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Title: Antibacterial activity and mechanism of action of ε-poly-L-lysine

Highlights: •Antibacterial activity and mechanism of ε-PL against E. coli O157:H7 was investigated. •Critical inhibitory factors toward the growth of E. coli O157:H7 by ε-PL was analyzed. •Cell membrane integrity and cell morphology of E. coli O157:H7 was affected by ε-PL. •A positive correlation between reactive oxygen species levels and ε-PL concentration in E. coli O157:H7 cells. •ε-PL induced the expression of different genes related to oxidative/redox stress, SOS response, virulence. -- Abstract: ε-Poly-L-lysine (ε-PL) is widely used as an antibacterial agent because of its broad antimicrobial spectrum. However, the mechanism of ε-PL against pathogens at the molecular level has not been elucidated. This study investigated the antibacterial activity and mechanism of ε-PL against Escherichia coli O157:H7 CMCC44828. Propidium monoazide-PCR test results indicated that the threshold condition of ε-PL for complete membrane lysis of E. coli O157:H7 was 10 μg/mL (90% mortality for 5 μg/mL). Further verification of the destructive effect of ε-PL on cell structure was performed by atomic force microscopy and transmission electron microscopy. Results showed a positive correlation between reactive oxygen species (ROS) levels and ε-PL concentration in E. coli O157:H7 cells. Moreover, the mortality of E. coli O157:H7 was reduced when antioxidant N-acetylcysteine was added. Resultsmore » from real-time quantitative PCR (RT-qPCR) indicated that the expression levels of oxidative stress genes sodA and oxyR were up-regulated 4- and 16-fold, respectively, whereas virulence genes eaeA and espA were down-regulated after ε-PL treatment. Expression of DNA damage response (SOS response) regulon genes recA and lexA were also affected by ε-PL. In conclusion, the antibacterial mechanism of ε-PL against E. coli O157:H7 may be attributed to disturbance on membrane integrity, oxidative stress by ROS, and effects on various gene expressions, such as regulation of oxidative stress, SOS response, and changes in virulence.« less
Authors:
;  [1] ;  [2] ; ;  [1] ;  [3] ;  [3] ;  [2] ;  [4] ;  [1]
  1. State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang (China)
  2. Jiangxi-OAI Joint Research Institute, Nanchang University, Nanchang (China)
  3. Ocean NanoTech LLC, 2143 Worth Lane, Springdale, AR 72764 (United States)
  4. Department of Environment and Chemical Engineering, Nanchang University, Nanchang (China)
Publication Date:
OSTI Identifier:
22242100
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemical and Biophysical Research Communications; Journal Volume: 439; Journal Issue: 1; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ANTIOXIDANTS; ATOMIC FORCE MICROSCOPY; CONCENTRATION RATIO; DNA DAMAGES; ESCHERICHIA COLI; GENES; LYSINE; OXIDATION; OXYGEN; POLYMERASE CHAIN REACTION; TRANSMISSION ELECTRON MICROSCOPY; VIRULENCE