Reduction Of Spores Research Articles

Indoor Airborne Spore Levels Before and After Healthy Homes Education and Remediation

RationaleAsthmatic children are often sensitization to airborne fungi yet many live in homes containing poor indoor air quality (IAQ). To examine the reduction in airborne spores at the beginning and after 6 months enrolment in a Healthy Homes program the following studies were conducted.MethodsHomes enrolled in this project contained at least one child with asthma. Homes were evaluated for indoor and outdoor environmental conditions related to the maintenance of IAQ at the time of enrolment and after 6 months of participation in a healthy homes program. After enrolment, residents of these homes received education on maintaining a safe and healthy home along with assistance in remediating unsafe or unhealthy IAQ conditions in the home. Air collections were taken using a BioAire™ Model B520 spore trap both before and after education/remediation at two locations outside the home and at 5 locations inside the home. Air collections were evaluated microscopically for commonly identified spores.ResultsResults from the first 10 homes to fully complete the study indicate the major fungal spores present include Cladosporium (before 97% of collections; after 90% of collections); Aspergillus/Penicillium (87%/75%); Alternaria (35%/45%) and Stachybotrys (24%/6%). Overall spore reductions in the child's bedroom for these 10 homes included Stachybotrys (100%), Aspergillus/Penicillium (55%). Mean total indoor spore levels were reduced from 24% of outdoor ambient levels before the healthy homes program to 16% of outdoor ambient levels at completion.ConclusionsHealthy homes education along with remediation for unsafe or unhealthy conditions resulted in substantial reduction in airborne fungal spore exposure. RationaleAsthmatic children are often sensitization to airborne fungi yet many live in homes containing poor indoor air quality (IAQ). To examine the reduction in airborne spores at the beginning and after 6 months enrolment in a Healthy Homes program the following studies were conducted. Asthmatic children are often sensitization to airborne fungi yet many live in homes containing poor indoor air quality (IAQ). To examine the reduction in airborne spores at the beginning and after 6 months enrolment in a Healthy Homes program the following studies were conducted. MethodsHomes enrolled in this project contained at least one child with asthma. Homes were evaluated for indoor and outdoor environmental conditions related to the maintenance of IAQ at the time of enrolment and after 6 months of participation in a healthy homes program. After enrolment, residents of these homes received education on maintaining a safe and healthy home along with assistance in remediating unsafe or unhealthy IAQ conditions in the home. Air collections were taken using a BioAire™ Model B520 spore trap both before and after education/remediation at two locations outside the home and at 5 locations inside the home. Air collections were evaluated microscopically for commonly identified spores. Homes enrolled in this project contained at least one child with asthma. Homes were evaluated for indoor and outdoor environmental conditions related to the maintenance of IAQ at the time of enrolment and after 6 months of participation in a healthy homes program. After enrolment, residents of these homes received education on maintaining a safe and healthy home along with assistance in remediating unsafe or unhealthy IAQ conditions in the home. Air collections were taken using a BioAire™ Model B520 spore trap both before and after education/remediation at two locations outside the home and at 5 locations inside the home. Air collections were evaluated microscopically for commonly identified spores. ResultsResults from the first 10 homes to fully complete the study indicate the major fungal spores present include Cladosporium (before 97% of collections; after 90% of collections); Aspergillus/Penicillium (87%/75%); Alternaria (35%/45%) and Stachybotrys (24%/6%). Overall spore reductions in the child's bedroom for these 10 homes included Stachybotrys (100%), Aspergillus/Penicillium (55%). Mean total indoor spore levels were reduced from 24% of outdoor ambient levels before the healthy homes program to 16% of outdoor ambient levels at completion. Results from the first 10 homes to fully complete the study indicate the major fungal spores present include Cladosporium (before 97% of collections; after 90% of collections); Aspergillus/Penicillium (87%/75%); Alternaria (35%/45%) and Stachybotrys (24%/6%). Overall spore reductions in the child's bedroom for these 10 homes included Stachybotrys (100%), Aspergillus/Penicillium (55%). Mean total indoor spore levels were reduced from 24% of outdoor ambient levels before the healthy homes program to 16% of outdoor ambient levels at completion. ConclusionsHealthy homes education along with remediation for unsafe or unhealthy conditions resulted in substantial reduction in airborne fungal spore exposure. Healthy homes education along with remediation for unsafe or unhealthy conditions resulted in substantial reduction in airborne fungal spore exposure.

Effect of processing parameters on inactivation of Bacillus cereus spores in milk using pulsed electric fields

The inactivation of Bacillus cereus spores in milk by treatment using pulsed electric fields (PEF) was studied. The effects of the electric field, temperature, number of pulses, pulse width, frequency and nisin concentration were tested in skim and whole milk. Results showed high resistance of spores to PEF alone; mild thermal treatment (40 °C) applied together with PEF had an antagonistic effect, and treatment at 50 °C enhanced spore death. Skim milk was a better medium than whole milk for inactivation; stronger thermal treatment (65 °C) together with PEF achieved a slight increase in spore reduction. The effect of pulse width was not consistent. Addition of nisin (50 IU mL−1) was synergistically effective (40 kV cm−1, 144 pulses, 65 °C), reducing spore count (by 3.6 log) in skim milk. Regardless of the severity of the treatment, spores showed resistance to the different processing variables.

MODELING THE THERMAL RESISTANCE OF CLOSTRIDIUM SPOROGENES SPORES UNDER DIFFERENT TEMPERATURE, pH AND NACl CONCENTRATIONS

ABSTRACTThe objective of this study was to examine the effects of temperature (101–121C), pH value (5.5–6.5) and concentration of sodium chloride (2–6%) on the heat resistance of Clostridium sporogenes spores under laboratory conditions. The inactivation curves of spore reduction from 1010 to 105 cfu/mL were fitted by Weibull frequency distribution model, and the primary fitting equations were obtained with R2 > 0.90. Moreover, the inactivation parameters δ and p of Weibull functions were modeled using a quadratic polynomial equation of response surface model (RSM). Mathematical evaluation demonstrated that the standard error of prediction (%SEP) obtained by RSM was 11.826 and 6.735% for model establishing δ and p, respectively, and 1.390 and 9.907% for model validation, respectively. The root mean square error was less than 0.05 for δ and p. Both the bias factor and accuracy factor were within acceptable range for model establishing and validation. Therefore, RSM provides a useful and accurate method of fitting the effects of experimental conditions on the thermal resistance of C. sporogenes spores, and could be referenced to ensure food safety with respect to C. sporogenes spores control.PRACTICAL APPLICATIONSWeibull frequency distribution model could be used for establishing nonlinear heat resistance models of Clostridium sporogenes spores under laboratory media conditions. The interacting effects of temperature, pH and NaCl concentration might be applied together for inactivating C. sporogenes spores growth in the food, and response surface model could be referenced to ensure food safety with respect to C. sporogenes spores control. Food producers would depend on these models for the decision‐making of food safety after established models are validated under real food environment.

Promoting Bacillus cereus spore germination for subsequent inactivation by mild heat treatment.

Sublethal heat treatment may activate dormant spores and thereby potentiate the conversion of spores to vegetative cells. As the germinated spore is known to possess lower heat resistance than its dormant counterpart, it has been postulated that double heat treatment, i.e., spore heat activation followed by germination and then by heat inactivation, can be used to control spores in foods. Production of refrigerated processed foods of extended durability often includes more than one heat treatment of the food components. This work simulates conventional heat treatment procedures and evaluates double heat treatment as a method to improve spore control in model food matrixes of meat broth and cream sauce. Bacillus cereus NVH 1230-88 spores were supplemented in food model matrixes and heat activated at 70°C and then heat inactivated at 80 or 90°C. The samples were held at 29 to 30°C for 1 h between primary and secondary heat treatments, to allow spore germination. Nutrients naturally present in the food matrixes, e.g., amino acids and inosine, could act as germinants that induce germination. The levels of germinants could be too low to produce effective germination within 1 h. Following primary heat treatment, some samples were therefore supplemented with a combination of L-alanine and inosine, a germinant mixture known to be effective for B. cereus spores. In both matrixes, a combination of double heat treatment (heat activation, germination, and inactivation) and addition of germinants gave a reduction in spore counts equivalent to or greater than that obtained with a single heat treatment for 12 min at 90°C. Addition of germinants was essential to induce effective germination in cream sauce during 1 h at 29 to 30°C, and germinants were therefore a crucial supplement to obtain an effect of double heat treatment in this matrix. These data will be valuable when setting up temperature-time-germinant combinations for an optimized spore reduction in mild-heat-treated foods.

Scientific Opinion on On‐site treatment of pig carcasses

EFSA's Scientific Panel on Biological Hazards (BIOHAZ) was asked for a scientific opinion on an alternative method for processing Category (Cat) 2 Animal By-Products (ABP). The materials to be treated are placentas and fallen pigs; this implies that the animals died due to a disease, which in most cases was not properly diagnosed. The target parameters are: i) particle size less than 150 mm and ii) heating for 10–12 hours at 100°C. The end-product obtained is mixed with pig slurry and used as an organic fertiliser. According to the legislation in force, before being used as an organic fertiliser, Cat. 2 material should be treated with a sterilisation process (i.e. 133°C / 20 min / 3 bars / 50 mm particle size). The most resistant hazards identified by the applicant as target to demonstrate the risk reduction are spores of pathogenic clostridia. Due to uncertainty on the cause of the animals’ death, the presence of more resistant hazards cannot be considered negligible. The sterilisation process defined in the current legislation is able to minimise the risks due to unidentified agents, such as Bacillus anthracis and TSE agents. The BIOHAZ Panel concluded that the process proposed was not properly validated experimentally under real scale conditions. In theory, it should permit a high degree of reduction of spores of pathogenic clostridia but because of several uncertainties (i.e. water evaporation, fat protective effect and particle size) it is not certain that the values of the parameters used in the theoretical calculations would apply in practice. Moreover, the proposed alternative method cannot be considered equivalent to the sterilisation process defined in the current legislation. This would be particularly relevant in the case of extremely heat resistant spores being present in the material to be treated.

THE REMOVAL OF PSYCHROTROPIC SPORES FROM MILK PROTEIN ISOLATE FEEDS USING TUBULAR CERAMIC MICROFILTERS

ABSTRACTThe application of microfiltration (MF) to remove spores from high solids content (5–15 wt %) Milk protein isolate (MPI) solutions are reported as a possible alternative process to pasteurization. MPI feeds were inoculated with Bacillus mycoides spores as a safer alternative to Bacillus cereus found in dairy feeds. The protocol used led to successful filtration outcomes for 5 and 10 wt % feeds, with the most encouraging result for 10 wt % found using a 12.0‐µm membrane and 1.4 m/s cross‐flow velocity. This produced a flux of 123 L m2/hr (LMH), a 90% protein transmission and a 2.6 log spore reduction. The filtration of 15 wt % MPI solutions proved more challenging. The best set of results for this feed was also obtained using a 12.0‐µm membrane at 1.4 m/s, producing a flux of 27 LMH, 96.5% protein transmission and a 2.1 log spore reduction. These results indicate that large pore ceramic MF may be a suitable technology to replace or augment pasteurization for high solids content dairy feeds.PRACTICAL APPLICATIONSMilk and other dairy products are highly nutritious media, in which microorganisms can cause spoilage. The use of microfiltration (MF) as an alternative to pasteurization to reduce the microbial load of raw skim milk is a well‐established technology being used to produce commercially available products such as Cravendale® milk. However, its application in reducing bacteria from highly viscous dairy‐based solutions has not become established because of issues of low flux and high fouling tendency. The novelty in this study is the filtration of high solids content (up to 15 wt %) MPI streams to reduce microbial load.MF represents an attractive alternative processing technique to pasteurization for the treatment of dairy products. Whereas pasteurization only destroys heat‐sensitive spoilage and pathogenic bacteria, MF is capable of removing all types of microorganisms including thermoduric and spore‐forming bacteria. Moreover, MF can be carried out using lower temperatures than those used during pasteurization.

Bacillus coagulans spore inactivation through the application of oregano essential oil and heat

The present study evaluated the effect of thermal (temperature) and thermochemical (temperature+oregano essential oil (EO)) inactivation of Bacillus coagulans spores in Nutrient Broth (NB) adjusted at 4°Brix and pH of 4.2. Thermal treatments included temperatures between 95 and 103°C. For thermochemical treatment, first temperature was fixed at 100°C and EO concentration varied between 250 and 1000μg/g. Thermochemical treatment significantly reduced the time needed to reduce a 6log level of spores compared to thermal treatment, for example around 1.4min with 400μg/g of EO. Then, EO concentration was fixed at 400μg/g and temperature varied between 90 and 100°C. Although the first results showed a faster spore reduction with 500μg/g, the fixed EO concentration was 400μg/g, since it represents a lower organoleptic impact and also a significant reduction in the spores’ resistance. For instance, at 97°C and 400μg/g, about 4.3min was needed to reduce the spores in 6log, without the EO this time was 5.0min. These findings indicate that oregano EO may be used to render B. coagulans spores more susceptible to the lethal effect of heat.

Carrier Tests To Assess the Effective Sporicidal Concentration of a Liquid Chemical Disinfectant for a Sanitization Program

The aim of the present investigation was to evaluate the microbial efficacy against highly resistant bacterial spores on different substrates using the lowest effective concentration of a market liquid sporicide based on peracetic acid. The validation was carried out following modified European regulatory agencies procedures or test methods and USP guidelines, employing carriers of materials usually treated with the sporicidal solution and present in grade A cleanrooms and spores of four different microorganisms: Bacillus subtilis and Clostridium sporogenes, both from the ATCC collection, and Bacillus cereus and Bacillus sphaericus as environmental isolates. A statistical evaluation of data was made to estimate the variance for different study conditions. The experiments highlighted that 70% suitable dilution of the ready-to-use peracetic acid solution was effective in both clean and dirty conditions, showing at least 2 log spore reduction after treatment. To obtain effective sporicidal action on the surfaces in cleanrooms it is sufficient to use a sporicidal solution with a ready-to-use concentration of 70% while ensuring a contact time of 10 min. In any case, the reduction of sporicide concentration ensures a high degree of disinfection and provides a consumption savings. Wide-spectrum disinfectants are used in the pharmaceutical industry for the decontamination of work surfaces and equipment, but these products have some degree of toxicity for operators. This work arises from the needs of pharmaceutical companies to find the lowest effective concentration of sanitizers in order to reduce toxicity to personnel. The sanitizer used in the study was a market liquid sporicide based on peracetic acid. When we started our work no similar studies were reported in the literature, so we took European regulatory agencies and USP guidelines as a starting point, employing carriers of hard, non-porous materials usually treated with the sporicidal solution and present in sterile rooms and spores of four different microorganisms. The experiments highlighted that it is sufficient to use a 70% sporicidal solution concentration with a contact time of 10 min to reduce the number of spores to acceptable values for medicinal production. The reduction of sporicide concentration both ensures a high degree of disinfection and provides a safer working environment and consumption savings.

Lab-Scale Assessment to Support Remediation of Outdoor Surfaces Contaminated with Bacillus anthracis Spores

Six liquid sporicides were evaluated for their ability to decontaminate common outdoor materials contaminated with spores of Bacillus anthracis Ames. Liquid aliquots containing spores of B. anthracis Ames were dried onto small coupons made of the outdoor materials: stainless steel, glass, aluminum, porcelain, granite, concrete, brick, asphalt, treated wood, and butyl rubber. Survivorship of spores was assessed following treatment of the coupons with each of six spray-applied sporicidal liquids (pH-amended Bleach, CASCAD™ SDF, Decon Green, EasyDECON® 200, Spor-Klenz® RTU, and Peridox® RTU). Results indicated that nonporous surfaces were easily decontaminated (all = 6 log10 reduction in viable spores) while porous surfaces, particularly concrete, asphalt, and treated wood, posed significant challenges for the sporicides tested. CASCAD™ SDF was the only sporicide tested that resulted in complete inactivation of spores on all materials. Overall, decontamination efficacy was highly dependent upon surface type, where generally higher efficacies were observed on nonporous materials for each sporicide. Results from this study will allow informed decisions to be made regarding selection of sporicides, based upon efficacy, to decontaminate outdoor surfaces contaminated with spores of Bacillus anthracis and therefore shorten the time and effort required to remediate following a bioterror incident.

Sterilization of Heat-Sensitive Silicone Implant Material by Low-Pressure Gas Plasma

In recent years, plasma treatment of medical devices and implant materials has gained more and more acceptance. Inactivation of microorganisms by exposure to ultraviolet (UV) radiation produced by plasma discharges and sterilization of medical implants and instruments is one possible application of this technique. The aim of this study was to evaluate the effectiveness of this sterilization technique on silicone implant material. Bacillus atrophaeus spores (10(6) colony-forming units [CFUs]) were sprayed on the surfaces of 12 silicone implant material samples. Four plasma sets with different gas mixtures (argon [Ar], argon-oxygen [Ar:O(2)], argon-hydrogen [Ar:H(2)] and argon-nitrogen [Ar:N(2)]) were tested for their antimicrobial properties. Post-sterilization mechanical testing of the implant material was performed in order to evaluate possible plasma-induced structural damage. The inductively coupled low-pressure plasma technique can achieve fast and efficient sterilization of silicone implant material without adverse materials effects. All four gas mixtures led to a significant spore reduction, and no structural damage to the implant material could be observed.

Efficacy of Chemical Preservatives to Control Perilla Rust

The rust fungi are biotrophic fungal pathogens that cause serious disease on Perilla leaves in Korea. The effect of some commonly used chemical preservatives (sorbic acid, D-sorbitol, propionic acid and benzoic acid) against Perilla rust was investigated in this study. Results of this investigation showed that all the preservatives were effective against Perilla rust except benzoic acid. There was no growth of rust spores on the Perilla leaves treated with 0.1% of preservative even after 21 days of preservation. However, 0.01% of preservative also showed remarkable reduction of rust spores on the Perilla leaves as compared to the control groups. Thus, the results of this study indicated that the chemical preservatives used might be useful to control the growth of rust fungi on Perilla leaves.

Quality and mold control of enriched white bread by combined radio frequency and hot air treatment

This study explored the application of radio frequency (RF) energy in conjunction with conventional hot air treatment to provide uniform heating for control of mold in pre-packaged bread loaf. A 6 kW, 27.12 MHz RF system was used to develop treatment protocols. The treatment parameters were selected based on minimum time–temperature conditions that were required for 4-log reduction of Penicillium citrinum spores while yielding acceptable bread quality. During combined RF and hot air treatments, the core and periphery of the bread loaf were heated together with almost the same heating rate. The maximum temperature difference within one bread slice was less than 5 °C. The moisture contents and water activities of RF treated samples first increased and then decreased compared to those of untreated samples, while firmness increased during the storage for both heat treated and untreated samples, yet the overall differences in sample qualities between RF treated bread samples and control were not significant. Because of better heating uniformity, much lower mean product temperature and shorter holding time were used for control of P. citrinum spores with combined RF and hot air treatment as compared to conventional heating alone. Heating bread to 58 °C or higher resulted in 4-log reduction of P. citrinum spores isolated from moldy bread. The storage life at room temperature (23 °C) was extended by 28 ± 2 days for the treated white bread.

Cleaning effectiveness of chlorine-free detergents for use on dairy farms

A method for evaluating cleaning effect based on Bacillus cereus spores was developed and tested in a model system designed to resemble actual farm conditions. A test rig with four removable sampling plates was mounted in a milk line. The plates were attached at the end of T-junctions protruding either 1·5 or 3-times the milk pipe diameter from the main loop to reflect different levels of cleaning difficulty. In each cleaning test, B. cereus spores were applied to the four sampling plates to simulate soil. A series of cleaning tests was conducted at 35, 45, 55 and 65°C with six commercial chlorine-free, alkaline detergents; three liquid and three powder-based products. A commercial alkaline detergent with chlorine, a sodium hydroxide solution, a sodium hydroxider/hypochlorite solution and pure water were also tested. Triplicate tests were performed with each cleaning solution, giving a total of 120 cleaning tests. The cleaning effect was evaluated by comparing the number of spores before and after cleaning. At all temperatures, the two chlorine-based cleaning solutions gave significantly greater reductions in B. cereus spores than the chlorine-free products. All six commercial chlorine-free, alkaline detergents generally gave similar cleaning effects, with no differences in the performance of powder-based and liquid forms. The mechanical spore reduction effect with water alone was greater (1·5-1·8 log-units) than the additional chemical effect of sodium hydroxide or chlorine-free detergents (0·5-1·2 log-units). The chlorine-based solutions had a considerably more powerful chemical effect (2-4 log-units depending on temperature). In general, an increase in cleaning solution temperature up to 55°C gave a greater reduction in spores. A further increase to 65°C did not improve cleaning effectiveness.

Cold Plasma Inactivation ofBacillus cereusandBacillus anthracis(Anthrax) Spores

Bacillus spores represent one of the most resistant organisms to conventional sterilization methods. This paper is focused on the inactivation of the spores of two Bacillus species, Bacillus cereus and Bacillus anthracis, using atmospheric-pressure dielectric-barrier-discharge (DBD) plasma. Spores treated in liquid or air-dried on a solid surface were effectively inactivated within 1 min of DBD plasma treatment at a discharge power of 0.3 W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Results of a series of model experiments show that neutral reactive oxygen species and UV radiation play a dominant role in the inactivation of spores. We also show that 45 s of the DBD plasma treatment of air-dried spores placed inside closed plastic or paper envelopes permits up to 7 log reduction of viable spores.

Treatment with chlorous acid to inhibit spores of Alicyclobacillus acidoterrestris in aqueous suspension and on apples

To test the efficacy of a chemical (chlorous acid) for reducing the numbers of viable Alicyclobacillus acidoterrestris spores in laboratory media and on apples. Alicyclobacillus acidoterrestris spores in aqueous suspension and on apple surfaces of four different cultivars were treated with 268 ppm chlorous acid. Treatment with 268 ppm chlorous acid sharply reduced the numbers of spores of A. acidoterrestris in laboratory media by 1.6, 4.3, and 7.0 log(10) reductions for 5, 10, and 15 min treatments, respectively. Chlorous acid also effectively reduced the spore load on apple surfaces. Alicyclobacillus acidoterrestris spore counts were significantly reduced by about 5 log(10) after 10 min treatment on four different apple cultivars ('Red Delicious', 'Golden Delicious',' Gala', and 'Fuji'). There was no synergistic effect on spore reduction when chlorous acid treatment was combined with heat. These results show that chlorous acid is highly efficacious against A. acidoterrestris spores on apple surfaces. Chlorous acid can be used as an alternative sanitizer of chlorine to control a major A. acidoterrestris contamination source in juice processing plants.

Efectividad del Acido Peracético sobre la reducción de la carga de Esporas de Mohos causantes de Pudrición Poscosecha de Frutas y Hortalizas

The objective of this work was to determine in vitro the effectiveness of peracetic acid on the load reduction of mould spores that are responsible for rotting in fruits and vegetables to evaluate its potential application to post-harvest control. Three concentrations of peracetic acid (0.05%, 0.1% and 0.3%) were used to evaluate its anti-fungal capacity against Alternaria Alternata, Fusarium graminearum, Aspergillus ochraceus, A. niger, A. flavus, Penicillium roqueforti and P. expansum. It was observed reduction of the load of spores using the lowest concentration. This effect was increased with a higher concentration of peracetic acid. It was extremely effective at a concentration of 0.3% against A. alternata, F. graminearum and A. ochraceus. It is concluded that the peracetic acid is a nonpolluting alternative treatment for post-harvest rotting control of fruits and vegetables

Neurodermitis und Psoriasis: Was bringt die stationäre Therapie im Hochgebirgsklima mehr?

Atopic dermatitis as well as psoriasis are characterized as common, chronic, often long lasting disorders of the cutis. In case of (a) a refractory out-patient therapy, (b) an acute severe exacerbation of skin lesions, (c) functional impairment of hands and feet, (d) suberythroderma or erythroderma, (e) complex topical as well as systemic treatment modalities, (f) complicating somatic or psychological co-morbidity, a referral to in-patient treatment at high altitude must be considered. The therapy at the Hochgebirgsklinik Davos (1,560 m above sea level) is characterized by application of natural-borne UV radiation all year round, missing house dust mite allergen, massive reduction of pollens and mycotic spores, improvement of skin perfusion as well as a reduction in itching (as compared to low altitude regions). Last but not least, silence and distance from home and company may show benefits for psychological and cutaneous well-being the 24-hour daily presence of dermatology experts, a broad armamentarium of topical and systemic treatment modalities as well as wide range of up-to-date diagnostic and therapeutic tools have to be further mentioned.

Silicon Oxide Permeation Barrier Coating and Plasma Sterilization of PET Bottles and Foils

AbstractThe results of silicon oxide permeation barrier coating and plasma sterilization are shown using a low‐pressure microwave plasma reactor system based on a Plasmaline antenna developed for the treatment of polyethylene terephthalate bottles and foils. The influence of the coating composition on the barrier properties is analyzed and a good correlation is found. The optimized barrier coatings are analyzed regarding coating defects, which are visualized by means of capacitively coupled oxygen plasma etching of the coated substrates. The capabilities of plasma sterilization are exemplarily demonstrated for spores of Bacillus atrophaeus allowing for a spore reduction according to today's regulations for aseptic food packaging.

Enhanced Decontamination ofBacillusSpores in a Simulated Drinking Water System by Germinant Addition

Contact with germinant solutions followed by commonly used disinfectants as a means to decontaminate Bacillus spores in a model drinking water system was investigated. Biofilms composed of indigenous water system bacteria were accumulated on materials commonly used for residential plumbing, polyvinyl chloride (PVC), and copper, in a continuously stirred tank reactor for controlled shear. Once the biofilms were established, Bacillus thuringiensis kurstaki or B. anthracis Sterne spores were added to the reactor. Pipe surfaces were studied for biofilm accumulation, spore adhesion, and disinfectant (chlorine and monochloramine) susceptibility before and after germinant (1 mM inosine and 8 mM L-alanine) addition. High disinfectant concentrations (up to 100 mg/L free chlorine and 10 mg/L monochloramine) yielded less than a 2 log10 reduction in biofilm-associated viable spores after 60 min. A 4 log10 reduction in the associated spores was observed when coupons were contacted with germinants (24 h) prior to sampling. Germinant contact followed by heat (50°C, 25 min) or disinfection resulted in a greater than 4 log10 reduction in the associated viable spores. Contact with germinants resulted in dramatically enhanced susceptibility of surface-associated spores to elevated water temperature and disinfectants.

Influence of pressurization rate and pressure pulsing on the inactivation of Bacillus amyloliquefaciens spores during pressure-assisted thermal processing.

Pressure-assisted thermal processing (PATP) is an emerging sterilization technology in which a combination of pressure (500 to 700 MPa) and temperature (90 to 120 degrees C) are used to inactivate bacterial spores. The objective of this study was to examine the role of pressurization rate and pressure pulsing in enhancing PATP lethality to the bacterial spore. Bacillus amyloliquefaciens TMW 2.479 spore suspensions were prepared in deionized water at three inoculum levels (1.1 x 10(9), 1.4 x 10(8), and 1.3 x 10(6) CFU/ml), treated at two pressurization rates (18.06 and 3.75 MPa/s), and held at 600 MPa and 105 degrees C for 0, 0.5, 1, 2, 3, and 5 min. Experiments were carried out using custom-fabricated, high-pressure microbial kinetic testing equipment. Single and double pulses with equivalent pressure-holding times (1 to 3 min) were investigated by using the spore suspension containing 1.4 x 10(8) CFU/ml. Spore survivors were enumerated by pour plating, using Trypticase soy agar after incubation at 32 degrees C for 2 days. During short pressure-holding times (< or = 2 min), PATP treatment with the slow pressurization rate provided enhanced spore reduction over that of the fast pressurization rate. However, these differences diminished with extended pressure-holding times. After a 5-min pressure-holding time, B. amyloliquefaciens population decreased about 6 log CFU/ml, regardless of pressurization rate and inoculum level. Double-pulse treatment enhanced PATP spore lethality by approximately 2.4 to 4 log CFU/ml, in comparison to single pulse for a given pressure-holding time. In conclusion, pressure pulsing considerably increases the efficacy of PATP treatment against bacterial spores. Contribution of pressurization rate to PATP spore lethality varies with duration of pressure holding.