scholarly journals Characterization of the biofilm matrix composition of psychrotrophic, meat spoilage pseudomonads

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Nirmani N. Wickramasinghe ◽  
Mya M. Hlaing ◽  
Joshua T. Ravensdale ◽  
Ranil Coorey ◽  
P. Scott Chandry ◽  
...  
Keyword(s):  
Matrix Composition ◽  
Economic Losses ◽  
Limited Information ◽  
Pseudomonas Fragi ◽  
Meat Spoilage ◽  
Spoilage Bacteria ◽  
The Matrix ◽  
Total Carbohydrates ◽  
Cellular Dna ◽  
Cellulose Membranes

Abstract Psychrotrophic Pseudomonas species are the key spoilage bacteria of aerobically stored chilled meat. These organisms readily form biofilms on meat under refrigerated conditions leading to consumer rejection and associated economic losses. Limited information is available on the matrix composition of the biofilms formed by these bacteria. We quantified and characterized the main components of the matrix of mono-species biofilms of selected Pseudomonas fragi and Pseudomonas lundensis strains using chemical analysis and Raman spectroscopy. The biofilms were grown at 10 °C and 25 °C on nitro-cellulose membranes placed on surface sterilized beef cuts. Extra-cellular polymeric substances of the matrix were extracted in soluble and bound forms and were chemically assessed for total carbohydrates, proteins and extra-cellular DNA. Both Pseudomonas species showed a significant increase in total carbohydrates and total proteins when grown at 10 °C as compared to 25 °C. Extra-cellular DNA did not show a strong correlation with growth temperature. Raman spectra were obtained from planktonic bacteria and membrane grown biofilms at 10 °C and 25 °C. Higher levels of guanine were detected in planktonic cells as compared to biofilm cells. This study suggests that psychrotrophic Pseudomonas species may respond to cold stress by increasing extra-cellular polymer secretions.

scholarly journals Strain-Level Diversity Analysis of Pseudomonas fragi after In Situ Pangenome Reconstruction Shows Distinctive Spoilage-Associated Metabolic Traits Clearly Selected by Different Storage Conditions

2018 ◽  
Vol 85 (1) ◽  
Author(s):  
Francesca De Filippis ◽  
Antonietta La Storia ◽  
Francesco Villani ◽  
Danilo Ercolini
Keyword(s):  
Microbial Ecology ◽  
Strain Level ◽  
Economic Losses ◽  
Refrigerated Storage ◽  
Specific Storage ◽  
Pseudomonas Fragi ◽  
Content Type ◽  
Raw Meat ◽  
Meat Spoilage

ABSTRACT Microbial spoilage of raw meat causes huge economic losses every year. An understanding of the microbial ecology associated with the spoilage and its dynamics during the refrigerated storage of meat can help in preventing and delaying the spoilage-related activities. The raw meat microbiota is usually complex, but only a few members will develop during storage and cause spoilage upon the pressure from several external factors, such as temperature and oxygen availability. We characterized the metagenome of beef packed aerobically or under vacuum during refrigerated storage to explore how different packaging conditions may influence the microbial composition and potential spoilage-associated activities. Different population dynamics and spoilage-associated genomic repertoires occurred in beef stored aerobically or in vacuum packaging. Moreover, the pangenomes of Pseudomonas fragi strains were extracted from metagenomes. We demonstrated the presence of specific, storage-driven strain-level profiles of Pseudomonas fragi, characterized by different gene repertoires and thus potentially able to act differently during meat spoilage. The results provide new knowledge on strain-level microbial ecology associated with meat spoilage and may be of value for future strategies of spoilage prevention and food waste reduction. IMPORTANCE This work provides insights on the mechanisms involved in raw beef spoilage during refrigerated storage and on the selective pressure exerted by the packaging conditions. We highlighted the presence of different microbial metagenomes during the spoilage of beef packaged aerobically or under vacuum. The packaging condition was able to select specific Pseudomonas fragi strains with distinctive genomic repertoires. This study may help in deciphering the behavior of different biomes directly in situ in food and in understanding the specific contribution of different strains to food spoilage.

scholarly journals Antibacterial Metabolites obtained from fermentation of peanut and cowpea by Lactobacillus spp

2020 ◽  
Vol 24 (10) ◽  
pp. 1827-1834
Author(s):  
P.O. Oyedoh ◽  
C.E. Oshoma ◽  
M.J. Ikenebumeh
Keyword(s):  
Antibacterial Activity ◽  
Proteolytic Activity ◽  
Peanut Flour ◽  
Food Matrix ◽  
Peptide Concentration ◽  
Meat Spoilage ◽  
Spoilage Bacteria ◽  
The Matrix ◽  
Metabolites Production ◽  
Lactobacillus Spp

Lactic acid bacteria elective habitat is food matrix, where they release encrypted metabolites from several parent proteins as a result of their proteolytic activity in the matrix. These metabolites when decrypted confer different bioactive activity thus improving public health. This study was aimed at producing peptide containing metabolites with antibacterial efficacy from defatted cowpea and peanut using Lactobacillus spp. Lactobacillus spp. isolated from spoilt yoghurt were identified using culture dependent and independent method. The isolates were screened for proteolytic ability on skimmed milk agar. The selected isolate with highest proteolytic activity was used for metabolites production through fermentation of defatted cowpea and peanut at 37 oC for 72 h. Parameters analyzed during fermentation were pH, Lactobacillus count, protease activity, peptide concentration and antibacterial activity. The crude peptides produced were assayed for antibacterial activity against bacteria isolated from spoilt meat. From the identified Lactobacillus spp., L. plantarum CAU4347 had the highest proteolytic activity with clear zone of 24.50 ± 0.707 mm. During fermentation the highest and lowest Lactobacillus counts were from cowpea and peanut media with values 294.2 ± 0.21 ×107 and 0.60 ± 0.4 ×107 cfu/ml respectively. Cowpea medium inoculated with L. plantarum CAU4347, had the highest peptide concentration of 79.92 ± 0.01 µg/ml. Consequently, peanut medium showed higher antibacterial activity of 18 mm against Escherichia coli. This result finding suggests that encrypted peptide metabolites from cowpea and peanut flour can confer antibacterial activity against meat spoilage bacteria thus could be utilized as a potential bio-preservative. Keywords: Metabolites, Cowpea, Peanut, Bioactive, Fermentation, Lactobacillus plantarum

Detection of Meat Spoilage Bacteria by Using the Polymerase Chain Reaction

1996 ◽  
Vol 59 (8) ◽  
pp. 845-848 ◽  
Author(s):  
K. S. VENKITANARAYANAN ◽  
M. I. KHAN ◽  
C. FAUSTMAN ◽  
B. W. BERRY
Keyword(s):  
Polymerase Chain Reaction ◽  
Sequence Data ◽  
Economic Losses ◽  
Meat Industry ◽  
Dot Blot ◽  
Chain Reaction ◽  
Meat Spoilage ◽  
Spoilage Bacteria ◽  
Polymerase Chain ◽  
Dot Blot Analysis

The growth of spoilage bacteria results in a shorter shelf life of meat, causing economic losses to the meat industry. Based on 23S rDNA sequence data of Pseudomonas aeruginosa, two primers designated as PF (23 bases) and PR (20 bases) were synthesized for use in the polymerase chain reaction. A unique 207-base-pair DNA product from nine different bacteria typically associated with meat spoilage was amplified by the primers. Dot blot analysis with the internal DNA probe specific for the amplified products confirmed that the amplified DNA sequence is specific for the spoilage bacteria studied.

Precipitation of highly luminescent phases from PECVD Si suboxides

2004 ◽  
Vol 832 ◽  
Author(s):  
M. Perálvarez ◽  
M. López ◽  
B. Garrido ◽  
J.R. Morante ◽  
J. Barreto ◽  
...  
Keyword(s):  
Refractive Index ◽  
Phase Separation ◽  
Ion Implantation ◽  
Composition Profile ◽  
Matrix Composition ◽  
Light Sources ◽  
The Matrix ◽  
Detailed Composition ◽  
Preparation Route

ABSTRACTSi nanoclusters (Si-nc) embedded in SiO2 present outstanding luminescent emission in the visible and are the material of choice for the realization of efficient light sources integrated with Si technology. PECVD is an attractive preparation route but there is still the need to understand how Si excess and matrix composition affect the precipitation of Si-nc and their photoluminescence (PL) efficiency. The SiOx PECVD layers studied here have a Si excess up to 50% and a thickness between 50 and 100 nm. The phase separation, precipitation and growth of the Si-nc have been achieved by annealing at 1250 °C. For reference, the same study has been performed in Si-nc/SiO2 materials synthesized by ion implantation and annealing. Refractive index and thickness measured by ellipsometry show a densification of the layers after the H release during annealing. A detailed composition profile has been determined by XPS and FTIR analyses and shows almost complete phase separation except for the interfaces, where a depletion of Si-nc is found. EFTEM demonstrates that isolated Si-nc are formed for Si excess up to 25% while for higher Si excess a continuous Si phase is observed. The PL efficiency in PECVD samples is maximized for a Si excess of 17% which is the same Si excess than that for the most emitting implanted samples. No dependence of PL efficiency has been found on the presence of Nitrogen in the matrix (up to the 10%).

Slurry Wear Test of Long Kenaf Polyester Composite (LKPC) and Long Kenaf Polyester with Fiberglass Composite

2013 ◽  
Vol 393 ◽  
pp. 919-924
Author(s):  
Muhd Azimin Ab Ghani ◽  
A.F. Ahmad Kamal ◽  
Mohamad Ali Ahmad ◽  
Y.M.D. Taib ◽  
Z. Salleh ◽  
...  
Keyword(s):  
Sea Water ◽  
Wear Test ◽  
Matrix Composition ◽  
Slurry Erosion ◽  
Composite Surface ◽  
Wear And Friction ◽  
Fiberglass Composite ◽  
The Matrix ◽  
Polyester Composite ◽  
Erosion Test

This paper presents an experimental study on the influence of fiberglass woven in Long Kenaf Polyester Composite (LKPC). Wear and friction characteristics were examined using sea water and sand as a slurry. Wear test were carried out using Slurry Erosion Test Rig (TR-40). These tests were performed at room temperature with speed of 200 rpm for every 2 km interval. The results from the tests show that mass loss were depends on the matrix composition of the composite. Surface Roughness, Ra, was consistently reduced after each test in all cases.

Influence of WC Particle Size and Matrix Composition on the Behavior of WC-Co-Cr Coatings Sprayed by the HVOF Process

1997 ◽  
Author(s):  
J. Berget ◽  
E. Bardal ◽  
T. Rogne
Keyword(s):  
Particle Size ◽  
Wear Resistance ◽  
Corrosion Resistance ◽  
Chromium Content ◽  
Deposition Efficiency ◽  
Matrix Composition ◽  
Coating Properties ◽  
Hvof Process ◽  
Erosion Corrosion ◽  
The Matrix

Abstract WC-Co-Cr powders with different WC particle size have been sprayed by the HVOF process. At constant spraying conditions the powders give coatings of different quality. The deposition efficiency during spraying of powders containing large WC particles was found to be low compared to powders with finer WC grains. In addition the amounts of porosity and cracks were different. The coatings have been characterised by different methods. Erosion and erosion-corrosion tests showed that the WC particle size also influence the wear resistance of the coatings. Small WC particle size was found to be beneficial. Chemical composition of the matrix was also found to be decisive for the coating properties. An increase of the chromium content improved the erosion-corrosion resistance.

scholarly journals The Impact of Maltodextrin and Inulin on the Protection of Natural Antioxidants in Powders Made of Saskatoon Berry Fruit, Juice, and Pomace as Functional Food Ingredients

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1805 ◽  
Author(s):  
Sabina Lachowicz ◽  
Anna Michalska-Ciechanowska ◽  
Jan Oszmiański
Keyword(s):  
Fruit Juice ◽  
Radical Scavenging ◽  
Antioxidant Potential ◽  
Matrix Composition ◽  
Vacuum Drying ◽  
Frap Assay ◽  
Food Ingredients ◽  
The Matrix ◽  
Fruit Powder ◽  
The Impact

The objective of this study was to examine the effect of inulin and maltodextrin applied during vacuum drying of Saskatoon berry fruit, juice, and pomace on the retention of bioactive compounds and antioxidant capacity (radical scavenging capacity (ABTS), ferric reducing antioxidant potential (FRAP)) of powders obtained. Ultra-high performance liquid chromatography (UPLC-PDA-ESI-MS/MS) was used to identify major groups of polyphenolic compounds, such as: flavan-3-ols (35% of all polyphenols for fruit powder, 33% for juice powder, and 39% for pomace powders of all polyphenols), anthocyanins (26% for fruit powder, 5% for juice powder, and 34% for pomace), phenolic acids (33% for fruit powder, 55% for juice powder, and 20% for pomace powder), and flavanols (6% for fruit powder, 6% for juice powder, and 7% for pomace powder). In general, the content of polyphenols was more dependent on the content than on the type of carrier used for drying, regardless of the matrix tested. The average sum of polyphenols and the antioxidant activity (for ABTS and FRAP assay) of the powders with 30% of carrier addition were 5054.2 mg/100 g dry matter (d.m.) as well as 5.3 and 3.6 mmol Trolox/100 g d.m. in the ABTS and FRAP tests, respectively. The increase in carrier concentration by 20% caused a decrease of 1.5-fold in the content of polyphenols and a 1.6-fold and 1.5-fold in the antioxidant potential, regardless of the matrix tested. The principal component analysis (PCA) analysis indicated that the freeze-drying process led to the lowest degradation of the identified compounds, regardless of the matrix tested, with the exception of juice and pomace powders dried by vacuum drying at 60 °C. In this case, the release of (−)-epicatechin was observed, causing an increase in the flavanol contents. Thus, this work demonstrated the effect of processing and matrix composition on the preservation of antioxidant bioactives in Saskatoon berry powders. Properly designed high-quality Saskatoon berry powders with the mentioned carriers may be used as nutraceutical additives to fortify food products and to improve their functional properties.

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