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Enterocin LD3 from Enterococcus hirae LD3 causing efflux of intracellular ions and UV‐absorbing materials in Gram‐negative bacteria
Author(s) -
Sheoran Poonam,
Tiwari Santosh Kumar
Publication year - 2019
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.14203
Subject(s) - micrococcus luteus , bacteria , nucleic acid , bacteriocin , efflux , bacterial cell structure , biochemistry , escherichia coli , gram positive bacteria , gram negative bacteria , biology , chemistry , microbiology and biotechnology , genetics , gene
Aims To understand the bactericidal action of enterocin LD3 against Gram‐negative bacteria. Methods and Results Minimum inhibitory concentration ( MIC ) of enterocin LD 3 against Micrococcus luteus MTCC 106 and Escherichia coli NCDC 135 was 80 and 112 μ g ml −1 , and minimum bactericidal concentration ( MBC ) was 128 and 180 μ g ml −1 , respectively. The efflux of potassium ion (K + ) was 14 and 13 ppm and electrical conductivity 10·5 and 8·3 mS cm −1 in cell‐free supernatant of MIC ‐treated cells of M. luteus and E. coli respectively. The increased absorbance ( OD 260/280 ) 0·422/0·260 and 0·110/0·075 in the bacteriocin‐treated cells of M. luteus MTCC 106 and E. coli , NCDC 135, respectively, suggested the release of nucleic acids and proteins. The higher infrared absorbance at 1451·82 and ~1094·30 cm −1 further suggested its interaction with cell membrane and nucleic acids of the target bacteria. The interaction of bacteriocin with nucleic acids was also confirmed using gel retardation assay. Transmission electron microscopy of the bacteriocin‐treated cells revealed disruption of cell membrane and leakage of cytoplasmic contents. Conclusions Enterocin LD 3 demonstrates bactericidal activity against Gram‐negative bacteria interacting with cell membrane and nucleic acids. Significance and Impact of the Study The study discloses the possible mechanism of action of enterocin LD 3 against Gram‐negative bacteria which is a rare phenomenon.