The Lcn972 Bacteriocin-Encoding Plasmid pBL1 Impairs Cellobiose Metabolism in Lactococcus lactis

Abstract

pBL1 is a Lactococcus lactis theta-replicating 10.9-kbp plasmid that encodes the synthetic machinery of the bacteriocin Lcn972. In this work, the transcriptomes of exponentially growing L. lactis strains with and without pBL1 were compared. A discrete response was observed, with a total of 10 genes showing significantly changed expression. Upregulation of the lactococcal oligopeptide uptake (opp) system was observed, which was likely linked to a higher nitrogen demand required for Lcn972 biosynthesis. Strikingly, celB, coding for the membrane porter IIC of the cellobiose phosphoenolpyruvate-dependent phosphotransferase system (PTS), and the upstream gene llmg0186 were downregulated. Growth profiles for L. lactis strains MG1363, MG1363/pBL1, and MG1363 ⌬celB grown in chemically defined medium (CDM) containing cellobiose confirmed slower growth of MG1363/pBL1 and MG1363 ⌬celB, while no differences were observed with growth on glucose. The presence of pBL1 shifted the fermentation products toward a mixed acid profile and promoted substantial changes in intracellular pool sizes for glycolytic intermediates in cells growing on cellobiose as determined by highpressure liquid chromatography (HPLC) and nuclear magnetic resonance (NMR). Overall, these data support the genetic evidence of a constriction in cellobiose uptake. Notably, several cell wall precursors accumulated, while other UDP-activated sugar pools were lower, which could reflect rerouting of precursors toward the production of structural or storage polysaccharides. Moreover, cells growing slowly on cellobiose and those lacking celB were more tolerant to Lcn972 than cellobiose-adapted cells. Thus, downregulation of celB could help to build up a response against the antimicrobial activity of Lcn972, enhancing self-immunity of the producer cells.

Stress Response and Adaptation of Listeria monocytogenes 08-5923 Exposed to a Sublethal Dose of Carnocyclin A

“…This indicates that the downregulation of these genes was due to the adaptation to CCLA. The upregulation of 54 -regulated mptAB and cel detected by cDNA microarray after 4 h of exposure to CCLA indicates an immediate adaptive response of Listeria cells, as the mannosespecific (7) and cellobiose-specific PTS systems are receptors for bacteriocins (20), and the upregulation of mannose-specific PTS systems has been observed in bacteriocin-sensitive cells (21,22). Gong et al (3) demonstrated that CCLA forms ion-selective channels in lipid bilayers, which indicates that CCLA interaction with membranes is not receptor mediated.…”

Target recognition, resistance, immunity and genome mining of class II bacteriocins from Gram-positive bacteria

“…In this context it is interesting to note that Campelo et al (2011) found a link between sensitivity to the bacteriocin Lcn972 and uptake of cellobiose via the membrane-bound cellobiose-PTS protein CelB. We have also identified mutants that are resistant to different class II bacteriocins, which often have impaired metabolism of certain sugars, including lactose, arbutin and gentiobiose (unpublished data).…”

Two Phages, phiIPLA-RODI and phiIPLA-C1C, Lyse Mono- and Dual-Species Staphylococcal Biofilms

“…Plates were incubated at 37°C, and growth was monitored in a Benchmark Plus microplate spectrophotometer (Bio-Rad Laboratories) until the control samples reached an OD 600 of 0.9 Ϯ 0.1. Growth rates were estimated by linear regression after plotting the ln(OD 600 ) as a function of time during the exponential growth phase, as described previously (27). The adsorption kinetics and the adsorption rate constants (k) of the phages were calculated as previously described (28).…”