ABSTRACT
Soil samples were screened for microorganisms selectively transforming FA. One of the isolated strains was identified as the bacterium Stenotrophomonas maltophilia by its phenotypic features and genotypic characterization by sequencing the ribosomal RNA gene. Using linoleic acid as substrate resulted in the formation of two major compounds. After liquid chromatographic isolation and separation, their structures were elucidated by HPLC-tandem MS, GC-MS, and NMR techniques to be 3-hydroxy-Z6-dodecenoic acid and 3-hydroxy-Z5,Z8-tetradecadienoic acid. In additional experiments, other FA, such as a-linolenic, oleic, palmitoleic, myristoleic, and cis-vaccenic acids, were converted to 3-hydroxylated metabolites of shorter chain lengths as well. Determination of the enantiomeric composition revealed highly enriched (R)-hydroxylation (88-98% enantiomeric excess).
Subject(s)
Fatty Acids/metabolism , Stenotrophomonas maltophilia/metabolism , Chromatography, High Pressure Liquid , Genotype , Hydroxylation , Magnetic Resonance Spectroscopy , Phenotype , Spectrometry, Mass, Electrospray Ionization , Stenotrophomonas maltophilia/geneticsABSTRACT
The soil bacterium Stenotrophomonas maltophilia was found to transform various long-chain fatty acids selectively into 3-hydroxy fatty acids of shorter chain length. Their chiral evaluation was performed by multidimensional gas chromatography (MDGC) on modified cyclodextrin phase comparing the enantiodistribution of 1,3-diol formed without loss of stereochemical information from a representative microbial product with those of synthetic (3RS)- and (3S)-1,3-diols. Enantiomeric excesses of 84-98% (R) were determined for the microbially produced 3-hydroxy acids. In addition, the CD exciton chirality method was applied to determine their absolute configuration. Derivatization with 9-anthryldiazomethane and 2-naphthoylimidazole led to the required bichromophoric structures. Their CD spectra displayed a positive first Cotton effect around 254 nm and a negative second Cotton effect around 237 nm, which confirmed the (R)-configuration of the bacterial products.
