Biophysical and molecular basis of Listeria monocytogenes resistance towards enterocin CRL35

MASIAS E; DUPUY F; FARIZANO J; MINAHK CJ, SAAVEDRA L, SESMA F, MORERO R.; MINAHK C

Ciudad Autonoma de Buenos Aires

Congreso; Reunion Conjunta de Sociedades de Biociencias; 2017

Enterocin CRL35 is apediocin-like bacteriocin active against the foodborne pathogenListeria monocytogenes. Resistance to these peptides can beassociated with either downregulation of the receptor Man-PTS, aglucose transporter, or changes in the bacterial cell envelope. Theaim of this work was to analyze resistant strains of L. monocytogenesINS7 by means of biochemical and biophysical studies of the cells andtheir cytoplasmic membranes. Two resistant clones to enterocin CRL35,L. monocytogenes INS7 R2 and R3, which were characterized by 16S RNAgene sequencing and rep-PCR, had been isolated in our laboratory.Bacterial growth was studied in different culture media. Plasmamembranes of sensitive and resistant bacteria were obtained andcharacterized by infrared spectroscopy and Langmuir monolayertechniques. The results indicate that the growth rate of resistantstrains in TSB medium is slower than sensitive ones. On the otherhand, resistant cells were not able to grow in minimal defined mediumwith glucose as the sole energy source, suggesting that Listeriaresistant isolates have an alteration in the glucose transporterMan-PTS complex, which is the receptor of the IIa peptides in L.monocytogenes. The assessment of the bacterial cells membranesdemonstrated difference in the membrane lipids composition. Moreover,the interaction of enterocin CRL35 with the three Listeria lipidsamples displayed that this peptide could not get inserted into thehydrophobic core of resistant bacteria. These results indicate thatboth bacteriocin receptor downregulation and membrane structuralmodifications as well are involved in enterocin CRL35-resistance ofL. monocytogenes strainsp { margin-bottom: 0.25cm; line-height: 115%; }