31P-NMR evidence for cytoplasmic acidification and phosphate extrusion in syringomycin-treated cells of Rhodotorula pilimanae.

31P-NMR spectroscopy was used to investigate the effects of the phytotoxin, syringomycin, on phosphate metabolism and intracellular pH changes in the yeast Rhodotorula pilimanae. Syringomycin, at levels between 20 and 60 units per 10(8) cells, caused a cellular efflux of orthophosphate. At 40 and 60 unit per 10(8) cells, the efflux was accompanied by a decrease in polyphosphate and an acidification of the cytoplasm. At low temperatures (5 degrees C) and with 75 units per 10(8) cells, these effects were more rapid and pronounced. The efflux of phosphate was confirmed by chemically assaying extracellular phosphate after syringomycin treatment.