A psychrotrophic Burkholderia cepacia strain isolated from refrigerated raw milk showing proteolytic activity and adhesion to stainless steel

2011 ◽  
Vol 78 (3) ◽  
pp. 257-262 ◽  
Author(s):  
Maria de Fátima Barros Leal Nörnberg ◽  
Marilene Lenz Mentges ◽  
Silvana Terra Silveira ◽  
Eduardo César Tondo ◽  
Adriano Brandelli
Keyword(s):  
Stainless Steel ◽  
Proteolytic Activity ◽  
Burkholderia Cepacia ◽  
Raw Milk ◽  
Maximum Activity ◽  
Coagulation Assay ◽  
Milk Coagulation ◽  
C 30 ◽  
Biofilm Development ◽  
Psychrotrophic Strain

The proteolytic activity of a psychrotrophic strain of Burkholderia cepacia isolated from refrigerated raw milk was characterized. Bur. cepacia produced proteolytic activity during growth at refrigeration temperature, with maximum activity at pH 6–7. The enzyme showed relative thermal stability in the range 40–50°C during 25 min, and maintained 80% its initial activity at 76°C/30 s. Milk coagulation assay showed that the crude protease from Bur. cepacia caused coagulation from day 2 for skimmed milk, whereas coagulation was observed from day 5 for whole milk. The adherence of this strain to stainless steel was evaluated, and the substrata had around 107 CFU/cm2 after 15 to 60 min incubation. Results on biofilm development suggest that this bacterium could adhere and to form biofilms even at refrigeration temperatures. These results indicate that Bur. cepacia may represent a potential hazardous to milk and dairy products.

scholarly journals Innovative Control of Biofilms on Stainless Steel Surfaces Using Electrolyzed Water in the Dairy Industry

Foods ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 103
Author(s):  
Rodrigo Jiménez-Pichardo ◽  
Iriana Hernández-Martínez ◽  
Carlos Regalado-González ◽  
José Santos-Cruz ◽  
Yunny Meas-Vong ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Biofilm Formation ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Dairy Industry ◽  
Raw Milk ◽  
Steel Plates ◽  
Heat Processing ◽  
Rrna Gene ◽  
Electrolyzed Water ◽  
Biofilm Development

Biofilms on food-contact surfaces can lead to recurrent contamination. This work aimed to study the biofilm formation process on stainless steel plates used in the dairy industry: 304 surface finish 2B and electropolished; and the effect of a cleaning and disinfection process using alkaline (AEW) and neutral (NEW) electrolyzed water. Milk fouling during heat processing can lead to type A or B deposits, which were analyzed for composition, surface energy, thickness, and roughness, while the role of raw milk microbiota on biofilm development was investigated. Bacteria, yeasts, and lactic acid bacteria were detected using EUB-338, PF2, and Str-493 probes, respectively, whereas Lis-637 probe detected Listeria sp. The genetic complexity and diversity of biofilms varied according to biofilm maturation day, as evaluated by 16S rRNA gene sequence, denaturing gradient gel electrophoresis, and fluorescence in situ hybridization microscopy. From analysis of the experimental designs, a cleaning stage of 50 mg/L NaOH of AEW at 30 °C for 10 min, followed by disinfection using 50 mg/L total available chlorine of NEW at 20 °C for 5 min is a sustainable alternative process to prevent biofilm formation. Fluorescence microscopy was used to visualize the effectiveness of this process.

scholarly journals Electroactivity of Phototrophic River Biofilms and Constitutive Cultivable Bacteria

2011 ◽  
Vol 77 (15) ◽  
pp. 5394-5401 ◽  
Author(s):  
Emilie Lyautey ◽  
Amandine Cournet ◽  
Soizic Morin ◽  
Stéphanie Boulêtreau ◽  
Luc Etcheverry ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Cyclic Voltammetry ◽  
Oxygen Reduction ◽  
Saturated Calomel Electrode ◽  
Bacterial Strains ◽  
Phenotypic Properties ◽  
Content Type ◽  
Population Scale ◽  
River Biofilm ◽  
Biofilm Development

ABSTRACTElectroactivity is a property of microorganisms assembled in biofilms that has been highlighted in a variety of environments. This characteristic was assessed for phototrophic river biofilms at the community scale and at the bacterial population scale. At the community scale, electroactivity was evaluated on stainless steel and copper alloy coupons used both as biofilm colonization supports and as working electrodes. At the population scale, the ability of environmental bacterial strains to catalyze oxygen reduction was assessed by cyclic voltammetry. Our data demonstrate that phototrophic river biofilm development on the electrodes, measured by dry mass and chlorophyllacontent, resulted in significant increases of the recorded potentials, with potentials of up to +120 mV/saturated calomel electrode (SCE) on stainless steel electrodes and +60 mV/SCE on copper electrodes. Thirty-two bacterial strains isolated from natural phototrophic river biofilms were tested by cyclic voltammetry. Twenty-five were able to catalyze oxygen reduction, with shifts of potential ranging from 0.06 to 0.23 V, cathodic peak potentials ranging from −0.36 to −0.76 V/SCE, and peak amplitudes ranging from −9.5 to −19.4 μA. These isolates were diversified phylogenetically (Actinobacteria,Firmicutes,Bacteroidetes, andAlpha-,Beta-, andGammaproteobacteria) and exhibited various phenotypic properties (Gram stain, oxidase, and catalase characteristics). These data suggest that phototrophic river biofilm communities and/or most of their constitutive bacterial populations present the ability to promote electronic exchange with a metallic electrode, supporting the following possibilities: (i) development of electrochemistry-based sensors allowingin situphototrophic river biofilm detection and (ii) production of microbial fuel cell inocula under oligotrophic conditions.

Antibacterial Activity of Reactive Quaternary Ammonium Compounds in Solution and in Nonleachable Coatings

2011 ◽  
Vol 74 (12) ◽  
pp. 2107-2112 ◽  
Author(s):  
G. GOZZELINO ◽  
D. E. ROMERO TOBAR ◽  
N. CHAITIEMWONG ◽  
W. HAZELEGER ◽  
R. BEUMER
Keyword(s):  
Stainless Steel ◽  
Quaternary Ammonium ◽  
Acrylic Resin ◽  
Maximum Activity ◽  
E Coli ◽  
Alkyl Chains ◽  
Acrylic Resins ◽  
Antibacterial Polymers ◽  
Order Of Magnitude ◽  
Free Films

Antibacterial polymers suitable for coating applications without leaching of the biocidal component have been obtained by UV copolymerization of acrylic resins with acrylic monomers containing quaternary ammonium moieties. Suitable reactive biocides, based on quaternary ammonium monomers (QAMs), endowed with undecylacryloyl group and alkyl chains with 2 (QAM-C2), 8 (QAM-C8), and 16 (QAM-C16) carbon atoms have been synthesized. Aqueous solutions of QAMs showed biocidal activity against Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes strains both in suspension and adhered to stainless steel surfaces. QAM-C16 and QAM-C8 evidenced higher activity toward bacteria in suspension and on stainless steel, respectively. The QAMs have shown sufficient reactivity to be copolymerized, by UV irradiation, with a commercial urethane acrylic resin for coating. Bioactivity tests, performed on free films of crosslinked coatings containing 1% of copolymerized QAM, have shown an increasing inactivation effect in the order of magnitude L. monocytogenes < E. coli < S. aureus with a maximum activity of the QAM-C8.

Extracellular Heat-Resistant Proteases of Psychrotrophic Pseudomonads

1983 ◽  
Vol 46 (2) ◽  
pp. 90-94 ◽  
Author(s):  
THAKOR R. PATEL ◽  
FRANCIS M. BARTLETT ◽  
JAWED HAMID
Keyword(s):  
Protease Activity ◽  
Milk Powder ◽  
Milk Proteins ◽  
Raw Milk ◽  
Enzyme Synthesis ◽  
Maximum Activity ◽  
Protease Production ◽  
Divalent Metal Ions ◽  
Extracellular Proteases ◽  
Heat Resistant

Several bacterial isolates from raw milk produced proteases. Most of such 28 isolates were gram-negative rods which were oxidase- and catalase-positive. All the isolates grew at temperatures in the range of 0–35°C, but failed to grow at 37°C. Nineteen of these isolates were tentatively assigned to genus Pseudomonas, and were used in the present investigation. Extracellular proteases from these psychrotrophic pseudomonads were heat-resistant, being able to retain partial activity even after heat-treatment at 120°C for 10 min. Milk proteins were preferred substrates by these proteases although some also hydrolysed bovine serum albumin, hemoglobin and ovalbumin. The optimum pH for the maximum activity was between pH 7.2 and 7.4. Divalent metal ions like Cu2+, Co2+, Hg2+, and Zn2+ were inhibitory to protease activity while Ca2+, Mg2+, and Mn2+ had little or no inhibitory effect on the proteases. Induced levels of protease production were observed when cultures were grown in minimal media containing either casein or nonfat dried milk powder. Glucose, citrate and lactose repressed enzyme synthesis in a minmal salts medium containing either casein or nonfat dried milk powder. Protease activity was also detected in cultures grown in minimal medium containing glutamine. Proteases from different isolates varied in their molecular weights.

Inhibition of Initial Attachment of Injured Salmonella Typhimurium onto Abiotic Surfaces

2017 ◽  
Vol 81 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Woo-Ju Kim ◽  
Ki-Ok Jeong ◽  
Dong-Hyun Kang
Keyword(s):  
Hydrogen Peroxide ◽  
Stainless Steel ◽  
Lactic Acid ◽  
Salmonella Typhimurium ◽  
Food Processing ◽  
Food Contact ◽  
Abiotic Surfaces ◽  
Food Contact Surfaces ◽  
Contact Surfaces ◽  
Biofilm Development

ABSTRACT Following sanitation interventions in food processing facilities, sublethally injured bacterial cells can remain on food contact surfaces. We investigated whether injured Salmonella Typhimurium cells can attach onto abiotic surfaces, which is the initial stage for further biofilm development. We utilized heat, UV, hydrogen peroxide, and lactic acid treatments, which are widely utilized by the food industry. Our results showed that heat, UV, and hydrogen peroxide did not effectively change populations of attached Salmonella Typhimurium. Cells treated with hydrogen peroxide had a slightly higher tendency to adhere to abiotic surfaces, although there was no significant difference between the populations of control and hydrogen peroxide–treated cells. However, lactic acid effectively reduced the number of Salmonella Typhimurium cells attached to stainless steel. We also compared physicochemical changes of Salmonella Typhimurium after application of lactic acid and used hydrogen peroxide as a positive control because only lactic acid showed a decreased tendency for attachment and hydrogen peroxide induced slightly higher numbers of attached bacteria cells. Extracellular polymeric substance produced by Salmonella Typhimurium was not detected in any treatment. Significant differences in hydrophobicity were not observed. Surface charges of cell membranes did not show relevant correlation with numbers of attached cells, whereas autoaggregation showed a positive correlation with attachment to stainless steel. Our results highlight that when lactic acid is applied in a food processing facility, it can effectively interfere with adhesion of injured Salmonella Typhimurium cells onto food contact surfaces.

scholarly journals Rheology and Microstructures of Rennet Gels from Differently Heated Goat Milk

Foods ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 283
Author(s):  
Zorana Miloradovic ◽  
Nemanja Kljajevic ◽  
Jelena Miocinovic ◽  
Steva Levic ◽  
Vladimir B. Pavlovic ◽  
...  
Keyword(s):  
Heating Temperature ◽  
Goat Milk ◽  
High Heat ◽  
Yield Efficiency ◽  
Rennet Coagulation ◽  
Heat Treated ◽  
Cross Links ◽  
Milk Coagulation ◽  
C 30 ◽  
The Moment

Rennet coagulation of goat milk heated to 65 °C/30 min (Gc), 80 °C/5 min (G8) and 90 °C/5 min (G9) was studied. A rheometer equipped with a vane geometry tool was used to measure milk coagulation parameters and viscoelastic properties of rennet gels. Yield parameters: curd yield, laboratory curd yield and curd yield efficiency were measured and calculated. Scanning electron microscopy of rennet gels was conducted. Storage moduli (G’) of gels at the moment of cutting were 19.9 ± 1.71 Pa (Gc), 11.9 ± 1.96 Pa (G8) and 7.3 ± 1.46 Pa (G9). Aggregation rate and curd firmness decreased with the increase of milk heating temperature, while coagulation time did not change significantly. High heat treatment of goat milk had a significant effect on both laboratory curd yield and curd yield. However, laboratory curd yield (27.7 ± 1.84%) of the G9 treatment was unreasonably high compared to curd yield (15.4 ± 0.60%). The microstructure of G9 was notably different compared to Gc and G8, with a denser and more compact microstructure, smaller paracasein micelles and void spaces in a form of cracks indicating weaker cross links. The findings of this study might serve as the bases for the development of different cheese types produced from high-heat-treated goat milk.

scholarly journals Pronounced Effect of the Nature of the Inoculum on Biofilm Development in Flow Systems

2010 ◽  
Vol 76 (18) ◽  
pp. 6025-6031 ◽  
Author(s):  
Otini Kroukamp ◽  
Romeo G. Dumitrache ◽  
Gideon M. Wolfaardt
Keyword(s):  
Growth Rate ◽  
Steady State ◽  
Removal Rate ◽  
Maximum Activity ◽  
Nutrient Concentrations ◽  
Lag Phase ◽  
Dominant Form ◽  
Biofilm Growth ◽  
Flow Systems ◽  
Biofilm Development

ABSTRACT Biofilm formation renders sessile microbial populations growing in continuous-flow systems less susceptible to variation in dilution rate than planktonic cells, where dilution rates exceeding an organism's maximum growth rate (μmax) results in planktonic cell washout. In biofilm-dominated systems, the biofilm's overall μmax may therefore be more relevant than the organism's μmax, where the biofilm μmax is considered as a net process dependent on the adsorption rate, growth rate, and removal rate of cells within the biofilm. Together with lag (acclimation) time, the biofilm's overall μmax is important wherever biofilm growth is a dominant form, from clinical settings, where the aim is to prevent transition from lag to exponential growth, to industrial bioreactors, where the aim is to shorten the lag and rapidly reach maximum activity. The purpose of this study was to measure CO2 production as an indicator of biofilm activity to determine the effect of nutrient type and concentration and of the origin of the inoculum on the length of the lag phase, biofilm μmax, and steady-state metabolic activity of Pseudomonas aeruginosa PA01 (containing gfp), Pseudomonas fluorescens CT07 (containing gfp), and a mixed community. As expected, for different microorganisms the lengths of the lag phase in biofilm development and the biofilm μmax values differ, whereas different nutrient concentrations result in differences in the lengths of lag phase and steady-state values but not in biofilm μmax rates. The data further showed that inocula from different phenotypic origins give rise to lag time of different lengths and that this influence persists for a number of generations after inoculation.

scholarly journals Action of cardosin A from Cynara humilis on ovine and caprine caseinates

2000 ◽  
Vol 67 (3) ◽  
pp. 449-454 ◽  
Author(s):  
SOFIA V. SILVA ◽  
F. XAVIER MALCATA
Keyword(s):  
Proteolytic Activity ◽  
Small Ruminants ◽  
Sodium Caseinate ◽  
Cheese Ripening ◽  
Caprine Milk ◽  
Proteolytic Action ◽  
Milk Coagulation ◽  
Cardosin A ◽  
Intermediate System

In the Iberian Peninsula, the proteinases present in the flowers of members of the Cynara genus, C. cardunculus, C. humilis and C. scolymus, have for many years been successfully used in the manufacture of traditional cheeses from ovine and/or caprine milk on individual farms (Vieira de Sá & Barbosa, 1972; Trujillo et al. 1994). In Portugal, C. cardunculus is the species most frequently employed. Although commercial thistle was tentatively assumed to be pure in taxonomic terms, accurate analyses have shown that the flowers of C. cardunculus are often mixed with flowers of C. humilis (Pires et al. 1994). The clotting activity of C. humilis is due to an aspartic proteinase, currently designated cardosin A and similar to another enzyme obtained from C. cardunculus. This enzyme is similar in specificity and activity to chymosin (Pires et al. 1994).The action of cardosin A from C. cardunculus upon ovine and caprine caseins has been reported recently (Ramalho-Santos et al. 1996; Simo4es, 1998; Sousa & Malcata, 1998), but as yet there is no information on the proteolytic activity of the proteinase from C. humilis upon caseins from milks other than bovine. Caseins from small ruminants' milks are the usual substrates of cardosin during milk coagulation and cheese ripening, and sodium caseinate represents an intermediate system between isolated caseins and the cheese matrix that is free from interference by fat. Thus ovine and caprine caseinates may be useful substrates for investigating the proteolytic activity of cardosin.The aim of the present study was to compare the action of pure cardosin A, obtained from C. humilis, on caprine and ovine caseinates, and to assess the in vitro contribution of this enzyme to the overall proteolytic action of thistle rennet.

scholarly journals Use of Synthetic Hybrid Strains To Determine the Role of Replicon 3 in Virulence of the Burkholderia cepacia Complex

2017 ◽  
Vol 83 (13) ◽  
Author(s):  
Kirsty Agnoli ◽  
Roman Freitag ◽  
Margarida C. Gomes ◽  
Christian Jenul ◽  
Angela Suppiger ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Proteolytic Activity ◽  
Burkholderia Cepacia ◽  
Burkholderia Cenocepacia ◽  
Burkholderia Cepacia Complex ◽  
Antifungal Compounds ◽  
Biotechnological Potential ◽  
Content Type ◽  
The Third

ABSTRACT The Burkholderia cepacia complex (Bcc) displays a wealth of metabolic diversity with great biotechnological potential, but the utilization of these bacteria is limited by their opportunistic pathogenicity to humans. The third replicon of the Bcc, megaplasmid pC3 (0.5 to 1.4 Mb, previously chromosome 3), is important for various phenotypes, including virulence, antifungal, and proteolytic activities and the utilization of certain substrates. Approximately half of plasmid pC3 is well conserved throughout sequenced Bcc members, while the other half is not. To better locate the regions responsible for the key phenotypes, pC3 mutant derivatives of Burkholderia cenocepacia H111 carrying large deletions (up to 0.58 Mb) were constructed with the aid of the FLP-FRT (FRT, flippase recognition target) recombination system from Saccharomyces cerevisiae. The conserved region was shown to confer near-full virulence in both Caenorhabditis elegans and Galleria mellonella infection models. Antifungal activity was unexpectedly independent of the part of pC3 bearing a previously identified antifungal gene cluster, while proteolytic activity was dependent on the nonconserved part of pC3, which encodes the ZmpA protease. To investigate to what degree pC3-encoded functions are dependent on chromosomally encoded functions, we transferred pC3 from Burkholderia cenocepacia K56-2 and Burkholderia lata 383 into other pC3-cured Bcc members. We found that although pC3 is highly important for virulence, it was the genetic background of the recipient that determined the pathogenicity level of the hybrid strain. Furthermore, we found that important phenotypes, such as antifungal activity, proteolytic activity, and some substrate utilization capabilities, can be transferred between Bcc members using pC3. IMPORTANCE The Burkholderia cepacia complex (Bcc) is a group of closely related bacteria with great biotechnological potential. Some strains produce potent antifungal compounds and can promote plant growth or degrade environmental pollutants. However, their agricultural potential is limited by their opportunistic pathogenicity, particularly for cystic fibrosis patients. Despite much study, their virulence remains poorly understood. The third replicon, pC3, which is present in all Bcc isolates and is important for pathogenicity, stress resistance, and the production of antifungal compounds, has recently been reclassified from a chromosome to a megaplasmid. In this study, we identified regions on pC3 important for virulence and antifungal activity and investigated the role of the chromosomal background for the function of pC3 by exchanging the megaplasmid between different Bcc members. Our results may open a new avenue for the construction of antifungal but nonpathogenic Burkholderia hybrids. Such strains may have great potential as biocontrol strains for protecting fungus-borne diseases of plant crops.

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