Ref ID : 4204
William D. Taylor; The Effect of Grazing by a Ciliated Protozoan on Phosphorus Limitation of Heterotrophic Bacteria in Batch Culture. J.Protozool. 33(1):47-52, 1986
Reprint
In File
Notes
The yield of the bacterium Enterobacter aerogenes and the ciliate Colpidium colpoda was dependent on initial phosphorus concentrations in batch cultures containing 125 or 250 mg/liter glutamate and 50-1000 µg/liter phosphorus. For both, yield per unit phosphorus declined at higher phosphorus concentrations. A marked decline in growth rate in bacterial cultures was coincident with the depletion of dissolved phosphorus and the development of rapid orthophosphate turnover times. Colpidium introduced to these cultures consumed about 16,000 bacteria/hr/ciliate while multiplying exponentially and relieved phosphorus limitation, as indicated by a longer turnover-time for phosphate. The longer turnover-time was due to the reduction of bacterial numbers; in cultures with ciliates, bacteria appear to be more active in taking up phosphate, and much of the total phosphorus accumulates in ciliates. Ciliates released both inorganic and organic phosphorus, but the organic phosphorus did not accumulate to excess in the cultures to an extent that would indicate that it is less used by bacteria. Although ciliates release enough phosphorus to account for ca. 20% of the bacterial uptake, ciliates appear to behave as phosphorus sinks as much as phosphorus recyclers in these closed systems.