Mechanism for temperature-dependent production of piscicolin 126.

Abstract

Piscicolin 126 is a class 2a bacteriocin produced by Carnobacterium maltaromaticum strains UAL26 and JG126. Whilst strain UAL26 shows temperature-dependent piscicolin 126 production, strain JG126 produces bacteriocin at any growth temperature. Several clones containing combinations of the ATP-binding cassette transporter (pisT) and transporter accessory (pisE) genes from JG126 and UAL26 were created and tested for bacteriocin production. Bacteriocin production at 25 °C was observed only for a clone containing both pisT and pisE from JG126 (U-T(J)E(J)) and a clone containing pisT from UAL26 and pisE from JG126 (U-BamT(U)E(J)). Therefore, the deletion of a single CG base pair located on pisE of UAL26 that results in a frameshift and truncation of PisE causes the temperature-dependent piscicolin 126 production. Bacteriocin production of UAL26 was induced at 25 °C by the addition of supernatant containing the autoinducer peptide (AIP); however, the antimicrobial activity was lost after two subsequent overnight cultivations due to the presumed lack of the AIP. Changes in membrane fluidity due to changes in temperature or the presence of 2-phenylethanol (PHE) affected bacteriocin production of UAL26, but not of clones U-T(J)E(J) or U-BamT(U)E(J). Similarly, increased membrane fluidity due to PHE addition reduced production of sakacin A in Lactobacillus sakei Lb706 and Lactobacillus curvatus LTH 1174. The mechanism involved in the temperature-dependent piscicolin 126 production was described. Due to the conformational change in PisE at 25 °C, the transport machinery was not able to translocate AIP. To the best of our knowledge, this is the first report that links membrane fluidity with the regulation of bacteriocin production.