SpoilagePseudomonasbiofilm withEscherichia coliprotection in fish meat at 5 °C

Abstract

BACKGROUND Pseudomonas are part of the indigenous microbiota of different foods, where they gradually cause spoilage. In fish meat, Pseudomonas fragi and Pseudomonas psychrophila have been identified as important spoilers. The initial aim of this study was to investigate the physiological characteristics, adhesion, and biofilm of P. fragi and P. psychrophila under temperatures related to the fish‐processing industry. The further aim was to define the problem of increased growth of pathogenic bacteria in the presence of spoilage bacteria in vitro and in fish meat. RESULTS Temperature dependence on physiological characteristics, adhesion, and biofilm was observed. Hydrophobicity and autoaggregation were most prominent at 15 °C, and at this temperature floating biofilm was also formed. The adhesion of these Pseudomonas was up to 2 log CFU cm−1 more pronounced on stainless steel than polystyrene, with up to five times greater biofilm biomass production at 5 °C on polystyrene. This paralleled at least a 0.5 log CFU g−1 increase in the pathogenic bacterium Escherichia coli in fish meat. CONCLUSION Pseudomonas fragi and P. psychrophila adhesion and biofilm depend on the temperature, and are stimulated by temperatures that can occur during the processing and storage of fish meat. Strong Pseudomonas biofilm formation under refrigeration conditions is protective for E. coli, potentially by providing more favorable conditions by ensuring a higher concentration of nutrients. Interactions between spoilage Pseudomonas and pathogenic bacteria can occur through different mechanisms, and an understanding of these is of particular importance to ensure the overall quality and safety of fish meat and other proteinaceous foods. © 2019 Society of Chemical Industry

Combination of rosemary extract and buffered vinegar inhibits Pseudomonas and Shewanella growth in common carp (Cyprinus carpio)

“…Despite commonly reported improved antimicrobial activity at low temperatures, it was found that for Pseudomonas cold temperature can even increase its resistance to antimicrobials . Therefore, it is assumed that this difference was not seen due to the marked psychrotrophic nature of these bacteria …”

“…Taking into account good hygienic practice and integration of additional processing steps, microbiological quality of common carp meat can be improved . Pseudomonas and Shewanella are two important spoilage microorganisms in common carp, which are resistant or poorly sensitive to natural additives used in in vitro antimicrobial studies, or applied to various foods . In our study, we evaluated both genera in vitro and in situ in terms of reducing their growth and spoilage potential by adding rosemary extract, buffered vinegar and their combination.…”

“…The bacteria were stored at −80 °C in tryptic soy broth (Biolife, Milan, Italy) with 15% glycerol (Kemika, Zagreb, Croatia), revitalized on tryptic soy agar (Biolife, Milan, Italy) and incubated at 30 °C for 24 h. Standardized inocula were further prepared in broth or food model by diluting cultures to reach a final concentration of 5.2–5.6 log CFU mL −1 or 3.2–3.6 log CFU mL −1 . Food model was prepared as described previously . In short, common carp was bought at a local market, cleaned, deboned and deskinned, and the meat was chopped in a kitchen blender (Studio, Hans‐Ulrich Petermann, Seefeld, Germany) and homogenized (Stomacher400, Seward, Worthing, UK).…”

“…In fresh fish meat during aerobic refrigeration storage, bacteria from genera Pseudomonas and Shewanella are the commonly occurring spoilage microbiota, which often prevail during storage, starting from initially more diverse microbiota . Pseudomonas and Shewanella have been identified also in spoiled common carp meat . These bacteria predominate as ubiquitous psychrotrophs with simple nutritional requirements .…”

Understanding spoilage microbial community and spoilage mechanisms in foods of animal origin

“…In recent years, molecular methods have contributed a lot to an incomplete phenotypic description of important groups of freshwater fish spoilage bacteria (Zhang, Li, Li, Liu, & Luo, 2015). Furthermore, knowledge about spoilage prevention by the steps of fish processing (Sterniša et al, 2016;Sterniša et al, 2018), microbial interactions (Sterniša, Klančnik, & Smole Možina, 2019) and/or new packaging materials and processes has improved a lot in recent years (Yu et al, 2019;Yu, Li, Xu, Jiang, & Xia, 2017). However, not all the preservation and packaging methods have been evaluated for freshwater fish (Sterniša et al, 2016).…”