Wu, Qinglong L.; Boenigk, Jens; Hahn, Martin W.:
Successful predation of filamentous bacteria by a nanoflagellate challenges current models of flagellate bacterivory
2004
In: Applied and Environmental Microbiology, Jg. 70 (2004), Heft 1, S. 332 - 339
Artikel/Aufsatz in Zeitschrift / Fach: Biologie
Fakultät für Biologie » Allgemeine Botanik
Titel:
Successful predation of filamentous bacteria by a nanoflagellate challenges current models of flagellate bacterivory
Autor(in):
Wu, Qinglong L.; Boenigk, Jens im Online-Personal- und -Vorlesungsverzeichnis LSF anzeigen; Hahn, Martin W.
Erscheinungsjahr:
2004
Erschienen in:
Applied and Environmental Microbiology, Jg. 70 (2004), Heft 1, S. 332 - 339
ISSN:
Signatur der UB:
Link URL:

Abstract:

Current models suggest that (i) filamentous bacteria are protected against predation by nanoflagellates, (ii) prey size is positively correlated with prey-predator contact probability, and (iii) contact probability is mainly responsible for size-selective predation by interception-feeding flagellates. We used five strains of filamentous bacteria and one bacterivorous nanoflagellate, Ochromonas sp. strain DS, to test these assumptions. The five strains, including one spirochete and four Betaproteobacteria strains, were isolated by the filtration-acclimatization method. All five strains possess flexible cells, but they differ in average cell length, which ranged from 4.5 to 13.7 mum. High-resolution video microscopy was used to measure contact, capture, and ingestion rates, as well as selectivity of the flagellate feeding. Growth and feeding experiments with satiating and nonsatiating food conditions, as well as experiments including alternative well-edible prey, were performed. In contrast to predictions by current models, the flagellate successfully consumed all the tested filamentous strains. The ingestion rate was negatively correlated with bacterial length. On the other hand, the lengths of the filamentous bacteria were not positively correlated to the contact rate and capture rate but were negatively correlated to ingestion efficiency. In experiments including alternative nonfilamentous prey, the flagellates showed negative selection for filamentous bacteria, which was independent of food concentration and is interpreted as a passive selection. Our observations indicate that (i) size alone is not sufficient to define a refuge for filamentous bacteria from nanoflagellate predation and (ii) for the investigated filamentous bacteria, prey-predator contact probability could be more influenced by factors other than the prey size.