Research projects of current students

Marie Kim: Start date: Sep 2007; Nationality: Korean; Diplome thesis:
“Characterization of antimicrobial substances produced by Lactobacillus paraplantarum KNUC25 isolated from Kimchi”. (2007) Kyungpook National University, Daegu, South Korea; Research group:
AG Buckel, Dept. of Microbiology, Philipps-Universität Marburg; Research project description
My research is aimed to evaluate the biosyntheses of glutamate and benzoate in Syntrophus aciditrophicus. This anaerobic bacterium grows non-syntrophically on crotonate, which is oxidized to acetate with formation of ATP and reduced via glutaconyl-CoA mainly to cyclohexane-carboxylate and to some benzoate. Therefore, we assumed that glutaconyl-CoA decarboxylase must play an important role in this pathway catalyzing the carboxylation of crotonyl-CoA, which never has been obtained in vivo before. Glutamate is usually synthesized from acetyl-CoA via citrate, isocitrate and 2-oxoglutarate. However, no gene for Si-citrate synthase has been detected in the genome of S. aciditrophicus. The present study focuses on exploring an alternative way of glutamate biosynthesis in S. aciditrophicus. The discovery of a gene coding for Re-citrate synthase turned down the idea of glutaconyl-CoA and 2-hydroxyglutarate as precursors. Currently glutaconyl-CoA decarboxylase and Re-citrate synthase are characterized by gene expression in Escherichia coli as well as enzyme purification and kinetics.