Current Advances in the Concept of Quorum Sensing-Based Prevention of Spoilage of Fish Products by Pseudomonads

The effect of Dunaliella salina extracts on the adhesion of Pseudomonas aeruginosa to 3D printed polyethylene terephthalate and polylactic acid

Polyethylene terephthalate (PET) and polylactic acid (PLA) are among the polymers used in the food industry. In this study, crude extracts of Dunaliella salina were used to treat the surface of 3D printed materials studied, aiming to provide them with an anti-adhesive property against Pseudomonas aeruginosa. The hydrophobicity of treated and untreated surfaces was characterized using the contact angle method. Furthermore, the adhesive behavior of P. aeruginosa toward the substrata surfaces was also studied theoretically and experimentally. The results showed that the untreated PLA was hydrophobic, while the untreated PET was hydrophilic. It was also found that the treated materials became hydrophilic and electron-donating. The total energy of adhesion revealed that P. aeruginosa adhesion was theoretically favorable on untreated materials, while it was unfavorable on treated ones. Moreover, the experimental data proved that the adhesion to untreated substrata was obtained, while there was complete inhibition of adhesion to treated surfaces.

Characterization and interactions of spoilage of Pseudomonas fragi C6 and Brochothrix thermosphacta S5 in chilled pork based on LC-MS/MS and screening of potential spoilage biomarkers

Pseudomonas and Brochothrix are the main spoilage organisms in pork, and each of these plays an essential role in the spoilage process. However, the effect of co-contamination of these two organisms in pork has not been elucidated. The changing bacterial communities during spontaneous spoilage of pork at 4 °C were evaluated using high-throughput sequencing. The dominant spoilage bacteria were isolated and these were identified as Pseudomonas fragi C6 and Brochothrix thermosphacta S5. Chilled pork was then experimentally contaminated with these strains, individually and in combination, and the progression of spoilage was assessed by analyzing various physicochemical indicators. These included total viable counts (TVC), pH, color, total volatile basic nitrogen (TVB-N), and detection of microbial metabolites. After 7 days of chilled storage, co-contaminated pork produced higher TVC and TVB-N values than mono-contaminated samples. Metabolomic analysis identified a total of 8,084 metabolites in all three groups combined. Differential metabolites were identified, which were involved in 38 metabolic pathways. Among these pathways, the biosynthesis of alkaloids derived from purine and histidine was identified as an important pathway related to spoilage. Specifically, histidine, histamine, AMP, IMP, GMP, succinic acid, and oxoglutaric acid were identified as potential spoilage biomarkers. The study showed that the combined presence of P. fragi C6 and B. thermosphacta S5 bacteria makes chilled pork more prone to spoilage, compared to their individual presence. This study provides insights that can assist in applying appropriate techniques to maintain quality and safety changes in meat during storage and further the assessment of freshness.

Gallic and ferulic acids suppress proteolytic activities and volatile trimethylamine production in the food-borne spoiler Rahnella aquatilis KM05

BACKGROUND

Rahnella aquatilis is a recognised microbial threat that alters the sensory properties of seafood. The high frequency with which R. aquatilis is isolated from fish has prompted a search for alternative preservatives. In the present study, in vitro and fish-based ecosystem (raw salmon-based medium) approaches were used to validate the antimicrobial effects of gallic (GA) and ferulic (FA) acids against R. aquatilis KM05. The results were compared with data describing the response of KM05 to sodium benzoate. Bioinformatics data of the whole genome were used to analyse the potential for fish spoilage by KM05 in detail, and the results revealed the main physiological characteristics that underlie reduced seafood quality.

RESULTS

In the KM05 genome, the most abundantly enriched Gene Ontology terms were 'metabolic process', 'organic substance metabolic process' and 'cellular process'. Through an evaluation of the Pfam annotations, 15 annotations were found to be directly involved in the proteolytic activity of KM05. Peptidase_M20 was the most abundantly represented (abundance value of 14060). Proteins representing the CutC family (abundance value of 427) indicated the potential for KM05 degradation of trimethyl-amine-N-oxide. Subinhibitory concentrations of GA and FA suppressed the proteolytic activities of KM05 both in vitro and in RS medium by an average of 33-45%. These results were confirmed by quantitative real-time PCR experiments, which also showed that the expression levels of genes involved in proteolytic activities and volatile trimethylamine production were also decreased.

CONCLUSION

Phenolic compounds can be used as potential food additives for preventing quality deterioration of fish products. © 2023 Society of Chemical Industry.