Degradation of tetradecyltrimethylammonium by Pseudomonas putida

LIFFOURRENA, AS; LUCCHESI, GI

Villa General Belgrano, Córdoba

Workshop; Argentine Workshop on current topics in Pseudomonas and Burkholderia research; 2007

The purpose of this study was to evaluate the pure culture potential for the complete degradation of a cationic surfactant, tetradecyltrimethylammonium (TDTMA). P. putida utilized 50 mg l-1 of TDTMA as a sole carbon and nitrogen source. An inducible monooxygenase activity catalyzed the initial step of the degradation with the production of trimethylamine (TMA) and tetradecylalkanal. The next step involved the oxidation to tetradecanoic acid, detected by GC-MS, which would be further metabolized via b oxidation. The TMA produced is metabolized to NH3 and also accumulated inside the cell, affecting the bacterial growth and TDTMA consumption. To diminish the intracellular TMA level, the culture was supplemented with Al3+ 0.1 mM. The internal concentration of TMA, determined using the fluorochrome Morin, decreased and the growth increased in concordance with the total disappearance of TDTMA. Al+3 acted as a Lewis’ acid, playing a role in the control of TMA intracellular levels through of the reaction Al3+ + 2 :N(CH3)3 —› Al3+:[N(CH3)3]2. The monooxygenase activity was O2 and NAD(P)H dependent, inhibited by TMA and showed sigmoid velocity curves with respect to the substrate TDTMA (napp= 2.24 M; [S]05= 4.26 10-4 M). On the basis of these results, our aims are: i) To purify and to characterize kinetically the monooxygenase activity, ii) To determine the demethylation pathway of TMA.