Biofilm formation in food processing environment and within equipment increases the risk of product spoilage and contamination with pathogens. Cleaning-in-place (CIP) operations are useful in ...removing soils and in sanitizing processing equipment, including eliminating biofilms. However, CIP is a resource-intensive process, particularly in the usage of chemical detergents, heat, and sanitizers. The current study was initiated to investigate the feasibility of integrating ozone into CIP operations to facilitate the elimination of
biofilm, with the long-term goal of decreasing the dependance on conventional cleaning and sanitizing reagents. To investigate integrating ozone into CIP, a robust biofilm of
was developed on a pilot-scale food processing equipment after 2 days of incubation in 10% skim milk (skim milk-water mixture, 1:9 v/v) under stagnant conditions, followed by additional 5 days of circulation while feeding 10% fresh skim milk. CIP was applied using water prerinse at 22-25°C, alkaline cleaning with 0.2% potassium hydroxide at 50°C, and a final water rinse. These CIP operations reduced planktonic cell populations below the detection method's limit but did not fully remove
biofilm from either smooth or rough surfaces of the processing equipment. When the CIP process was followed by application of an aqueous ozone step (10 ppm for 10 min), the treatment reduced biofilm cell population, on smooth and rough surfaces, below the recovery method's detection limit (0.9 and 1.4 log CFU/ 100 cm
, respectively). These findings demonstrate the utility of ozone-assisted CIP in eliminating microbial biofilms on processing equipment, but further research is needed to optimize the use of cleaning agents and the application of ozone.
The ability to inactivate Pseudomonas spp. and Rhodotorula mucilaginosa by a photocatalyst thin film, obtained via a combination of anatase and rutile titanium dioxide incorporation into a low ...density polyethylene (LDPE) polymeric matrix by a melt blending method, was addressed in this study. The number of surviving cell of the Pseudomonas spp. was decreased by 4 log CFU/ml and 1.35 log CFU/ml after 3 h of UVA illumination on TiO2 nanocomposite thin film and LDPE thin film, respectively. The number of cells of R. mucilaginosa decreased by 2 log CFU/ml and 0.64 log CFU/ml on TiO2 nanocomposite thin film and LDPE thin film, respectively. In an in vivo test carried out on fresh pears packaged in TiO2 nanocomposite film and stored under illumination by a fluorescent light lamp at 5 °C for 17 days, the number of mesophilic bacteria and yeast cells decreased significantly compared to samples stored in LDPE film. The greatest effects were recorded by combining UVA illumination and active film. It was also proven that the photocatalyst thin film prepared by extrusion could be effectively used in fruit packaging applications.
► A new TiO2 nanocomposite film was studied for microorganism disinfection. ► Pseudomonas spp. and Rhodotorula mucilaginosa were addressed in this study. ► The survival of Pseudomonas spp. decreased by 4 log CFU/mL under UVA on nano film. ► The survival density decreased 2 log CFU/ml for R. mucilaginosa. ► Microorganisms decreased significantly on pear in nano film under fluorescent lamp.
This paper demonstrates the application of surface-enhanced Raman scattering (SERS) using positive charged gold nanorods (Au NRs) as an enhancement substrate to classify Pseudomonas spp. coupled with ...multivariate methods. Four species of Pseudomonas as dominant spoilage bacteria of food were isolated from rotten chicken, namely, Pseudomonas gessardii (P9), Pseudomonas psychrophila (P8), Pseudomonas psychrophila (S2) and Pseudomonas fluorescens (T3). Au NRs were synthesized with positive charge by seed-mediated growth method which can be adsorbed onto the surface of the bacteria by electrostatic adsorption. SERS spectra were collected individually for four types of Pseudomonas and pretreated by mean centering (MC), then principal component analysis (PCA) and hierarchical clustering analysis (LDA) were used to achieve data dimensionality reduction and visualize the result of differentiation for the species of Pseudomonas. Particularly, the classification accuracy of LDA was reached to 100%. Following we applied hierarchical clustering analysis (HCA) to cluster each species of Pseudomonas and the results of HCA consistent with the results of 16S rRNA. This study has shown that SERS combined with LDA and HCA can be used as a reliable method to classify Pseudomonas.
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•Four kinds of Pseudomonas strains were screened from spoilage chicken.•Gram negative bacteria can electrostatically adsorbed with positively charged Au NRs.•SERS combined with LDA can correctly classify four kinds of Pseudomonas species.•The result of SERS combined with HCA was consistent with the result of 16S rRNA.
Octylphenol polyethoxylate (OPEO) surfactants are widely used as commercial cleaning products and agricultural pesticides. Sewage effluents containing high levels of OPEOs are often discharged into ...soil–slurry systems. OPEOs have been identified as endocrine-disrupting compounds and are a threat to organisms present in ecological systems. Several studies have previously investigated methods to degrade OPEOs; however, clarifications regarding the impact on environmental ecology and bacterial physiological changes are required. This study aimed to evaluate the changes in bacterial community and physiological characteristics that occur during OPEO biodegradation in terms of abiotic factors. The results show that adsorption of OPEO on soil can be described using the Freundlich adsorption isotherm. The rates of OPEO biodegradation in different environmental matrices were compared and the results are as follows: aqueous system > clay–slurry system > natural soil–slurry system, all of which can be identified by their distinct community-level physiological profiles (CLPPs). OPEO biodegradation is always faster in the monomer state than in the micelle state. Bacterial numbers are maintained at high level and range from 107 to 108 CFU/mL; Pseudomonas spp. is dominant and likely plays an important role in OPEO biodegradation. Fluctuations in the utilisation of carboxylic acid groups were found. The enzymatic activity of esterases was significant, ranging from 12.5–54.1%. Phosphatase activity in the soil slurries ranged from 2.1–45.8%. The responses in terms of physiological characteristics indicate the soil ecology state during OPEO biodegradation.
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•Effective OPEO biodegradation by an indigenous mixed bacterial culture.•The influence of abiotic factors on OPEO biodegradation was evaluated.•The dominant Pseudomonas spp. plays an important role in OPEO biodegradation.•Excellent ecological indicators of carboxylic acid and esterase during degradation.
•Edible coatings with pomegranate peel extract (PPE) were tested against P. putida.•The most effective coating-PPE combination was applied on fresh peeled shrimps.•Chitosan at all PPE concentrations ...showed antibacterial activity in vitro.•Chitosan with PPE reduced Pseudomonas spp. and psycrotrophic bacteria in shrimps.•Chitosan with PPE effectively reduced the production of volatile bases after 6 d.
The present study aimed at assessing the potential of edible coatings based on chitosan (Ch) and locust bean gum (LBG) incorporating pomegranate peel extract (PPE) to maintain quality of shrimps during cold storage. Firstly, the study evaluated different PPE concentrations applied to Ch and LBG against Pseudomonas putida in vitro. Then, in vivo trials were carried out on headed and peeled shrimps coated with Ch and LBG incorporating the most effective PPE level, to evaluate the effect during storage of different coatings on Pseudomonas spp., total psychrotrophic bacteria counts, total volatile basic nitrogen (TVB-N) and visual color as quality indexes. Results proved the effective synergy of PPE with Ch at reducing microbial spoilage during storage: indeed, Ch incorporating PPE was able to reduce the Pseudomonas spp. count by about 2 log units and to maintain the psychrotrophic microbial load below 7 CFU/g for 6 days. In addition, after 6 days, TVB-N levels in shrimps coated with Ch incorporating PPE were as low as the values recorded in the control samples after 2 days.
The progressive ability of a six-strains L. monocytogenes cocktail to form biofilm on stainless steel (SS), under fish-processing simulated conditions, was investigated, together with the biocide ...tolerance of the developed sessile communities. To do this, the pathogenic bacteria were left to form biofilms on SS coupons incubated at 15°C, for up to 240h, in periodically renewable model fish juice substrate, prepared by aquatic extraction of sea bream flesh, under both mono-species and mixed-culture conditions. In the latter case, L. monocytogenes cells were left to produce biofilms together with either a five-strains cocktail of four Pseudomonas species (fragi, savastanoi, putida and fluorescens), or whole fish indigenous microflora. The biofilm populations of L. monocytogenes, Pseudomonas spp., Enterobacteriaceae, H2S producing and aerobic plate count (APC) bacteria, both before and after disinfection, were enumerated by selective agar plating, following their removal from surfaces through bead vortexing. Scanning electron microscopy was also applied to monitor biofilm formation dynamics and anti-biofilm biocidal actions. Results revealed the clear dominance of Pseudomonas spp. bacteria in all the mixed-culture sessile communities throughout the whole incubation period, with the in parallel sole presence of L. monocytogenes cells to further increase (ca. 10-fold) their sessile growth. With respect to L. monocytogenes and under mono-species conditions, its maximum biofilm population (ca. 6logCFU/cm2) was reached at 192h of incubation, whereas when solely Pseudomonas spp. cells were also present, its biofilm formation was either slightly hindered or favored, depending on the incubation day. However, when all the fish indigenous microflora was present, biofilm formation by the pathogen was greatly hampered and never exceeded 3logCFU/cm2, while under the same conditions, APC biofilm counts had already surpassed 7logCFU/cm2 by the end of the first 96h of incubation. All here tested disinfection treatments, composed of two common food industry biocides gradually applied for 15 to 30min, were insufficient against L. monocytogenes mono-species biofilm communities, with the resistance of the latter to significantly increase from the 3rd to 7th day of incubation. However, all these treatments resulted in no detectable L. monocytogenes cells upon their application against the mixed-culture sessile communities also containing the fish indigenous microflora, something probably associated with the low attached population level of these pathogenic cells before disinfection (<102CFU/cm2) under such mixed-culture conditions. Taken together, all these results expand our knowledge on both the population dynamics and resistance of L. monocytogenes biofilm cells under conditions resembling those encountered within the seafood industry and should be considered upon designing and applying effective anti-biofilm strategies.
•Pseudomonas spp. dominated in mixed-culture biofilms throughout whole incubation.•Pseudomonas's presence either hindered or favored L. monocytogenes biofilm growth.•Biofilm growth by fish endemic bacterial flora reached 7logCFU/cm2 in 4d.•Fish indigenous microflora greatly hampered L. monocytogenes biofilm formation.•Food industry biocides did not eliminate L. monocytogenes mono-species biofilms.
Drought is one of the major abiotic stresses affecting yield of dryland crops. Rhizobacterial populations of stressed soils are adapted and tolerant to stress and can be screened for isolation of ...efficient stress adaptive/tolerant, plant growth promoting rhizobacterial (PGPR) strains that can be used as inoculants for crops grown in stressed ecosystems. The effect of inoculation of five drought tolerant plant growth promoting Pseudomonas spp. strains namely P. entomophila strain BV-P13, P. stutzeri strain GRFHAP-P14, P. putida strain GAP-P45, P. syringae strain GRFHYTP52, and P. monteilli strain WAPP53 on growth, osmoregulation and antioxidant status of maize seedlings under drought stress conditions was investigated. Drought stress induced by withholding irrigation had drastic effects on growth of maize seedlings. However seed bacterization of maize with Pseudomonas spp. strains improved plant biomass, relative water content, leaf water potential, root adhering soil/root tissue ratio, aggregate stability and mean weight diameter and decreased leaf water loss. The inoculated plants showed higher levels of proline, sugars, free amino acids under drought stress. However protein and starch content was reduced under drought stress conditions. Inoculation decreased electrolyte leakage compared to uninoculated seedlings under drought stress. As compared to uninoculated seedlings, inoculated seedlings showed significantly lower activities of antioxidant enzymes, ascorbate peroxidase (APX), catalase (CAT), glutathione peroxidase (GPX) under drought stress, indicating that inoculated seedlings felt less stress as compared to uninoculated seedlings. The strain GAP-P45 was found to be the best in terms of influencing growth and biochemical and physiological status of the seedlings under drought stress. The study reports the potential of rhizobacteria in alleviating drought stress effects in maize.
Cefiderocol is a novel cephalosporin–siderophore conjugate antibiotic that holds promise to thwart infections caused by multi-drug-resistant gram-negative bacilli. Its antibacterial activity against ...normally susceptible species is not affected by most β-lactamases, including metallo-β-lactamases. Due to the siderophore-mediated entry into the cell, the activity of cefiderocol is less affected by porin loss or active efflux resistance than many other β-lactam antibiotics. The aim of this study was to assess in vitro susceptibility to the cefiderocol of carbapenemase-producing gram-negative bacilli from clinical samples of hospitalized patients.
We analyzed 102 clinical strains of carbapenemase-producing Enterobacterales and non-fermentives from hospital centers in Łódź, Poland. Antimicrobial susceptibility to cefiderocol was tested by the minimum inhibitory concentration test strips and disc diffusion methods.
The obtained results turned out to be ambiguous, and the area of technical uncertainty made their interpretation very difficult.
The cost of therapy with this antibiotic, and difficulties in interpreting the drug susceptibility are the limitations to the use of cefiderocol. Intensive work should be carried out to finally standardize an easily accessible and reliable method for the determination of susceptibility to cefiderocol.
Pythium myriotylum
is a notorious soil-borne oomycete that causes post-emergence damping-off in chili pepper. Of various disease management strategies, utilization of plant growth promoting ...rhizobacteria (PGPR) in disease suppression and plant growth promotion is an interesting strategy. The present study was performed to isolate and characterize PGPR indigenous to the chili rhizosphere in Pakistan, and to test the potential to suppress the damping-off and plant growth promotion in chili. Out of a total of 28 antagonists, eight bacterial isolates (4a2, JHL-8, JHL-12, 1C2, RH-24, 1D, 5C, and RH-87) significantly suppressed the colony growth of
P. myriotylum
in a dual culture experiment. All the tested bacterial isolates were characterized for biochemical attributes, and 16S rRNA sequence based phylogenetic analysis identified these isolates as
Flavobacterium
spp.,
Bacillus megaterium
,
Pseudomonas putida
,
Bacillus cereus
, and
Pseudomonas libanensis
. All the tested bacterial isolates showed positive test results for ammonia production, starch hydrolase (except 4a2), and hydrogen cyanide production (except 4a2 and 1D). All the tested antagonists produced indole-3-acetic acid (13.4–39.0 μg mL
–1
), solubilized inorganic phosphate (75–103 μg mL
–1
), and produced siderophores (17.1–23.7%)
in vitro
. All the tested bacterial isolates showed varying levels of susceptibility and resistance response against different antibiotics and all these bacterial isolates were found to be non-pathogenic to chili seeds and notably enhanced percentage seed germination, plumule, redical length, and vigor index over un-inoculated control. Additionally, under pathogen pressure, bacterization increased the defense related enzymes such as Peroxidase (PO), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL) activates. Moreover, the treatment of chili seeds with these bacterial isolates significantly suppressed the damping-off caused by
P. myriotylum
and improved PGP traits compared to the control. In addition, a positive correlation was noticed between shoot, root length, and dry shoot and root weight, and there was a negative correlation between dry shoot, root weight, and seedling percentage mortality. These results showed that native PGPR possesses multiple traits beneficial to the chili plants and can be used to develop eco-friendly and effective seed treatment formulation as an alternative to synthetic chemical fungicides.
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