CHANGES IN THE GLUTATHIONE (GSH) METABOLISM OF PENICILLIUM-CHRYSOGENUM GROWN ON DIFFERENT NITROGEN-SOURCES, SULFUR-SOURCES AND CARBON-SOURCES

Changes in the de novo glutathione (GSH) synthesis (GSH producing acti vity; GPA), in the gamma-glutamyltranspeptidase (gamma GT) and GSH red uctase (GR) activities as well as in the GSH pools were measured in a high beta-lactam producing strain of Penicillium chrysogenum in the pr esence of different nitrogen, sulphur and carbon sources. When (NH4)(2 )HPO4 was used as a nitrogen source both the specific GPA and the spec ific gamma GT activity were significantly lower than those observed wi th Na-Glu, meanwhile nitrogen starvation increased the gamma GT activi ty only. Although neither the addition of ammonium ions nor the withdr awal of nitrogen sources influenced the GSH pool during a 10 h cultiva tion the addition of the sulphur containing amino acids cysteine (Cys) or methionine (Met) at a concentration of 20 mM increased considerabl y both the specific GPA and the intracellular GSH levels. Nevertheless , GPA decreased significantly when either Cys or Met was added at a th ree times higher concentration. When glucose was replaced by lactose a s a carbon source or during carbon starvation the GPA values and the G SH concentrations were higher while the GR activities were lower than those observed with glucose. Nevertheless, no changes in either the en zyme activities or the GSH levels were detected when glucose was repla ced with 2-deoxy-D-glucose or glucose together with caffeine was added to the culture media.