206 SCHULTZ, DUMONT, AND KYTE 



with a capacity of 15 ml, each containing 4.5 ml of cell suspension, 

 were used. A paper wick saturated with 15% KOH solution was 

 placed in the center well to absorb free CO2, and 0.5 ml of 

 condensate at a concentration 10 times that desired for final testing 

 was placed in the sidearm of the reaction vessel and later was mixed 

 with the sample. Experiments were performed with final concentra- 

 tions of 1 through 5%. Experimental and control samples were 

 monitored at 15-min intervals for a total of 300 min, and total 

 oxygen consumed (/i liter) was recorded for each time point. The 

 immediate effect of gasifier condensate on respiration was deter- 

 mined with a biological oxygen monitor (Yellow Springs Instrument 

 Company, Inc.) equipped with a platinum— oxygen electrode. The 

 temperature was stabilized at 28° C, and the rate of oxygen 

 consumption (%/min) was recorded. For each test a 3-ml aliquot of 

 cells was aerated for 3 min in the sample chamber before recording 

 the data. The 0.3-ml aliquots of lOx condensate or sterile medium 

 were added directly to the sample chambers, which contained either 

 the cell suspension or sterile medium, and the samples were 

 continuously stirred. Oxygen consumption was recorded before, 

 during, and immediately after the test solutions were added to the 

 chambers. 



Electron Microscopy 



The test animals were removed from the condensate solution at 

 intervals of 15, 30, 60, 120, and 360 min for electron microscopy 

 and were fixed according to the technique of Kennedy and 

 Richardson (1969). Fixed cells were dehydrated in ethanol and 

 propylene oxide and then infiltrated with and embedded in Epon 

 (Shell Chemical Company). Thin sections stained with uranyl acetate 

 and lead citrate were viewed with an electron microscope (Hitachi) 

 operated at 75 kV. 



Population Growth and Density 



The effects of gasifier condensate on growth rates and population 

 densities of Tetrahymena were measured spectrophotometrically. 

 Optically matched 18- by 150-mm glass culture tubes were used, and 

 experiments were performed with final concentrations of 0.1, 0.2, 

 0.4, 0.6, 0.8, and 1% condensate. Each tube, containing 10 ml of 

 medium, was inoculated with 0,2 ml of log-growth-phase culture 

 and maintained in a water bath at 28° C. Absorbance at 540 nm was 

 used to estimate population density. The period of exponential 

 growth was determined for each test concentration, and the best line 



