Sixty-six putative Pseudomonas strains isolated from different food matrices (ready-to-eat vegetables, meat, milk and dairy products) were examined for their phenotypic features and enzymatic ...spoilage activities. Their genotype was studied by BOX-PCR, Pseudomonas specific 16S PCR, aprX and housekeeping genes sequencing (16S rRNA gene, gyrB and rpoB). The majority of the isolates are very versatile as shown by their wide ranges in growth temperature (4–45 °C), pigment production and production of enzymes. The BOX-PCR clustering showed a high genetic diversity among the isolates and phylogenetic analysis of the rpoB gene allowed a first putative identification at the species level. Thirteen isolates were provisionally classified as Pseudomonas gessardii-like, but probably belong to a yet unknown Pseudomonas species in the Pseudomonas fluorescens group.
Protease-activity was qualitatively and quantitatively verified. A large variation in proteolytic activity measured in UHT-milk was observed amongst the protease positive isolates. Several isolates provisionally classified as P. gessardii-like showed the highest activities. An aprX gene based phylogenetic dendrogram showed five different groups and two sub-groups, for which a correlation with the matrix of origin could be demonstrated. An insertion of 15 bp was observed in the aprX gene sequences of isolates of mainly dairy origin.
•A large diversity of Pseudomonas species was found over the different food matrices.•All isolates were able to produce enzymes and/or pigments that can affect foods.•A perfect match was found between proteolytic activity and presence of aprX gene.
After cleaning and disinfection (C&D), surface contamination can still be present in the production environment of food companies. Microbiological contamination on cleaned surfaces can be transferred ...to the manufactured food and consequently lead to foodborne illness and early food spoilage. However, knowledge about the microbiological composition of residual contamination after C&D and the effect of this contamination on food spoilage is lacking in various food sectors. In this study, we identified the remaining dominant microbiota on food contact surfaces after C&D in seven food companies and assessed the spoilage potential of the microbiota under laboratory conditions. The dominant microbiota on surfaces contaminated at ≥10
CFU/100 cm
after C&D was identified based on 16S rRNA sequences. The ability of these microorganisms to hydrolyze proteins, lipids, and phospholipids, ferment glucose and lactose, produce hydrogen sulfide, and degrade starch and gelatin also was evaluated. Genera that were most abundant among the dominant microbiota on food contact surfaces after C&D were Pseudomonas, Microbacterium, Stenotrophomonas, Staphylococcus, and Streptococcus. Pseudomonas spp. were identified in five of the participating food companies, and 86.8% of the isolates evaluated had spoilage potential in the laboratory tests. Microbacterium and Stenotrophomonas spp. were identified in five and six of the food companies, respectively, and all tested isolates had spoilage potential. This information will be useful for food companies in their quest to characterize surface contamination after C&D, to identify causes of microbiological food contamination and spoilage, and to determine the need for more thorough C&D.
This study was performed to develop a predictive growth model of Pseudomonas spp. to ensure the safety of fresh duck breast. Sterile fresh duck breasts were inoculated with Pseudomonas spp. and ...stored at 4°C, 10°C, 15°C, 20°C, 25°C, and 30°C to measure the microbial change. The Baranyi primary model was used to simulate the growth changes of Pseudomonas spp. at different temperatures. The square root type model and hyperbolic function as secondary models were used to model the effect of temperature on the maximum specific growth rate and lag phase duration. The results showed that the primary models fitted the growth data well (all R2 > 0.900 and RMSE were close to 0). In validation study of secondary model, R2 were 0.987 and 0.925, RMSE were 0.017 and 1.825, respectively, indicating that the parameters of primary models were accurately predicted by secondary models. The validation experiments at tested temperatures proved that the changes of Pseudomonas spp. could be predicted accurately by the developed models combining primary and secondary models both at constant and variable temperatures. The model could be applied to predict the growth of Pseudomonas spp. in logistics for avoiding microbial spoilage on fresh duck breast.
Antimicrobial resistance is an important global issue that impacts the efficacy of established antimicrobial therapy. This is true globally and within the Arab countries of the Middle East, where a ...range of key Gram-negative pathogens pose challenges to effective therapy. There is a need to establish effective treatment recommendations for this region given specific challenges to antimicrobial therapy, including variations in the availability of antimicrobials, infrastructure and specialist expertise. This consensus provides regional recommendations for the first-line treatment of hospitalized patients with serious infections caused by World Health Organization critical priority Gram-negative pathogens Acinetobacter baumannii and Pseudomonas aeruginosa resistant to carbapenems, and Enterobacteriaceae resistant to carbapenems and third-generation cephalosporins. A working group comprising experts in infectious disease across the region was assembled to review contemporary literature and provide additional consensus on the treatment of key pathogens. Detailed therapeutic recommendations are formulated for these pathogens with a focus on bacteraemia, nosocomial pneumonia, urinary tract infections, skin and soft tissue infections, and intra-abdominal infections. First-line treatment options are provided, along with alternative agents that may be used where variations in antimicrobial availability exist or where local preferences and resistance patterns should be considered. These recommendations take into consideration the diverse social and healthcare structures of the Arab countries of the Middle East, meeting a need that is not filled by international guidelines. There is a need for these recommendations to be updated continually to reflect changes in antimicrobial resistance in the region, as well as drug availability and emerging data from clinical trials.
The growth of naturally contaminated pseudomonads on fresh breast and thigh poultry fillets during aerobic storage was studied and modeled as a function of temperature (0–30°C). A statistical ...comparison of the models for breast and thigh fillets showed that muscle type does not significantly affect the temperature dependence of pseudomonads growth kinetics. A unified model for breast and thigh was developed and validated against pseudomonads growth rate data under isothermal conditions extracted from literature and experimental data under dynamic temperature conditions. The validation results showed a satisfactory performance of the model with the bias and accuracy factors ranging from 0.85 to 1.09 and 1.02 to 1.21, respectively. The model was further used to predict the shelf life of fresh poultry as the time required by pseudomonads to reach the spoilage level for various scenarios of temperature, initial contamination level, and physiological state of pseudomonads demonstrating its application in a risk-based shelf-life assessment of fresh poultry products.
The potential of phenazine-producing strains for the management of fungal and oomycete plant pathogens has been reviewed for the first time. Isolated natural phenazines showed similar, or even ...higher, antifungal activity in comparison with commercial fungicides. The occurrence and concentration of phenazines strongly depended on the studied strains and the antifungal activity of the strains was found to be dependent on the biosynthesis of phenazines. Except for phenazine-1-carboxylic acid (PCA), most phenazines were found in the secretions below their minimum inhibitory concentrations (MIC) and, in general, most strains showed low in vivo inhibitory activities, observing the highest biocontrol ability when using PCA-producing Pseudomonas chlororaphis and P. fluorescens. Most reports focused on the study of Pseudomonas, reducing the structural diversity, and limited the biocontrol screenings to root diseases. The conclusions achieved in this work help to understand the current state of the research field, and reveal new insights on the development of efficient biocontrol strategies using phenazine-producing strains.
Cronobacter and Pseudomonas spp. are pathogenic organisms that are associated with neonatal morbidities such as bacteremia, sepsis, necrotizing enterocolitis (NEC), and infant meningitis. Lactoferrin ...(Lf) is a known bactericidal component of fresh human milk. Infants receiving formula or pasteurized donor milk however may not be receiving lactoferrin at same concentration as mother's own milk, so it is beneficial to understand an exogenous role for dairy bovine lactoferrin (bLf). Our aim was to investigate the potential for bLf to provide a novel way to inhibit the growth of these harmful organisms in infant feeding. Subinhibitory doses, Disc-diffusion assay, Minimum Inhibitory Concentrations (MIC), Minimum Bactericidal Concentrations (MBC), and challenge experiments in powder formula were used to investigate the effects of bLf on sepsis-causing bacteria such as C. muytjensii (ATCC-51329), C. sakazakii (ATCC-12868), C. sakazakii (ATCC-9027), P. aeruginosa (ATCC-19429), and P. aeruginosa (ATCC-9027). MIC and MBC of bLf in the range of 12.5–31.25 μM were sufficient to achieve a 3 log reduction of Cronobacter in nutrient broth (P < 0.0001). Similarly, minimum concentrations of 43.75–118.75 μM bLf against Pseudomonas (P < 0.0001) were demonstrated. After bactericidal concentrations were determined, higher resistant strains such as C. sakazakii (ATCC-12868) and P. aeruginosa (ATCC-19429) were chosen as ideal candidates for the bLf supplementation challenge studies. The bLf reduced the C. sakazakii (ATCC-12868) by 3.3 log at 35 °C, 2.8 log at 23 °C, and 1.9 log at 4 °C (P < 0.0001), whereas P. aeruginosa (ATCC-19429) showed 2.4 log reduction at 35 °C, 2.8 log at 23 °C (P < 0.0001), and 1.8 log at 4 °C (P < 0.01). Results indicated that bLf could effectively inactivate the sepsis-causing organisms in reconstituted infant formula and in bacterial growth media. Fortification of infant formula with bLf may address the problems of spoilage/contamination issues and provide a safety measure for feeding infants without mother's own milk.
•Bovine lactoferrin can act as antibacterial agent in infant formula.•Bovine lactoferrin is bactericidal against Cronobacter and Pseudomonas strains.•Safety measure for feeding infants without mother's own milk.
The microbes in the rhizosphere (or mycorrhizosphere) could promote plant growth, however, it is unclear whether mycorrhizosphere microbes could fight multiple fungal pathogens. In this study, ...twenty-one bacterial strains distributed in 6 genera, including 5
Pseudomonas
strains, were isolated from mycorrhizal samples of
Polyporus umbellatus
that rely on other fungi during their life cycles. Further screening and pot experiments showed that the
Pseudomonas
strain ZL8 not only inhibited the growth of phytopathogenic fungi, but also promoted the growth of
Salvia miltiorrhiza
through inhibiting its wilting. In addition, strain ZL8 was found to have the ability to dissolve phosphate, produce IAA and siderophore. Nineteen compounds were identified from the fermentation broth of strain ZL8, of which 2,4-diacetylphloroglucinol (DAPG) had a significant inhibitory effect on phytopathogenic fungi with a minimum inhibitory concentration of 3.12–25 μg/mL. Molecular docking predicted that DAPG could bind to myosin I at two unique sites, which may be responsible to the inhibition of fungal growth. The evaluation results showed that strain ZL8 can be used to develop a dual-purpose biocontrol agents and biofertilizer. These results also provide new insights into the discovery and utilization of new resources for biocontrol agents and biolfertilizers.
Diazotrophic microorganisms are free-living groups of organisms that can convert atmospheric nitrogen (N) into bioavailable nitrogen for plants, which increases crop development and production. The ...purpose of the current study was to ascertain how diazotrophic plant growth promoting (PGP) Pseudomonas strains (P. koreensis CY4 and P. entomophila CN11) enhanced nitrogen fixation, defense activity, and PGP attributes of sugarcane varieties; GT11 and G×B9. A 15N isotope-dilution study was conducted to confirm the sugarcane strains' capacity to fix nitrogen, and the results indicated that between 21 to 35% of plant, nitrogen is fixed biologically by selected rhizobacteria. In comparison to the control, after 30, 60, and 90 days, both CY4 and CN11 strains significantly increased defense-related enzymes (catalase, peroxidase, phenylalanine ammonia-lyase, superoxide dismutase, glucanase, and chitinase) and phytohormones (abscisic acid, ABA, cytokinin, etc.) in GT11 and GXB. Additionally, the expression of SuCHI, SuGLU, SuCAT, SuSOD, and SuPAL genes was found to be elevated in Pseudomonas strains inoculated plants using real-time quantitative polymerase chain reaction (RT-qPCR). Both bacterial strains increased all physiological parameters and chlorophyll content in sugarcane plants more than their control. The effects of P. koreensis CY4 and P. entomophila CN11 strains on sugarcane growth promotion and nitrogen fixation under greenhouse conditions are described here for the first time systematically. The results of confirmation studies demonstrated that P. koreensis CY4 and P. entomophila are PGP bacterial strains with the potential to be employed as a biofertilizer for sugarcane growth, nitrogen nutrient absorption, and reduced application of chemical nitrogenous fertilizers in agricultural fields.
Background and Objective: Pseudomonas spp. are bacteria with the widest effects on food spoilage. These bacteria can be found in several environments such as soil and water. The major purpose of this ...study was to develop a software; by which, the growth behaviours of Pseudomonas spp. in culture media could be predicted. Material and Methods: A total number of 509 bacterial data points of Pseudomonas spp. in culture media were collected from the ComBase database. Temperature and pH were used as the major prediction variables for the description of Pseudomonas spp. behaviours in culture media. Modified Gompertz, Baranyi and Huang models, the most commonly used models in predictive food microbiology to predict the count of microorganisms, were used as well. Fitting capability of each model was assessed and compared with other capabilities considering their statistical indices of the root mean square error, RMSE; coefficient of determination, R2; corrected Akaike information criterion, AICc; and Bayesian information criterion, BIC. Results and Conclusion: Huang model provided better predictions with 0.951 of R2 and 0.825 of RMSE, compared to those of traditionally used models. Prediction capability of the Huang model was assessed considering externally collected data from the ComBase database. Huang model in the validation process provided satisfactory statistical indices (bias factor = 1.027 and accuracy factor = 1.075). These results have revealed that Huang model can be reliably used as a model of describing the growth behaviours of Pseudomonas spp. Furthermore, developed software in this study includes significant potentials for predicting Pseudomonas counts in culture media. Conflict of interest: The authors declare no conflict of interest.
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