CARNITINE RESEMBLES CHOLINE IN THE INDUCTION OF CHOLINESTERASE, ACID-PHOSPHATASE, AND PHOSPHOLIPASE-C AND IN ITS ACTION AS AN OSMOPROTECTANT IN PSEUDOMONAS-AERUGINOSA

The present study demonstrates that under conditions of iso or hyperos molarity, P. aeruginosa utilized carnitine as the carbon, nitrogen or carbon and nitrogen sources. As occurred in the case of choline, the b acteria synthesized cholinesterase (ChE), acid phosphatase (Ac.Pase) a nd phospholipase C (PLC) under any of these conditions and in the pres ence of high or low P-i concentrations. Carnitine acted as an osmoprot ectant when the cells were grown in the presence of preferred carbon a nd nitrogen sources and high NaCl concentrations. Under these conditio ns the three enzyme activities were not produced. The osmotically stre ssed bacteria grown under any of the above conditions accumulated beta ine. Its presence indicated that carnitine may be metabolized by P. ae ruginosa to produce betaine which could account for the induction of t he three enzyme activities or its action as an osmoprotectant. The pho sphatidylcholine encountered in the host cell membranes allows the bac teria to obtain free choline by the coordinated action of PLC and Ac.P ase. Since the consequence of this action may be cell disruption, the increase of free carnitine in the natural environment of the bacteria is also possible. These two compounds, choline and carnitine, acting i n conjunction or separately, may increase the production of PLC and Ac .Pase activities by P. aeruginosa and thus enhance the degradative eff ect upon the host cells.