Enhanced antimicrobial activity based on a synergistic combination of sublethal levels of stresses induced by UV-A light and organic acids
Article
de Oliveira, E., Cossu, A., Tikekar, R. and Nitin, N. 2017. Enhanced antimicrobial activity based on a synergistic combination of sublethal levels of stresses induced by UV-A light and organic acids. Applied and Environmental Microbiology. 83 (11). https://doi.org/10.1128/aem.00383-17
Type | Article |
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Title | Enhanced antimicrobial activity based on a synergistic combination of sublethal levels of stresses induced by UV-A light and organic acids |
Authors | de Oliveira, E., Cossu, A., Tikekar, R. and Nitin, N. |
Abstract | The reduction of microbial load in food and water systems is critical for their safety and shelf life. Conventionally, physical processes such as heat or light are used for the rapid inactivation of microbes, while natural compounds such as lactic acid may be used as preservatives after the initial physical process. This study demonstrates the enhanced and rapid inactivation of bacteria based on a synergistic combination of sublethal levels of stresses induced by UV-A light and two food-grade organic acids. A reduction of 4.7 ± 0.5 log CFU/ml in Escherichia coli O157:H7 was observed using a synergistic combination of UV-A light, gallic acid (GA), and lactic acid (LA), while the individual treatments and the combination of individual organic acids with UV-A light resulted in a reduction of less than 1 log CFU/ml. Enhanced inactivation of bacteria on the surfaces of lettuce and spinach leaves was also observed based on the synergistic combination. Mechanistic investigations suggested that the treatment with a synergistic combination of GA plus LA plus UV-A (GA+LA+UV-A) resulted in significant increases in membrane permeability and intracellular thiol oxidation and affected the metabolic machinery of E. coli. In addition, the antimicrobial activity of the synergistic combination of GA+LA+UV-A was effective only against metabolically active E. coli O157:H7. In summary, this study illustrates the potential of simultaneously using a combination of sublethal concentrations of natural antimicrobials and a low level of physical stress in the form of UV-A light to inactivate bacteria in water and food systems. |
Keywords | food-grade antimicrobial; gallic acid; lactic acid; microbial inactivation; sublethal stress; UV-A; light synergism |
Publisher | American Society for Microbiology (ASM) |
Journal | Applied and Environmental Microbiology |
ISSN | 0099-2240 |
Electronic | 1098-5336 |
Publication dates | |
Online | 17 May 2017 |
01 Jun 2017 | |
Publication process dates | |
Deposited | 25 Nov 2019 |
Accepted | 27 Mar 2017 |
Output status | Published |
Digital Object Identifier (DOI) | https://doi.org/10.1128/aem.00383-17 |
Scopus EID | 2-s2.0-85019937552 |
Web of Science identifier | WOS:000401471600013 |
Language | English |
https://repository.mdx.ac.uk/item/8866z
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