| Summary: | When Pseudomonas aeruginosa ATCC 9027 var. RCII, a chloramphenicol-tolerant substrain, is grown in a phosphate limited, complex medium, along with the drug (150 (mu)g/ml), it accumulates high intracellular levels of inorganic phosphate and fails to synthesize normal levels of alkaline phosphatase and pyocyanine. Glucose transport is additionally hindered, and, accordingly, extracellular glucose is mainly oxidized to 2-ketogluconate. The preference of NAD(H)-linked enzymatic activities suggests the absence of transhydrogenase activity. The cytochrome content and intracellular ATP pool of this substrain are also greater. The ATP pool is further augmented when chloramphenicol is omitted from the medium. H('+)/O analysis confirmed that the substrain gained one additional ATP conservation site. Drug tolerance in P. aeruginosa ATCC 9027 is clearly accompanied by greater energy production. Slower growth arises since more energy is delegated towards maintenance and survival in the presence of the drug.
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