Abstract
Pseudomonas fragi is usually isolated from chilled meats in relation to their spoilage, while many studies have shown that the application of modified atmosphere packaging (MAP) inhibits the spoilage potential of P. fragi. The effects of MAP on P. fragi NMC25 metabolism were determined in the present study by exposing this organism to different air conditions and comparing the resulting transcriptome profiles. We found 559 differentially expressed genes by RNA-seq, and the results revealed that MAP decreases the expression of genes involved in the electron transport chain (nuoAB), resulting in an inhibition of aerobic respiration. Meanwhile, MAP also induced the downregulation of genes responsible for ATP-binding cassette transporters, flagellar and type I fimbrial proteins, and DNA replication and repair, which may further influence nutrient uptake, motility, and growth. In addition, NMC25 cells modified their pathways for energy production, amino acid synthesis, membrane lipid composition, and other metabolic patterns to adapt to MAP. These data show that P. fragi NMC25 survives under MAP but reduces part of its metabolism related to its spoilage ability.
Highlights
Pseudomonas spp. constitute the main spoilage microorganism of meat stored in aerobic refrigerated conditions (Nychas et al, 2008; Mohareb et al, 2015; Rouger et al, 2017)
The aim of this study is to provide a global view of gene expression in P. fragi NMC25 in response to modified atmosphere packaging (MAP) conditions, leading to understanding the cellular strategies that are employed under MAP and to proposing a potential mechanism for the inhibition of spoilage activity under MAP
To compare the lifestyle of P. fragi NMC25 under air and MAP, we compared the transcriptome profile of cells growing on meat under MAP with that of cells growing under air using RNA-seq
Summary
Pseudomonas spp. constitute the main spoilage microorganism of meat stored in aerobic refrigerated conditions (Nychas et al, 2008; Mohareb et al, 2015; Rouger et al, 2017). These species are responsible for meat physical damage, off-odor production, and slime formation. Pseudomonas fragi is currently recognized as the most abundant member of the Pseudomonas spp. on fresh meat, which is a suitable substrate for P. fragi growth (Ercolini et al, 2010). Spoilage is often associated with bacterial enzyme functions or metabolic activities. Researchers are attempting to correlate these bacterial metabolic activities with spoilage appearance. Previous studies showed that spoilage bacteria produce malodorous volatile compounds through their ability
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