknown species of the genus Hartmannella.…”

“…Once inside the amoebal cell, some bacteria will survive or escape the adverse conditions presented by digestive vacuoles, but can also find sanctuary from unfavourable environmental conditions and can multiply [25]. Furthermore, bacteria such as S. aureus may be ingested, but released undigested and intact [39]. This implies that amoebae can transport certain species of nosocomial bacteria within their ecological niches [56].…”

Digestion of bacteria by the freshwater ciliate Tetrahymena pyriformis

“…However, this predator-prey relationship is complex as some bacteria can prevent normal digestive processes within protozoan food vacuoles (Abu Kwaik et al 1998, Strahl et al 2001, whilst others can undergo the full digestive process and emerge apparently unharmed (Schlimme et al 1995, Pickup et al 2007, Dillon & Parry 2009). This latter phenomenon is poorly understood and may be a result of an active response by bacteria, as it is for pathogens (Abu Kwaik et al 1998), or selective or inefficient digestion by protozoa (González et al 1990).…”

Eukaryotic Biodiversity in Mixed Peat Ecosystems in Sarawak, Malaysia

“…Hartmannella, an amoeba predators in Figure 5d. Phylogeny of eukaryotic phyla under 11 years oil palm at Naman Park Sibu, Sarawak, Malaysia. microbial food webs (Pickup et al, 2007) was found in oil palm plantations.…”