Impact of Environmental Factors on Bacteriocin Promoter Activity in Gut-Derived Lactobacillus salivarius.
Bacteriocin production is regarded as a desirable probiotic trait that aids in colonization and persistence in the gastrointestinal tract (GIT). Strains of Lactobacillus salivarius, a species associated with the GIT, are regarded as promising probiotic candidates and have a number of associated bacteriocins documented to date. These include multiple class IIb bacteriocins (salivaricin T, salivaricin P, and ABP-118) and the class IId bacteriocin bactofencin A, which show activity against medically important pathogens. However, the production of a bacteriocin in laboratory media does not ensure production under stressful environmental conditions, such as those encountered within the GIT. To allow this issue to be addressed, the promoter regions located upstream of the structural genes encoding the L. salivarius bacteriocins mentioned above were fused to a number of reporter proteins (green fluorescent protein [GFP], red fluorescent protein [RFP], and luciferase [Lux]). Of these, only transcriptional fusions to GFP generated signals of sufficient strength to enable the study of promoter activity in L. salivarius. While analysis of the class IIb bacteriocin promoter regions indicated relatively weak GFP expression, assessment of the promoter of the antistaphylococcal bacteriocin bactofencin A revealed a strong promoter that is most active in the absence of the antimicrobial peptide and is positively induced in the presence of mild environmental stresses, including simulated gastric fluid. Taken together, these data provide information on factors that influence bacteriocin production, which will assist in the development of strategies to optimize in vivo and in vitro production of these antimicrobials.
Teagasc Food Research Centre, Moorepark, Fermoy, County Cork, Ireland.
Caitriona M
CM
Guinane
Teagasc Food Research Centre, Moorepark, Fermoy, County Cork, Ireland.
Clare
C
Piper
APC Microbiome Institute, University College Cork, Cork, Ireland School of Microbiology, University College Cork, Cork, Ireland.
Lorraine A
LA
Draper
Teagasc Food Research Centre, Moorepark, Fermoy, County Cork, Ireland APC Microbiome Institute, University College Cork, Cork, Ireland.
Paula M
PM
O'Connor
APC Microbiome Institute, University College Cork, Cork, Ireland School of Microbiology, University College Cork, Cork, Ireland.
Colin
C
Hill
APC Microbiome Institute, University College Cork, Cork, Ireland School of Science, Engineering & Food Science, University College Cork, Cork, Ireland.
R Paul
RP
Ross
Teagasc Food Research Centre, Moorepark, Fermoy, County Cork, Ireland APC Microbiome Institute, University College Cork, Cork, Ireland paul.cotter@teagasc.ie.
Paul D
PD
Cotter
D001430:Bacteriocins / Q000494:pharmacology*; D041981:Gastrointestinal Tract / Q000382:microbiology; D005798:Genes, Bacterial; D017930:Genes, Reporter; D007778:Lactobacillus / Q000235:genetics* / Q000378:metabolism; D019936:Probiotics / Q000378:metabolism*; D011401:Promoter Regions, Genetic
D001430:Bacteriocins