Chemotaxis in Rumen Protozoa
Movement of some ciliated protozoa towards solutions containing sugars or organic acids was studied. These protozoa live in the rumen of cows. The rumen is a part of their stomach and a vital organ because it is where microbial (bacterial and protozoal) fermentation occurs. Solutions (1 mM) of some soluble sugars and organic acids were compared to autoclaved rumen fluid (control). Capillary tubes (40 ¼L) were filled with one solution, immersed in rumen fluid (from a lactating Holstein cow before feeding) for 30 minutes, and incubated under CO2 at 40ÚC. After incubation, protozoa in each tube were counted using a microscope. Control, glucose and other two solutions were tested twice in a single day and the experiment was repeated on subsequent days until all solutions has been tested. Control tubes containing an average of only 2.5 holotrich protozoa after 30 minutes of incubation; whereas, tubes containing fructose or glucose had 45.3 and 41.3 protozoa, respectively. Some attraction to galactose and citrate was indicated because tubes containing these averaged 9.6 and 10.7 holotrichs, respectively. Counts for solutions of malate (3.0), xylose (6.0), arabinose (1.9), succinate (3.3), and fumarate (3.4) did not differ from the control. In conclusion, these protozoa were highly attracted to glucose and fructose, but much less such to solutions of other sugars or organic acids. By competing with other microbes for these substances, protozoa help reduce the rate production of another organic acid (lactate) which, in turn, helps stabiliza digestion in the cow.
School:
University of Illinois at Urbana-Champaign
Department:
Biology
Research Advisor:
Michael R. Murphy
Department of Research Advisor:
Animal Sciences
Year of Publication:
2002