scholarly journals Kinetics of Inactivation of Bacillus subtilis subsp.nigerSpores and Staphylococcus albus on Paper by Chlorine Dioxide Gas in an Enclosed Space

2016 ◽  
Vol 82 (10) ◽  
pp. 3061-3069 ◽  
Author(s):  
Tao Wang ◽  
Jinhui Wu ◽  
Jiancheng Qi ◽  
Limei Hao ◽  
Ying Yi ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Chlorine Dioxide ◽  
Biological Indicators ◽  
Inactivation Kinetics ◽  
Rapid Improvement ◽  
Content Type ◽  
Gas Concentration ◽  
First Order ◽  
Log Reduction ◽  
Kinetics Of

ABSTRACTBacillus subtilissubsp.nigerspore andStaphylococcus albusare typical biological indicators for the inactivation of airborne pathogens. The present study characterized and compared the behaviors ofB. subtilissubsp.nigerspores andS. albusin regard to inactivation by chlorine dioxide (ClO2) gas under different gas concentrations and relative humidity (RH) conditions. The inactivation kinetics under different ClO2gas concentrations (1 to 5 mg/liter) were determined by first-order and Weibull models. A new model (the Weibull-H model) was established to reveal the inactivation tendency and kinetics for ClO2gas under different RH conditions (30 to 90%). The results showed that both the gas concentration and RH were significantly (P< 0.05) and positively correlated with the inactivation of the two chosen indicators. There was a rapid improvement in the inactivation efficiency under high RH (>70%). Compared with the first-order model, the Weibull and Weibull-H models demonstrated a better fit for the experimental data, indicating nonlinear inactivation behaviors of the vegetative bacteria and spores following exposure to ClO2gas. The times to achieve a six-log reduction ofB. subtilissubsp.nigerspore andS. albuswere calculated based on the established models. Clarifying the kinetics of inactivation ofB. subtilissubsp.nigerspores andS. albusby ClO2gas will allow the development of ClO2gas treatments that provide an effective disinfection method.IMPORTANCEChlorine dioxide (ClO2) gas is a novel and effective fumigation agent with strong oxidization ability and a broad biocidal spectrum. The antimicrobial efficacy of ClO2gas has been evaluated in many previous studies. However, there are presently no published models that can be used to describe the kinetics of inactivation of airborne pathogens by ClO2gas under different gas concentrations and RH conditions. The first-order and Weibull (Weibull-H) models established in this study can characterize and compare the behaviors ofBacillus subtilissubsp.nigerspores andStaphylococcusalbusin regard to inactivation by ClO2gas, determine the kinetics of inactivation of two chosen strains under different conditions of gas concentration and RH, and provide the calculated time to achieve a six-log reduction. These results will be useful to determine effective conditions for ClO2gas to inactivate airborne pathogens in contaminated air and other environments and thus prevent outbreaks of airborne illness.

Determination of the Thermal Inactivation Kinetics of Listeria monocytogenes, Salmonella enterica, and Escherichia coli O157:H7 and non-O157 in Buffer and a Spinach Homogenate

2015 ◽  
Vol 78 (8) ◽  
pp. 1467-1471 ◽  
Author(s):  
EMEFA ANGELICA MONU ◽  
MALCOND VALLADARES ◽  
DORIS H. D'SOUZA ◽  
P. MICHAEL DAVIDSON
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Thermal Inactivation ◽  
Inactivation Kinetics ◽  
Mild Heat ◽  
Log Reduction ◽  
D Values ◽  
Heat Processes ◽  
Kinetics Of

Produce has been associated with a rising number of foodborne illness outbreaks. While much produce is consumed raw, some is treated with mild heat, such as blanching or cooking. The objectives of this research were to compare the thermal inactivation kinetics of Listeria monocytogenes, Salmonella enterica, Shiga toxin–producing Escherichia coli (STEC) O157:H7, and non-O157 STEC in phosphate-buffered saline (PBS; pH 7.2) and a spinach homogenate and to provide an estimate of the safety of mild heat processes for spinach. Five individual strains of S. enterica, L. monocytogenes, STEC O157:H7, and non-O157 STEC were tested in PBS in 2-ml glass vials, and cocktails of the organisms were tested in blended spinach in vacuum-sealed bags. For Listeria and Salmonella at 56 to 60°C, D-values in PBS ranged from 4.42 ± 0.94 to 0.35 ± 0.03 min and 2.11 ± 0.14 to 0.16 ± 0.03 min, respectively. D-values at 54 to 58°C were 5.18 ± 0.21 to 0.53 ± 0.04 min for STEC O157:H7 and 5.01 ± 0.60 to 0.60 ± 0.13 min for non-O157 STEC. In spinach at 56 to 60°C, Listeria D-values were 11.77 ± 2.18 to 1.22 ± 0.12 min and Salmonella D-values were 3.51 ± 0.06 to 0.47 ± 0.06 min. D-values for STEC O157:H7 and non-O157 STEC were 7.21 ± 0.17 to 1.07 ± 0.11 min and 5.57 ± 0.38 to 0.99 ± 0.07 min, respectively, at 56 to 60°C. In spinach, z-values were 4.07 ± 0.16, 4.59 ± 0.26, 4.80 ± 0.92, and 5.22 ± 0.20°C for Listeria, Salmonella, STEC O157:H7, and non-O157 STEC, respectively. Results indicated that a mild thermal treatment of blended spinach at 70°C for less than 1 min would result in a 6-log reduction of all pathogens tested. These findings may assist the food industry in the design of suitable mild thermal processes to ensure food safety.

Thermal Inactivation Kinetics of Sporolactobacillus nakayamae Spores, a Spoilage Bacterium Isolated from a Model Mashed Potato–Scallion Mixture

2016 ◽  
Vol 79 (9) ◽  
pp. 1482-1489
Author(s):  
HAYRIYE BOZKURT ◽  
JAIRUS R. D. DAVID ◽  
RYAN J. TALLEY ◽  
D. SCOTT LINEBACK ◽  
P. MICHAEL DAVIDSON
Keyword(s):  
Heat Resistance ◽  
Thermal Inactivation ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
Order Model ◽  
First Order ◽  
Different Temperatures ◽  
Spoilage Bacterium ◽  
D Values ◽  
Kinetics Of

ABSTRACT Sporolactobacillus species have been occasionally isolated from spoiled foods and environmental sources. Thus, food processors should be aware of their potential presence and characteristics. In this study, the heat resistance and influence of the growth and recovery media on apparent heat resistance of Sporolactobacillus nakayamae spores were studied and described mathematically. For each medium, survivor curves and thermal death curves were generated for different treatment times (0 to 25 min) at different temperatures (70, 75, and 80°C) and Weibull and first-order models were compared. Thermal inactivation data for S. nakayamae spores varied widely depending on the media formulations used, with glucose yeast peptone consistently yielding the highest D-values for the three temperatures tested. For this same medium, the D-values ranged from 25.24 ± 1.57 to 3.45 ± 0.27 min for the first-order model and from 24.18 ± 0.62 to 3.50 ± 0.24 min for the Weibull model at 70 and 80°C, respectively. The z-values determined for S. nakayamae spores were 11.91 ± 0.29°C for the Weibull model and 11.58 ± 0.43°C for the first-order model. The calculated activation energy was 200.5 ± 7.3 kJ/mol for the first-order model and 192.8 ± 22.1 kJ/mol for the Weibull model. The Weibull model consistently produced the best fit for all the survival curves. This study provides novel and precise information on thermal inactivation kinetics of S. nakayamae spores that will enable reliable thermal process calculations for eliminating this spoilage bacterium.

scholarly journals Thermal Inactivation Kinetics of Human Norovirus Surrogates and Hepatitis A Virus in Turkey Deli Meat

2015 ◽  
Vol 81 (14) ◽  
pp. 4850-4859 ◽  
Author(s):  
Hayriye Bozkurt ◽  
Doris H. D'Souza ◽  
P. Michael Davidson
Keyword(s):  
Hepatitis A ◽  
Thermal Inactivation ◽  
Hepatitis A Virus ◽  
Weibull Model ◽  
Activation Energies ◽  
Inactivation Kinetics ◽  
Order Model ◽  
Decimal Reduction Time ◽  
First Order ◽  
Kinetics Of

ABSTRACTHuman noroviruses (HNoV) and hepatitis A virus (HAV) have been implicated in outbreaks linked to the consumption of presliced ready-to-eat deli meats. The objectives of this research were to determine the thermal inactivation kinetics of HNoV surrogates (murine norovirus 1 [MNV-1] and feline calicivirus strain F9 [FCV-F9]) and HAV in turkey deli meat, compare first-order and Weibull models to describe the data, and calculate Arrhenius activation energy values for each model. TheD(decimal reduction time) values in the temperature range of 50 to 72°C calculated from the first-order model were 0.1 ± 0.0 to 9.9 ± 3.9 min for FCV-F9, 0.2 ± 0.0 to 21.0 ± 0.8 min for MNV-1, and 1.0 ± 0.1 to 42.0 ± 5.6 min for HAV. Using the Weibull model, thetD = 1(time to destroy 1 log) values for FCV-F9, MNV-1, and HAV at the same temperatures ranged from 0.1 ± 0.0 to 11.9 ± 5.1 min, from 0.3 ± 0.1 to 17.8 ± 1.8 min, and from 0.6 ± 0.3 to 25.9 ± 3.7 min, respectively. Thez(thermal resistance) values for FCV-F9, MNV-1, and HAV were 11.3 ± 2.1°C, 11.0 ± 1.6°C, and 13.4 ± 2.6°C, respectively, using the Weibull model. Thezvalues using the first-order model were 11.9 ± 1.0°C, 10.9 ± 1.3°C, and 12.8 ± 1.7°C for FCV-F9, MNV-1, and HAV, respectively. For the Weibull model, estimated activation energies for FCV-F9, MNV-1, and HAV were 214 ± 28, 242 ± 36, and 154 ± 19 kJ/mole, respectively, while the calculated activation energies for the first-order model were 181 ± 16, 196 ± 5, and 167 ± 9 kJ/mole, respectively. Precise information on the thermal inactivation of HNoV surrogates and HAV in turkey deli meat was generated. This provided calculations of parameters for more-reliable thermal processes to inactivate viruses in contaminated presliced ready-to-eat deli meats and thus to reduce the risk of foodborne illness outbreaks.

scholarly journals Improvement of Biological Indicators by Uniformly Distributing Bacillus subtilis Spores in Monolayers To Evaluate Enhanced Spore Decontamination Technologies

2016 ◽  
Vol 82 (7) ◽  
pp. 2031-2038 ◽  
Author(s):  
Marina Raguse ◽  
Marcel Fiebrandt ◽  
Katharina Stapelmann ◽  
Kazimierz Madela ◽  
Michael Laue ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Blue Light ◽  
Spray Deposition ◽  
Argon Plasma ◽  
Biological Indicators ◽  
Low Pressure ◽  
Content Type ◽  
Testing Procedures ◽  
Bacterial Endospores ◽  
Surface Decontamination

ABSTRACTNovel decontamination technologies, including cold low-pressure plasma and blue light (400 nm), are promising alternatives to conventional surface decontamination methods. However, the standardization of the assessment of such sterilization processes remains to be accomplished. Bacterial endospores of the generaBacillusandGeobacillusare frequently used as biological indicators (BIs) of sterility. Ensuring standardized and reproducible BIs for reliable testing procedures is a significant problem in industrial settings. In this study, an electrically driven spray deposition device was developed, allowing fast, reproducible, and homogeneous preparation ofBacillus subtilis168 spore monolayers on glass surfaces. A detailed description of the structural design as well as the operating principle of the spraying device is given. The reproducible formation of spore monolayers of up to 5 × 107spores per sample was verified by scanning electron microscopy. Surface inactivation studies revealed that monolayered spores were inactivated by UV-C (254 nm), low-pressure argon plasma (500 W, 10 Pa, 100 standard cubic cm per min), and blue light (400 nm) significantly faster than multilayered spores were. We have thus succeeded in the uniform preparation of reproducible, highly concentrated spore monolayers with the potential to generate BIs for a variety of nonpenetrating surface decontamination techniques.

scholarly journals The kinetics of inactivation of the rod phototransduction cascade with constant Ca2+i.

1996 ◽  
Vol 107 (1) ◽  
pp. 19-34 ◽  
Author(s):  
A Lyubarsky ◽  
S Nikonov ◽  
E N Pugh
Keyword(s):  
G Protein ◽  
Time Constant ◽  
Inactivation Kinetics ◽  
First Order ◽  
Successful Model ◽  
Ringer’S Solution ◽  
Rhodopsin Kinase ◽  
Solution Bathing ◽  
Kinetics Of ◽  
Phototransduction Cascade

A rich variety of mechanisms govern the inactivation of the rod phototransduction cascade. These include rhodopsin phosphorylation and subsequent binding of arrestin; modulation of rhodopsin kinase by S-modulin (recoverin); regulation of G-protein and phosphodiesterase inactivation by GTPase-activating factors; and modulation of guanylyl cyclase by a high-affinity Ca(2+)-binding protein. The dependence of several of the inactivation mechanisms on Ca2+i makes it difficult to assess the contributions of these mechanisms to the recovery kinetics in situ, where Ca2+i is dynamically modulated during the photoresponse. We recorded the circulating currents of salamander rods, the inner segments of which are held in suction electrodes in Ringer's solution. We characterized the response kinetics to flashes under two conditions: when the outer segments are in Ringer's solution, and when they are in low-Ca2+ choline solutions, which we show clamp Ca2+i very near its resting level. At T = 20-22 degrees C, the recovery phases of responses to saturating flashes producing 10(2.5)-10(4.5) photoisomerizations under both conditions are characterized by a dominant time constant, tau c = 2.4 +/- 0.4 s, the value of which is not dependent on the solution bathing the outer segment and therefore not dependent on Ca2+i. We extended a successful model of activation by incorporating into it a first-order inactivation of R*, and a first-order, simultaneous inactivation of G-protein (G*) and phosphodiesterase (PDE*). We demonstrated that the inactivation kinetics of families of responses obtained with Ca2+i clamped to rest are well characterized by this model, having one of the two inactivation time constants (tau r* or tau PDE*) equal to tau c, and the other time constant equal to 0.4 +/- 0.06 s.

Potential Bacillus subtilis α-Amylase-Based Time-Temperature Integrators To Evaluate Pasteurization Processes

1996 ◽  
Vol 59 (3) ◽  
pp. 261-267 ◽  
Author(s):  
A. VAN LOEY ◽  
M. HENDRICKX ◽  
L. LUDIKHUYZE ◽  
C. WEEMAES ◽  
T. HAENTJENS ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Environmental Conditions ◽  
Thermal Inactivation ◽  
Enzymic Activity ◽  
Inactivation Kinetics ◽  
Response Property ◽  
Integrated Processing ◽  
Target Attributes ◽  
Kinetics Of ◽  
Residual Heat

Thermal inactivation kinetics of Bacillus subtilis α-amylase (BSA) in different environmental conditions was studied by performing isothermal experiments. As a response property, residual enzymic activity and residual heat of enzyme deterioration were chosen. A comparison of processing values determined from the read-out of a system with actual integrated processing values revealed the potentials of these systems as time-temperature integrators to be used in the pasteurization domain (temperatures of 70 to 100°C) for target attributes with z-values ranging from 6 to l2°C.

scholarly journals Purification, characterization and thermal inactivation kinetics of a non-regioselective thermostable lipase from a genotypically identified extremophilic Bacillus subtilis NS 8

2011 ◽  
Vol 28 (6) ◽  
pp. 738-745 ◽  
Author(s):  
Akanbi Taiwo Olusesan ◽  
Liyana Kamaruzaman Azura ◽  
Bita Forghani ◽  
Fatimah Abu Bakar ◽  
Abdul Karim Sabo Mohamed ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Thermal Inactivation ◽  
Inactivation Kinetics ◽  
Thermostable Lipase ◽  
Kinetics Of

scholarly journals Chlorine inactivation of hepatitis E virus and human adenovirus 2 in water

2014 ◽  
Vol 12 (3) ◽  
pp. 436-442 ◽  
Author(s):  
Rosina Girones ◽  
Anna Carratalà ◽  
Byron Calgua ◽  
Miquel Calvo ◽  
Jesús Rodriguez-Manzano ◽  
...  
Keyword(s):  
Hepatitis E Virus ◽  
Free Water ◽  
Human Adenovirus ◽  
Hepatitis E ◽  
Oral Route ◽  
Inactivation Kinetics ◽  
Common Source ◽  
Log Reduction ◽  
Chlorine Disinfection ◽  
Kinetics Of

Hepatitis E virus (HEV) is transmitted via the fecal–oral route and has been recognized as a common source of large waterborne outbreaks involving contaminated water in developing countries. Thus, there is the need to produce experimental data on the disinfection kinetics of HEV by chlorine in water samples with diverse levels of fecal contamination. Here, the inactivation of HEV and human adenovirus C serotype 2 (HAdV2), used as a reference virus, was monitored using immunofluorescence and quantitative reverse transcription polymerase chain reaction (RT-qPCR) assays. HEV has been shown to be susceptible to chlorine disinfection and presented equivalent kinetics to human adenoviruses. The C(t) values observed for a 2-log reduction of HEV were 0.41 in buffered demand-free water and 11.21 mg/L × min in the presence of 1% sewage. The results indicate that the inactivation kinetics of HEV and HAdV2 are equivalent and support the use of chlorine disinfection as an effective strategy to control HEV waterborne transmission.

Sporicidal Activity of Chemical Germicides on Bacillus subtilis Spores Under Various Conditions

1994 ◽  
Vol 77 (1) ◽  
pp. 53-57 ◽  
Author(s):  
James W Danielson ◽  
James T Peeler ◽  
Gordon S Oxborrow
Keyword(s):  
Bacillus Subtilis ◽  
Chlorine Dioxide ◽  
Peracetic Acid ◽  
Bovine Serum ◽  
Hard Water ◽  
Soft Water ◽  
Initial Concentration ◽  
Log Reduction ◽  
Time Required ◽  
Intended Use

Abstract Sporicidal tests were conducted on chemical germicides used for reprocessing hemodialyzers. The germicides that were tested for sporicidal activity contain some of the same active ingredients as many other commercial germicides, although instructions for dilution and exposure time may vary according to intended use. Cidex-Dialyzer™ (glu-taraldehyde), formaldehyde, Renalin™ (peracetic acid), and RenNew-D™ (chlorine dioxide) were each tested under the following conditions: at 50, 100, and 150% of the recommended concentration in soft water at 22°C; and at 1× the recommended concentration in soft water at 26.7°C, in hard water at 22°C, and in hard water containing 5% bovine serum at 22°C. Sporicidin-HD™ (glutaraldehyde–phenol) was tested only at the recommended concentration in soft water at 22°C. The time required for a 2-log reduction in the initial concentration of spores ranged from 1.8 min for Renalin at 150% of the recommended concentration to 26.4 h for formaldehyde in hard water containing 5% bovine serum. Cidex-Dialyzer at 50% of the recommended concentration and Sporicidin-HD at the recommended concentration were ineffective against Bacillus subtilis var. niger spores. The sporicidal activities of RenNew-D and formaldehyde were greatly reduced when bovine serum was added to hard water. Renalin had the highest sporicidal activity and was the least affected by each of the conditions tested.

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