Identification and characterization of fatty acid alkyl esterases found in Staphylococcus aureus (1002.3)

Identification and Characterization of Fatty Acid Alkyl Esterases Found in Staphylococcus aureus Alternative energy is a major field of current research. Biodiesel, a mixture of fatty acid alkyl esters, is the most versatile biofuel in current use. This is due to the fact that it is similar enough to gasoline that it is compatible with the diesel engines found throughout the existing global infrastructure. Biodiesel precursor lipids are abundant in cultivated feedstock organisms such as algae and bacteria. However, the standard process for converting oil to biodiesel is heat‐intensive and requires complete removal of water, greatly reducing the net energy gained in its manufacture. Our work constitutes an attempt to explore enzymatic synthesis of biodiesel with lipids like those derived from emerging fuel crops. Previous literature describes fatty acid alkyl ester formation in Staphylococcal lesions, formed by partially characterized esterase activity from an unidentified source. We have identified the enzymes responsible for this activity by using a combination of size exclusion chromatography, gas chromatography‐mass spectrometry, and mass spectrometric protein sequencing. These two highly similar enzymes in the glycerol ester hydrolase (geh) family of proteins catalyze the synthesis of fatty acid alkyl esters in aqueous conditions at or near room temperature. We have demonstrated that other, similar lipases do not exhibit this behavior. We have expressed one of these Staphylococcal esterases in E. coli , and shown via gas chromatography that the expressed protein catalyzes the formation of fatty acid alkyl esters. Based on sequence similarity to homologous proteins that have already been crystallized, we have predicted a structure for these enzymes and intend to engineer mutants with higher rates of catalysis. Grant Funding Source : NSF