Pyruvate is an important starting material widely used as an effective precursor in the chemical, drug and agrochemical industries. At present time pyruvate can be produced by both fermentation and enzyme-catalyzed reaction. Nowadays more and more attentions were focused on the enzyme-catalyzed reaction for environmental reasons and the cost of the raw material. It is very important to find an enzyme which has high catalyzing efficiency utilized for pyruvate producing. There are three kinds of enzymes that can catalyze lactate to pyruvate. One is named flavocytochrome b2 which was seldom used to produce pyruvate from lactate. Another is lactate oxidase (LOX) which were found in many species. The last one is lactate dehydrogenase (LDH) which was divided into two types as follows: nicotinamide adenine dinucleotide-linked LDH (nLDH) and nicotinamide adenine dinucleotide-independent LDH (iLDH).Fortunately we found a useful strain of Pseudomonas stutzeri SDM which can grow well at simple mediums containing lactate as sole carbon source. It is the first time that this bacterial was found to be able to produce pyruvate. However the enzymes responsible for the conversion of lactate to pyruvate have not been identified and a little was known about the metabolic mechanism of this strain.This paper mainly focused on:1. P. stutzeri SDM which was newly isolated from soil could grow in a simple medium containing lactate as sole carbon source. When it was cultured on lactate-containing medium the free cells had the capacity of coupling the oxidation of D- and L-lactate and producing pyruvate. To get clearly insight into the lactate-utilization mechanisms two-dimensional gel electrophoresis (2DE) were carried out on total cell lysates. High performance liquid chromatography (HPLC) was performed to detect tricarboxylic acid cycle intermediate and several metabolites including malic acid, pyruvic acid, lactic acid, acetic acid, α-ketoglutaric acid and