L-Carnitine Production in Pseudomonas fluorescens under phosphate starvation

Abstract

Glycerol is a by-product of the biodiesel industry and an important carbon source for bacterial growth. Phosphorus is an essential element in all living organisms and is utilized in numerous metabolic processes, such as the tricarboxylic acid (TCA) cycle and the electron transport chain. Without phosphorus, no organism can either grow or perform regular functions. In this study, we demonstrate that when the industrially-important microbe Pseudomonas fluorescens is deprived of phosphate, it elaborates a metabolic reconfiguration aimed at producing and secreting copious amounts of L-carnitine. To accomplish this biochemical adaptation, the organism bypassed the TCA cycle and utilized the glyoxylate shunt to generate a constant supply of L-carnitine through different metabolic networks. The upregulation of numerous enzymes including L-carnitine dehydrogenase (lcdH) and isocitrate lyase (aceA) mediated this process. The metabolic reprogramming triggered by phosphate may provide an effective means to transform an industrial waste into valuable L-carnitine.