OBSERVATIONS ON THE METABOLISM OFSARCINA LUTEA.II

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Abstract
The Qo2 of washed Sarcina lutea in water suspension at 22° C. in the relatively steady state averages 2.5. There is no untoward effect of crowding in heavy suspensions. The presence of NaCl does not modify the Qo2 until M/5 concentrations are reached, when a slight depression may result. The Qo2 is also unaffected by pH, at least between 7 and 8, or by the presence of phosphate buffer mixtures. Glucose addition causes a marked increase in the Qo2, the maximum being largely independent of glucose concentration. The extra oxygen used under the influence of glucose may be more than that required to fully oxidize it which, with other evidence, suggests a "specific dynamic action." Sodium lactate may increase the Qo2 in water suspension over twenty-fold. Its addition is always followed by a great rise of the respiratory rate, the maximum reached being independent of lactate concentration, at least between 0.05 and 2.0 per cent. The respiration falls rapidly back to normal after addition of small amounts, and the extra oxygen consumed accounts for full oxidation of the added lactate, both d and l forms. With larger concentrations of lactate, the increased respiration also falls after the initial maximum, but more slowly. This fall is not primarily due to removal of lactate nor accumulation of end products. Methylene blue added to a suspension in water doubles respiration at first, later depresses it. Added to one in glucose solution the same sequence appears. The Qo2 in glucose is increased only 50 per cent by the dye, but this is an absolute increase over twice that in water; so that glucose and methylene blue added together to a water suspension cause a greater increase in respiration than the sum of their separate effects. The dye added to lactate solutions seems to be depressant from the start. Thioglycollic acid doubles the respiration of a buffered water suspension. Sodium cyanide causes no inhibition of respiration up to concentrations of M/100 or somewhat stronger. This is true for the low respiration of suspensions in water, saline, or phosphate buffer and for the increases evoked by methylene blue, lactate and glucose. Extremely strong cyanide concentrations do depress, but even M/10 NaCN does not abolish more than 2/3 to 3/4 of the total respiration. Carbon monoxide containing 5 per cent oxygen has no effect on the respiration of a water suspension, but somewhat inhibits the increase in glucose and largely that in lactate. Light has little if any effect on the inhibition. The metabolism of Sarcina lutea is compared with that of other cell types.

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