scholarly journals Impact of low-concentrated acidic electrolysed water obtained by membrane electrolysis on the decontamination of meat microbiota

2015 ◽  
Vol 59 (3) ◽  
pp. 369-376 ◽  
Author(s):  
Ewa Brychcy ◽  
Andrzej Jarmoluk ◽  
Krzysztof Marycz
Keyword(s):  
Micrococcus Luteus ◽  
Bactericidal Effect ◽  
Plate Count ◽  
E Coli ◽  
Log Reduction ◽  
Bacterial Cultures ◽  
Number Of Microorganisms ◽  
Plate Count Method ◽  
Bacterial Cell Morphology ◽  
Pure Bacterial Cultures

AbstractThe influence of acidic electrolysed water (AEW) treatment on inactivation of pure bacterial cultures inoculated onto the surface of agarised media and surface microbiota of pork meat were examined. Low-concentrated AEW (low concentration of sodium chloride and low current electrolysis) was generated by electrolysis (5 or 10 min) of 0.001% or 0.01% NaCl solution. The number of viable microorganisms was determined using a plate count method. The effect of AEW on bacterial cell morphology were investigated using scanning electron microscopy (SEM). After treatment with AEW, a significant, about 3.00 log reduction ofPseudomonas fluorescens, Yersinia enterocolitica, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Listeria monocytogenes,andMicrococcus luteuspopulations was observed. In the AEW treatment of pork, the highest reduction of total number of microorganisms (2.1 log reduction), yeast and moulds (2.5-2.6 log reduction), and psychrotrophs (more than 1 log reduction) was observed after spraying with 0.001% NaCl subjected to 10 min electrolysis. SEM revealed disruption and lysis ofE. coliandS. aureuscells treated with AEW, suggesting a bactericidal effect. Higher available chlorine concentration (0.37-8.45 mg/L), redox potential (863.1-1049.8 mV), and lower pH (2.73-3.70) had an influence on the shape of bacteria and the number of breaks in the bacterial membrane.

scholarly journals Fluorescence Assay for Evaluating Microbicidal Activity of Hand Antiseptics

2015 ◽  
Vol 81 (21) ◽  
pp. 7443-7447
Author(s):  
Rosa M. Lopez-Gigosos ◽  
Alberto Mariscal ◽  
Eloisa Mariscal-Lopez ◽  
Mario Gutierrez-Bedmar ◽  
Joaquin Fernandez
Keyword(s):  
Plate Count ◽  
Content Type ◽  
E Coli ◽  
Glucuronidase Activity ◽  
Count Method ◽  
Fluorescence Methods ◽  
Fluorescence Level ◽  
Assay Time ◽  
Plate Count Method ◽  
Time Required

ABSTRACTWe developed a fluorescent β-d-glucuronidase activity (BGA)-based assay for detecting and quantifyingEscherichia coliin samples to assess the biocide efficacy of hand antiseptics. The fluorescence level is proportional to the number of viableE. coliorganisms present. We compared our assay results to those of theE. coliplate count method specified by the European standard for testing hygienic hand rub disinfectant products (EN1500). The plate count method requires excessive handling and materials and is not valid if the number of organisms per plate is too low or high for counting in many of the samples. We optimized the fluorescent assay based on the cleavage of 4-methylumbelliferyl-β-d-glucuronide by adding 4-nitrophenyl-β-d-glucuronide, a nonfluorogenic BGA substrate, to induce glucuronidase activity and reduce assay time. Furthermore, our method can be automated and eliminates the need for multiple dilutions. Fluorescence was temporally monitored, and the time required to reach a specific value of fluorescence was correlated with the initial number of viableE. coliorganisms on the samples. There was a positive correlation (P< 0.05) with a high correlation coefficient (R2= 0.82) between theE. colicounts by plate count and fluorescence methods. Reported effects in fluorescent BGA were compared to the EN1500 plate count method with five hand disinfectants. We found our method more advantageous, because it was as sensitive as the EN1500 method, requires less time to complete, and is less expensive and less laborious than conventional plating techniques.

scholarly journals Antibacterial Activity of Biosecur® Citrus Extract Surface Cleaner Against Vibrio Vulnificus

2013 ◽  
Vol 7 (1) ◽  
pp. 130-134 ◽  
Author(s):  
Jiemin Cormier ◽  
Ronson Scott ◽  
Marlene Janes
Keyword(s):  
Antibacterial Activity ◽  
Vibrio Vulnificus ◽  
Organic Food ◽  
Residual Activity ◽  
Residual Effect ◽  
Plate Count ◽  
Time Intervals ◽  
Log Reduction ◽  
Plate Count Method ◽  
Citrus Extract

This study evaluated the antibacterial activity of Biosecur®citrus extract surface cleaner againstVibrio vulnificususing plate count method. Two concentrations, 0.5% and 2% of Biosecur®surface cleaner were plated onVibrio vulnificusAgar (VVA) and tested for reduction ofVibrio vulnificus. In order to investigate the lasting residual activity of Biosecur®, antibacterial activity tests were also performed at time intervals up to 2.5 h after Biosecur®was plated on VVA. Biosecur®showed 6-log reduction ofVibrio vulnificusat 2%, and 3-log reduction ofVibrio vulnificusat 0.5%. The antibacterial activity of 2% Biosecur®againstVibrio vulnificuswas shown to be equivalent to that of tetracycline. The residual activity of 2% Biosecur®was shown to maintain for at least 2.5 h after application. This study confirmed the high activity and long lasting residual effect of a safe, non-toxic organic food grade surface cleaner.

Bactericidal Activity of Isothiocyanate against Pathogens on Fresh Produce†

2000 ◽  
Vol 63 (1) ◽  
pp. 25-30 ◽  
Author(s):  
CHIA-MIN LIN ◽  
JEONGMOK KIM ◽  
WEN-XIAN DU ◽  
CHENG-I WEI
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Bactericidal Activity ◽  
Bactericidal Effect ◽  
Escherichia Coli O157 ◽  
Methyl Isothiocyanate ◽  
E Coli ◽  
Log Reduction ◽  
Iceberg Lettuce ◽  
Resistant Strains

The bactericidal activity of allyl and methyl isothiocyanate (AITC and MITC) was tested with a rifampicin-resistant strain of Salmonella Montevideo and streptomycin-resistant strains of Escherichia coli O157:H7 and Listeria monocytogenes Scott A. Iceberg lettuce inoculated with high (107 to 108 CFU/g) and low (103 to 104 CFU/g) concentrations of bacterial pathogens was treated with AITC and MITC in sealed containers at 4°C for 4 days. AITC showed stronger bactericidal activity than MITC against E. coli O157:H7 and Salmonella Montevideo, whereas MITC showed stronger activity against L. monocytogenes than E. coli O157:H7 and Salmonella Montevideo. Up to 8-log reduction occurred with E. coli O157:H7 and Salmonella Montevideo on lettuce following treatment with vapor generated from 400 μl of AITC for 2 and 4 days, respectively. AITC was used to treat tomatoes inoculated with Salmonella Montevideo on stem scars and skin and apples inoculated with E. coli O157:H7 on stem scars. The bactericidal effect of AITC varied with bacteria species and exposure time. Salmonella Montevideo inoculated on tomato skin was more sensitive to AITC than that on stem scars. Treatment with vapor generated from 500 μl of AITC caused an 8-log reduction in bacteria on tomato skin but only a 5-log reduction on tomato stem scars. The bactericidal activity of AITC was weaker for E. coli O157:H7 on apple stem scars; only a 3-log reduction in bacteria occurred when 600 μl of AITC was used.

scholarly journals Antibacterial Activity and Mechanism of Action of the Silver Ion in Staphylococcus aureus and Escherichia coli

2008 ◽  
Vol 74 (7) ◽  
pp. 2171-2178 ◽  
Author(s):  
Woo Kyung Jung ◽  
Hye Cheong Koo ◽  
Ki Woo Kim ◽  
Sook Shin ◽  
So Hyun Kim ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Mechanism Of Action ◽  
Antibacterial Effect ◽  
Silver Ion ◽  
Plate Count ◽  
E Coli ◽  
Count Method ◽  
Plate Count Method ◽  
Conventional Plate

ABSTRACT The antibacterial effect and mechanism of action of a silver ion solution that was electrically generated were investigated for Staphylococcus aureus and Escherichia coli by analyzing the growth, morphology, and ultrastructure of the bacterial cells following treatment with the silver ion solution. Bacteria were exposed to the silver ion solution for various lengths of time, and the antibacterial effect of the solution was tested using the conventional plate count method and flow cytometric (FC) analysis. Reductions of more than 5 log10 CFU/ml of both S. aureus and E. coli bacteria were confirmed after 90 min of treatment with the silver ion solution. Significant reduction of S. aureus and E. coli cells was also observed by FC analysis; however, the reduction rate determined by FC analysis was less than that determined by the conventional plate count method. These differences may be attributed to the presence of bacteria in an active but nonculturable (ABNC) state after treatment with the silver ion solution. Transmission electron microscopy showed considerable changes in the bacterial cell membranes upon silver ion treatment, which might be the cause or consequence of cell death. In conclusion, the results of the present study suggest that silver ions may cause S. aureus and E. coli bacteria to reach an ABNC state and eventually die.

Internalization of Bacterial Pathogens in Tomatoes and Their Control by Selected Chemicals

2004 ◽  
Vol 67 (7) ◽  
pp. 1353-1358 ◽  
Author(s):  
L. S. IBARRA-SÁNCHEZ ◽  
S. ALVARADO-CASILLAS ◽  
M. O. RODRÍGUEZ-GARCÍA ◽  
N. E. MARTÍNEZ-GONZÁLES ◽  
A. CASTILLO
Keyword(s):  
Lactic Acid ◽  
Salmonella Typhimurium ◽  
Tap Water ◽  
Plate Count ◽  
Bacterial Suspension ◽  
Enrichment Method ◽  
E Coli ◽  
Internal Ph ◽  
Plate Count Method ◽  
The Mean

The effect of different washing or sanitizing agents was compared for preventing or reducing surface and internal contamination of tomatoes by Salmonella Typhimurium and Escherichia coli O157:H7. The tomatoes were inoculated by dipping them in a bacterial suspension containing approximately 6.0 log CFU/ml of each pathogen and then rinsing them with tap water, hypochlorite solution (250 mg/liter), or lactic acid solution (2%, wt/vol). All treatments were applied by dipping or spraying, and solutions were applied at 5, 25, 35, and 55°C. With the exception of the lactic acid dip at 5°C, all treatments reduced both pathogens on the surfaces of the tomatoes by at least 2.9 cycles. No significantly different results were obtained (P &gt; 0.05) with the dipping and spraying techniques. For internalized pathogens, the mean counts for tomatoes treated with water alone or with chlorine ranged from 0.8 to 2.1 log CFU/g. In contrast, after lactic acid spray treatment, all core samples of tomatoes tested negative for Salmonella Typhimurium and, except for one sample with a low but detectable count, all samples tested negative for E. coli O157:H7 with a plate count method. When the absence of pathogens was verified by an enrichment method, Salmonella was not recovered from any samples, whereas two of four samples tested positive for E. coli O157:H7 even though the counts were negative. Few cells of internalized pathogens were able to survive in the center of the tomato during storage at room temperature (25 to 28°C). The average superficial pH of tomatoes treated with tap water, chlorine, or lactic acid was 4.9 to 5.2, 4.1 to 4.3, and 2.5, respectively (P &lt; 0.05), whereas no differences were observed in the internal pH (3.6 to 3.7) of the tomatoes treated with different sanitizers. The general practice in the tomato industry is to wash the tomatoes in chlorinated water. However, chlorine is rapidly degraded by organic matter usually present in produce. Therefore, lactic acid sprays may be a more effective alternative for decontaminating tomato surfaces. The use of warm (55°C) sprays could reduce pathogen internalization during washing.

scholarly journals Rapid Pasteurization of Apple Juice Using a New Ultrasonic Reactor

Foods ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 801
Author(s):  
Zahra Moaddabdoost Baboli ◽  
Leonard Williams ◽  
Guibing Chen
Keyword(s):  
Antioxidant Activity ◽  
Apple Juice ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Ultrasound Treatment ◽  
Plate Count ◽  
Total Phenolic ◽  
E Coli ◽  
Log Reduction ◽  
Dpph Radical Scavenging

A new ultrasonic reactor was used to rapidly inactivate Escherichia coli and Staphylococcus aureus in apple juice. It was found that high pulp content made ultrasound less lethal to S. aureus, while it had no significant effect on E. coli. When the pulp free apple juice was ultrasonically processed, the 5-log reduction time was 35 s for E. coli at 60 °C and 30 s for S. aureus at 62 °C. Ultrasound treatment had no significant effect on antioxidant activity determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, but it significantly increased the total phenolic content. The treatment also resulted in more stable juice with higher uniformity. During 28 d of storage at 4 °C, the total plate count in apple juice ultrasonically treated at 60 °C for 35 s remained around 1.00 log CFU/mL, whereas it was nearly zero for a stronger ultrasound treatment at 62 °C for 30 s. These values were much lower than those in the untreated one, which increased from 3.65 log CFU/mL to 8.36 log CFU/mL during the storage. At the end of the storage, the control and thermally treated apple juice lost almost 70% of antioxidant activity, whereas the ultrasonically treated juice only lost 20–40%.

STUDIES ON THE MICROBIOLOGY OF RECONTAMINATED STERILIZED SOIL IN RELATION TO ITS INFESTATION WITH OPHIOBOLUS GRAMINIS SACC.

1943 ◽  
Vol 21c (11) ◽  
pp. 343-350 ◽  
Author(s):  
R. A. Ludwig ◽  
A. W. Henry
Keyword(s):  
Trichoderma Viride ◽  
Severe Infection ◽  
Black Soil ◽  
Plate Count ◽  
Wheat Seedlings ◽  
Number Of Microorganisms ◽  
Plate Count Method ◽  
Unsterilized Soil ◽  
Suppressive Action ◽  
Take All

In these studies recontaminated steam-sterilized black soil, when infested with the take-all fungus, Ophiobolus graminis, gave, as a rule, less severe infection of wheat seedlings than similarly infested unsterilized soil. One explanation suggested is that the microflora that develops in sterilized soil following recontamination has a greater suppressive action on Ophiobolus graminis than that normally present in unsterilized soil. These two microfloras were found to differ both quantitatively and qualitatively. In general the number of microorganisms, as determined by the plate count method, was found to be much greater in sterilized recontaminated soil than in unsterilized soil. The fact that the fungus Trichoderma viride develops rapidly and becomes a dominant organism in sterilized recontaminated soil is considered to be of especial significance. The antagonism of this fungus toward Ophiobolus graminis probably plays an important role in suppressing the latter.

scholarly journals The Effect of Disinfectants on Quinolone Resistant E. coli (QREC) in Biofilm

2020 ◽  
Vol 8 (11) ◽  
pp. 1831
Author(s):  
Ane Mohr Osland ◽  
Lene K. Vestby ◽  
Live L. Nesse
Keyword(s):  
Escherichia Coli ◽  
Stainless Steel ◽  
Bactericidal Effect ◽  
E Coli ◽  
Planktonic Bacteria ◽  
Colony Forming Units ◽  
Number Of Microorganisms ◽  
Reduction Effect ◽  
Susceptibility Tests ◽  
Biofilm Matrix

The aim of disinfection is to reduce the number of microorganisms on surfaces which is a challenge due to biofilms. In the present study, six quinolone resistant Escherichia coli (QREC) strains with three different biofilm matrix compositions were included to assess the log10 colony forming units (CFU) reduction effect of three disinfectants at various exposure times on biofilm of different ages and morphotypes. Biofilm was formed on stainless steel coupons for two and five days before transferred to tubes with Virocid 0, 25%, VirkonS 1%, and TP990 1% and left for various exposure times. The biofilms were scraped off and serial dilutions were spread on blood agar plates where colony forming units (CFU) were counted. A mean log10 CFU reduction ≥4 was seen on two-day-old biofilm with VirkonS and Virocid (30 min) but not on five-day old biofilm. TP990 did not display sufficient effect under the conditions tested. The bactericidal effect was inferior to that reported on planktonic bacteria. The findings of this study should be considered when establishing both disinfectant routines and standard susceptibility tests, which further should accommodate E. coli biofilms and not only Pseudomonas as is the case today.

Addition of Fumaric Acid and Sodium Benzoate as an Alternative Method To Achieve a 5-log Reduction of Escherichia coli O157:H7 Populations in Apple Cider

2002 ◽  
Vol 65 (3) ◽  
pp. 476-483 ◽  
Author(s):  
JUSTIN E. COMES ◽  
ROBERT B. BEELMAN
Keyword(s):  
Escherichia Coli ◽  
Fumaric Acid ◽  
Sodium Benzoate ◽  
Bactericidal Effect ◽  
Escherichia Coli O157 ◽  
Refrigerated Storage ◽  
Apple Cider ◽  
E Coli ◽  
Log Reduction ◽  
Strong Linear Correlation

A study was conducted to develop a preservative treatment capable of the Food and Drug Administration–mandated 5-log reduction of Escherichia coli O157:H7 populations in apple cider. Unpreserved apple cider was treated with generally recognized as safe acidulants and preservatives before inoculation with E. coli O157:H7 in test tubes and subjected to mild heat treatments (25, 35, and 45°C) followed by refrigerated storage (4°C). Fumaric acid had significant (P &lt; 0.05) bactericidal effect when added to cider at 0.10% (wt/vol) and adjusted to pH 3.3, but citric and malic acid had no effect. Strong linear correlation (R2 = 0.96) between increasing undissociated fumaric acid concentrations and increasing log reductions of E. coli O157:H7 in apple cider indicated the undissociated acid to be the bactericidal form. The treatment that achieved the 5-log reduction in three commercial ciders was the addition of fumaric acid (0.15%, wt/vol) and sodium benzoate (0.05%, wt/vol) followed by holding at 25°C for 6 h before 24 h of refrigeration at 4°C. Subsequent experiments revealed that the same preservatives added to cider in flasks resulted in a more than 5-log reduction in less than 5 and 2 h when held at 25 and 35°C, respectively. The treatment also significantly (P &lt; 0.05) reduced total aerobic counts in commercial ciders to populations less than those of pasteurized and raw ciders from the same source (after 5 and 21 days of refrigerated storage at 4°C, respectively). Sensory evaluation of the same ciders revealed that consumers found the preservative-treated cider to be acceptable.

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