Bacterial community and proteome analysis of fresh-cut lettuce as affected by packaging

Abstract

With the growing demand of fresh-cut vegetables, a variety of packaging films are produced specifically to improve safety and quality of the fresh vegetables over the storage period. The aim of our work was to evaluate the influence of different packaging films on the quality of fresh-cut lettuce analyzing changes in bacterial community composition and modifications at the proteome level, by means of culture-dependent/culture-independent methods and differential gel electrophoresis combined with mass spectrometry analysis. Total viable counts indicated the presence of a highly variable and complex microbial flora, around a mean value of 6.26 log10 CFU g(-1). Analysis of terminal-restriction fragment length polymorphism data indicated that bacterial communities changed with packaging films and time, showing differences in community composition and diversity indices between the commercially available package (F) and the new packages (A and C), in the first days after packaging. Also proteomic analysis revealed significant changes, involving proteins related to energy metabolism, photosynthesis, plant defense and oxidative stress processes, between F and A/C packages. In conclusion, microbiological and proteomic analysis have proved to be powerful tools to provide new insights into both the composition of leaf-associated bacterial communities and protein content of fresh-cut lettuce during the shelf-life storage process.

Emergence of Leuconostoc mesenteroides as a causative agent of oozing in carrots stored under non‐ventilated conditions

“…This might be associated with growth limitation in CO 2 ‐rich atmosphere, as reported, for example, during storage of meat under modified atmosphere (Stoops et al ., ). Similarly, decreased species richness and diversity have also been reported during storage of spinach and fresh‐cut lettuce under modified atmosphere (Lopez‐Velasco et al ., ; Di Carli et al ., ).…”

Omics approaches on fresh‐cut lettuce reveal global molecular responses to sodium hypochlorite and peracetic acid treatment

“…Changes in lettuce microbial community were also observed at qualitative level by means of analysis of T‐RFLP data. T‐RFLP has been shown to be effective at discriminating between microbial communities in a range of environments and has been previously used to profile fresh‐cut lettuce microbiota . The dendrogram resulting from UPGMA analysis showed a different distribution of bacterial populations in lettuce when subjected to the two different wash treatments, with a partial grouping of bacterial populations by treatment and time of storage.…”

“…Tryptic digests were desalted using C18 Pipette Tips (Agilent Technologies) as reported in the user manual and analyzed by nanoscale liquid chromatography coupled with electrospray ionization ion trap tandem mass spectrometry (nLC/ESI‐IT‐MS/MS) (Agilent Technologies). Samples were separated on HPLC‐Chip (40 nL Trap, 75 µm × 43 mm, 5 µm C‐18SB ZX; Agilent Technologies) as reported previously . An in‐house version of Mascot software (Version 2.5, Matrix Science, London, UK) was used to identify protein spots against the databases NCBInr (taxonomy Viridiplantae ) and Plant EST (http://www.ncbi.nlm.nih.gov; September 2014).…”

“…Spots of interest were treated as described previously. 16,17 Tryptic digests were desalted using C18 Pipette Tips (Agilent Technologies) as reported in the user manual and analyzed by nanoscale liquid chromatography coupled with electrospray ionization ion trap tandem mass spectrometry (nLC/ESI-IT-MS/MS) (Agilent Technologies). Samples were separated on HPLC-Chip (40 nL Trap, 75 μm × 43 mm, 5 μm C-18SB ZX; Agilent Technologies) as reported previously.…”

Postharvest processing decreases the richness of bacterial taxa in the phyllosphere of broccoli

“…Using high-throughput ribosomal RNA gene sequencing, many studies revealed that the foliar microbiota is more complex and diverse than previously expected (Rastogi et al 2013); numerous studies focus on the formation and development of the bacterial populations on fresh vegetables during their cultivation in the field (Rastogi et al 2012;Williams et al 2013;Dees et al 2015). The 'post-harvest' stage refers to the handling, packaging, transporting and storage of fresh vegetables following harvest; it is expected to affect the bacterial communities on field-grown vegetables because of the different environmental conditions during postharvest processing (Lopez-Velasco et al 2011;Di Carli et al 2016). Broccoli (Brassica oleracea var.…”