ISSN:
1574-6941
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Abstract: The rates of ingestion of bacteria and of accumulation of bacterial biomass by hungry Pteridomonas danica and Paraphysomonas imperforata were measured using dual radioactive-labelled bacteria in experiments lasting 4–8 h. Pteridomonas continuously consumed 4–5 bacteria h−1 throughout experiments lasting 8 h, irrespective of bacterial concentration above a threshold of about 5 × 105 bacteria ml−1, and continued to catch bacteria even below this density. The clearance rate of about 1 nl cell−1 h−1 at higher bacterial concentrations increased three or four times as bacterial numbers fell. Paraphysomonas cells, with only half the biomass of Pteridomonas, ingested up to 10 bacteria h−1 at high bacterial concentrations, and gradually reduced the feeding rate, effectively ceasing to feed at 106 bacteria ml−1; their initial clearance rate of 1–2.5 nl cell−1 h−1 subsequently fell as low as 0.1 nl cell−1 h−1. Estimation of feeding rate by extrapolation from short-term experiments on such flagellates requires extreme caution. These flagellates, starved to levels typical of the natural environment, accumulated ingested bacterial biomass at an efficiency of between 16 and 21%, indicating that in nature they would recycle 80% or more of the nutrients contained in their food.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1574-6941.1995.tb00127.x
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