Identification of a putative citrulline transporter in Lactobacillus brevis 2-34

Abstract:

[Background] Citrulline and ethyl carbamate are hazards generated during rice wine fermentation. From rice wine fermentation broth Lactobacillus brevis 2-34 is isolated with the potential to reabsorb citrulline. [Objective] To identify genes encoding citrulline transporters in this strain will help its effective application in rice wine fermentation. [Methods] With vectors pRSFDuet-1 and pETDuet-1, citrulline metabolism-related enzymes of L. brevis 2-34, including arginine/ornithine antiporter, arginine deaminase, ornithine carbamyltransferase, as well as the two putative citrulline transporters, C4-dicarboxylate anaerobic carrier and AO antiporter, were expressed in Escherichia coli C43(DE3). [Results] Recombinant E. coli had similar citrulline reabsorption ability as L. brevis 2-34. Both putative transporters could absorb extracellular citrulline, and the transporting capability of DcuC was much stronger. [Conclusion] DcuC and AO antiporter are citrulline transporters in L. brevis 2-34.