Assimilation of γ-butyrobetaine, and d-and l-carnitine by resting cell suspensions of Acinetobacter calcoaceticus and Pseudomonas putida

Abstract

The metabolic pattern of utilization of [1,2,3,4-¹⁴C, methyl-³H] γ-butyrobetaine and d-and l-[1-¹⁴C, methyl-³H]carnitine has been examined with variously grown resting cell suspensions of Acinetobacter calcoaceticus and Pseudomonas putida. Ps. putida grown on d, l-carnitine as the sole source of carbon, degraded only l-carnitine with stoichiometric accumulation of glycinebetaine. Alternatively, when grown on γ-butyrobetaine, Ps. putida rapidly metabolized γ-butyrobetaine, and to a lesser but significant extent, both d-and l-carnitine with equivalent formation of trimethylamine and degradation of the betaine carbon skeleton. Ac. calcoaceticus grown on either d,l-carnitine or γ-butyrobetaine, effectively utilized all three betaines at nearly the same rates. Disappearance of each of these quarternary ammonium compounds was accompanied by stoichiometric formation of trimethylamine and degradation of the carbon backbone. Utilization of the betaines and corresponding formation of trimethylamine by resting cell suspensions of appropriately grown Ac. calcoaceticus and Ps. putida, was essentially abolished under conditions of anaerobiosis and severely impaired in the presence of sodium cyanide, sodium azide, 2,4-dinitrophenol or 2,2′-bipyridine. The results of the present investigations with resting cell suspensions of both Ac. calcoaceticus and Ps. putida do not support an earlier suggestion that γ-butyrobetaine degradation in these organisms proceeds by its prior hydroxylation to l-carnitine. Indeed, disrupted cell-free preparations of Ac. calcoaceticus and Ps. putida grown on either d,l-carnitine or γ-butyrobetaine showed no detectable γ-butyrobetaine hydroxylase activity.