title: Metabolomic analysis of antimicrobial mechanisms of ε-poly-L-lysine on Saccharomyces cerevisiae.
abstract: ε-Poly-L-lysine (ε-PL), a naturally occurring amino acid homopolymer, has been widely used as a food preservative. However, its antimicrobial mechanism has not been fully understood. This study investigated the antimicrobial mode of action of ε-PL on a yeast, Saccharomyces cerevisiae. When treated with ε-PL at the concentration of 500 μg/mL, cell mortality was close to 100% and the phospholipid bilayer curvature, pores, and micelles on the surface of S. cerevisiae were clearly observed by scanning electron microscopy (SEM). At the level of 200 μg/mL, ε-PL significantly inhibited the cell growth of S. cerevisiae. When treated with 50 μg/mL ε-PL, the yeast cell was able to grow but the cell cycle was prolonged. A significant increase in cell membrane permeability was induced by ε-PL at higher concentrations. Metabolomics analysis revealed that the ε-PL stress led to the inhibition of primary metabolic pathways through the suppression of the tricarboxylic acid cycle and glycolysis. It is therefore proposed that the microbiostatic effect of ε-PL at lower levels on S. cerevisiae is achieved by inducing intracellular metabolic imbalance via disruption of cell membrane functions. Moreover, the results suggested that the antimicrobial mechanism of ε-PL on S. cerevisiae can in fact change from microbiostatic to microbicidal when the concentration of ε-PL increased, and the mechanisms of these two modes of action were completely different.
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, and‡College of Biotechnology, Tianjin University of Science and Technology , Tianjin 300457, People's Republic of China.
authors.forename: Tao
authors.initials: T
authors.lastname: Bo
authors.forename: Miao
authors.initials: M
authors.lastname: Liu
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhong
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.forename: Qin-Zhi
authors.initials: QZ
authors.lastname: Su
authors.forename: Zhi-Lei
authors.initials: ZL
authors.lastname: Tan
authors.forename: Pei-Pei
authors.initials: PP
authors.lastname: Han
authors.forename: Shi-Ru
authors.initials: SR
authors.lastname: Jia
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D053858:Metabolic Networks and Pathways / Q000187:drug effects; D011107:Polylysine / Q000494:pharmacology*; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D000935:Antifungal Agents; D011107:Polylysine