Potential of galvanotaxis to separation and cleaning of rumen ciliates Svetlana Kis ˇidayova ´ * , Zora Va ´radyova ´ Institute of Animal Physiology, Slovak Academy of Sciences, S ˇ olte ´sovej 4-6, 04001 Kos ˇice, Slovak Republic Received 29 August 2003; received in revised form 30 October 2003; accepted 27 November 2003 Abstract The ability of rumen ciliate protozoa to move in a unidirectional electrical field from the anode to the cathode was tested in large-volume electromigration equipment; the aim was to concentrate the microorganisms and clean them of impurities. During galvanotaxis in the freshly harvested rumen fluid and at a voltage of 10 V (I = 0.8 mA), cells of Isotricha (Isotricha prostoma, Isotricha intestinalis) were the first to swim towards the cathode; 1 min later, they were followed by Dasytricha ruminantium. Entodiniomorphous ciliates (small Entodiniae as well as large species) displayed minimum movement towards the cathode. The yield of electromigration of Entodinium caudatum from the in vitro culture ranged within 2 – 6% when using 75 – 100 V (10 mA) and 60 V (5 mA) voltage, respectively. At 10 V (0.8 mA), E. caudatum did not move towards the cathode. It is shown that the behavior of Trichostomatids (Dasytricha and Isotricha) facilitates separation by means of the tested large-volume equipment. Concentration and cleaning of Entodiniomorphous ciliates using galvanotaxis in the tested equipment proved to be ineffective. D 2004 Elsevier B.V. All rights reserved. Keywords: Electromigration; Entodinium caudatum; Galvanotaxis; In vitro culture; Rumen ciliate protozoa 1. Introduction Harvesting of the rumen ciliate protozoa from large volume in vitro cultures by centrifugation followed by repeated washing of the sediment to remove the bacteria and plant debris is often unsuccessful due to the presence of similarly sized plant debris and other ciliate cells. To overcome these problems, we tested the use of galvanotaxis to concentrate and purify the rumen protozoan cells. Motile protozoa placed between non-polarizable electrodes commonly migrate to either the anode or the cathode, a phenom- enon termed galvanotaxis or electromigration. Rumen ciliate protozoa migrate toward the cathode (Masson et al., 1952). The aim of this work was to investigate the ability of rumen ciliate protozoa from in vitro cultures to migrate from anode to cathode in an electromigration apparatus. This should help to con- centrate protozoan cells from mass cultures and sep- arate them from food debris. 2. Material and methods 2.1. Source of organisms Mixtures of rumen ciliates in freshly harvested rumen fluid were obtained from fistulated sheep. 0167-7012/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.mimet.2003.11.021 * Corresponding author. Tel.: +421-55-728-7841; fax: +421-55- 728-7842. E-mail address: kisiday@saske.sk (S. Kis ˇidayova ´). www.elsevier.com/locate/jmicmeth Journal of Microbiological Methods 57 (2004) 65 – 68