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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, Zoë L and Pickup, Roger and Parry, Jacqueline D (2007) A comparison of the growth and starvation responses of Acanthamoeba castellanii and Hartmannella vermiformis in the presence of suspended and attached Escherichia coli K12. FEMS Microbiology Ecology, 59 (3). pp. 556-563. ISSN 0168-6496

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Abstract

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.

Item Type: Article
Journal or Publication Title: FEMS Microbiology Ecology
Uncontrolled Keywords: amoeba ; cyst ; yield ; growth ratE ; ingestion rate ; biofilm
Subjects: Q Science > QH Natural history > QH301 Biology
Departments: Faculty of Health and Medicine > Biomedical & Life Sciences
Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 60192
Deposited By: ep_importer_pure
Deposited On: 22 Nov 2012 14:09
Refereed?: Yes
Published?: Published
Last Modified: 22 Nov 2012 14:09
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/60192

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