Inactivation of Foodborne Bacteria Biofilms by Aqueous and Gaseous Ozone

In vitro effects of different ozone preparations on microorganisms responsible for endometritis in the mare

Infectious endometritis is considered one of the major causes of infertility and it can affect up to 60% of barren mares. It is characterized by the presence of one or more microorganisms in the reproductive tract and it is treated with the administration of antibiotics, ecbolic agents and uterine lavages. Ozone, thanks to its antimicrobial properties that are based on its high oxidative potential, could represent an effective alternative treatment for endometritis. The aim of this study was to test in vitro the bactericidal and fungicidal properties of different ozone formulations, either as gas (experiment 1) or dissolved in two liquid matrices (experiment 2), specifically distilled water or oil (Neozone 4000, Cosmoproject, Parma, Italy), onto 6 different species of microorganisms isolated from mares with clinical endometritis, namely Escherichia coli, Staphylococcus aureus, Streptococcus equi subsp. Zooepidemicus, Pseudomonas aeruginosa, Klebsiella pneumoniae and Candida albicans. In the first experiment, 3 clinical antibiotic-resistant strains per each species were exposed to different conditions: to O2O3 gas mixtures (15 and 40 μg/ml for 1, 3 and 5 min), to 100 % O2 or left untreated. The results showed a reduction of the microbial count of over 99,9% for every pathogen, time and concentration of O2O3 gas mixtures tested. Furthermore, gaseous ozone showed both a time-dependant effect (5 vs 3 vs 1 min of exposure) and a concentration-dependant effect (40 vs 15 μg/ml) at 1 and 3 min, while after 5 min no differences were observed. In the second experiment, minimum inhibitory concentration (MIC), and minimum bactericidal/fungicidal concentration (MBC, MFC) of ozonated distilled water and ozonated oil were evaluated. Ozonated oil showed a bactericidal/fungicidal activity against all the strains tested (MIC range 12.5-25 % v/v, MBC/MFC range 12.5-50 % v/v) while ozonated distilled water didn't show an observable antimicrobial effect, discouraging its use as an antimicrobial agent for the treatment of endometritis. The results of this in vitro study indicate that both gaseous ozone and ozonated oil exerted remarkable antimicrobial activities and are promising alternative treatments for infectious endometritis, even when caused by antibiotic-resistant bacteria, and encourage further experiments in an effort to scale down or even prevent the use of antibiotics in equine reproduction.

Gaseous ozone and ozonized mist in the control of Escherichia coli on 'Rama Forte' persimmon

This study aimed to evaluate the effectiveness of using two ozone applications (gaseous and mist) as a disinfection method for fresh persimmon. To test these sanitizers, in vitro and in vivo assays were performed, and the Escherichia coli was selected because it is a pathogen that causes foodborne diseases in humans. For in vitro experiments, a plate was inoculated with Escherichia coli strain ATCC 25922 and treated. For in vivo assays, persimmon fruit surface was inoculated with the bacteria and treated. For both assays, it was used 10,15,20,30,40 and 50 μL L-1 of gaseous ozone or ozonized mist for five minutes. The results demonstrated that the gas ozone application significantly reduced the growth of E. coli on the plate surface in vitro at doses of 30, 40 and 50 μL L-1 (with 0.83, 0.89 and 0.95 log CFU mL-1, respectively). The application of ozonized mist showed a significant reduction for 50 μL L-1 (with 1.28 log CFU g-1). And, for the in vivo assays, ozonized mist significantly reduced the number of bacteria on the persimmon surface, with a 1.57 log reduction, which was the largest for 40 μL L-1. Therefore, it is possible to conclude that the ozone application can contribute to the control of microorganisms present on fruit surfaces.

Ozonation for Pseudomonas paracarnis control: biofilm removal and preservation of chicken meat during refrigerated storage

Ozone has been studied to control microorganisms in food, as well as to control biofilm. In this context, the goals of this work were to determine the effect of ozonated water in the removal of Pseudomonas paracarnis biofilm and the effect of ozone gas and ozonated water on inactivating P. paracarnis in deboned chicken breast meat and its effect on product color. AISI 304 coupons were used as a surface for biofilm formation. The coupons were immerged into minimal medium for Pseudomonas inoculated with the P. paracarnis overnight culture (1% w/v) followed by incubation at 25 °C for 7 days. To obtain ozonized water, two different systems were used: system with microbubble generator (MB) and system with porous stone diffuser (PSD). The inlet ozone concentration was 19 mg/L and flow rate of 1 L/min. The coupons were subjected to ozonized water for 10 and 20 min. The chicken breast meat was exposed to gaseous ozone and ozonized water for 40 min. After the ozonation process, chicken meat samples were stored at 8 °C, for 5 days. More expressive removals of biofilm were obtained when using ozonized water obtained in the system with microbubble generator (MB for 20 min-reduction of 2.3 log cycles) and system with porous stone diffuser (PSD for 10 min-reduction of 2.7 log cycles; PSD for 20 min-reduction of 2.6 log cycles). The treatment of chicken meat with ozone gas resulted in lower counting of Pseudomonas, when compared with the control treatments and with ozonized water, both immediately after ozonation (day 1) and after 5 days of storage. The luminosity in the chicken meat samples treated with ozonized water was higher than that verified in the control treatments and with ozone gas, immediately after ozonation (day 1). A similar trend was observed in hue angle and color difference, in which the highest values were obtained for treatment with ozonized water. Based on the results obtained in this study, it was concluded that ozonated water can be used to remove P. paracarnis biofilm from stainless steel under static conditions and gaseous ozone is more efficient in the inactivation of P. paracarnis from chicken breast meat, when compared to ozonated water.

Biofilm formation under food-relevant conditions and sanitizers' tolerance of a Pseudomonas fluorescens group strain

AIMS

The aim of this study was to determine the biofilm-forming ability of a strain belonging to the Pseudomonas fluorescens group isolated from the dairy environment under food-relevant conditions. Moreover, the effects of commercial sanitizers against preformed biofilms were assessed both in terms of viability and structure.

METHODS AND RESULTS

The biofilms were formed on polystyrene, stainless steel (SS), and polytetrafluoroethylene (PTFE) in a wide range of temperatures (4-25°C) and were subjected to the action of 10 different sanitizers. The strain under study showed to be a strong biofilm-former regardless of temperature, particularly on polystyrene. The biofilms were mostly sensitive to chlorine and peracetic acid-based sanitizers. For some sanitizers (e.g. amphoteric), a relationship was observed between the material and the tolerance, while the temperature was not statistically significant. The formation of long-term biofilms on SS was also structurally affected by the temperature, showing microcolonies more irregular in shape and with lower cellularity at 4°C compared to 15°C, where the biofilm was more compact and with a high presence of EPS.

CONCLUSIONS

The strain belonging to the P. fluorescens group was shown to quickly adhere and form mature biofilm at temperatures and on materials relevant to the food sector; however, biofilms formed under different conditions were differently tolerant to disinfectants.

SIGNIFICANCE AND IMPACT OF THE STUDY

Findings from this study could provide a basis for developing targeted sanitation protocols in food plants.

The Use of Ozone Technology: An Eco-Friendly Method for the Sanitization of the Dairy Supply Chain

The dairy field has considerable economic relevance in the agri-food system, but also has the need to develop new 'green' supply chain actions to ensure that sustainable products are in line with consumer requirements. In recent years, the dairy farming industry has generally improved in terms of equipment and product performance, but innovation must be linked to traditional product specifications. During cheese ripening, the storage areas and the direct contact of the cheese with the wood must be carefully managed because the proliferation of contaminating microorganisms, parasites, and insects increases significantly and product quality quickly declines, notably from a sensory level. The use of ozone (as gas or as ozonated water) can be effective for sanitizing air, water, and surfaces in contact with food, and its use can also be extended to the treatment of waste and process water. Ozone is easily generated and is eco-sustainable as it tends to disappear in a short time, leaving no residues of ozone. However, its oxidation potential can lead to the peroxidation of cheese polyunsaturated fatty acids. In this review we intend to investigate the use of ozone in the dairy sector, selecting the studies that have been most relevant over the last years.

The Use of Ozone Technology to Control Microorganism Growth, Enhance Food Safety and Extend Shelf Life: A Promising Food Decontamination Technology

The need for microorganism control in the food industry has promoted research in food processing technologies. Ozone is considered to be a promising food preserving technique and has gained great interest due to its strong oxidative properties and significant antimicrobial efficiency, and because its decomposition leaves no residues in foods. In this ozone technology review, the properties and the oxidation potential of ozone, and the intrinsic and extrinsic factors that affect the microorganism inactivation efficiency of both gaseous and aqueous ozone, are explained, as well as the mechanisms of ozone inactivation of foodborne pathogenic bacteria, fungi, mould, and biofilms. This review focuses on the latest scientific studies on the effects of ozone in controlling microorganism growth, maintaining food appearance and sensorial organoleptic qualities, assuring nutrient contents, enhancing the quality of food, and extending food shelf life, e.g., vegetables, fruits, meat, and grain products. The multifunctionality effects of ozone in food processing, in both gaseous and aqueous form, have promoted its use in the food industries to meet the increased consumer preference for a healthy diet and ready-to-eat products, although ozone may present undesirable effects on physicochemical characteristics on certain food products at high concentrations. The combined uses of ozone and other techniques (hurdle technology) have shown a promotive future in food processing. It can be concluded from this review that the application of ozone technology upon food requires increased research; specifically, the use of treatment conditions such as concentration and humidity for food and surface decontamination.

Dry surface biofilms in the food processing industry: An overview on surface characteristics, adhesion and biofilm formation, detection of biofilms, and dry sanitization methods

Bacterial biofilm formation in low moisture food processing (LMF) plants is related to matters of food safety, production efficiency, economic loss, and reduced consumer trust. Dry surfaces may appear dry to the naked eye, however, it is common to find a coverage of thin liquid films and microdroplets, known as microscopic surface wetness (MSW). The MSW may favor dry surface biofilm (DSB) formation. DSB formation is similar in other industries, it occurs through the processes of adhesion, production of extracellular polymeric substances, development of microcolonies and maturation, it is mediated by a quorum sensing (QS) system and is followed by dispersal, leading to disaggregation. Species that survive on dry surfaces develop tolerance to different stresses. DSB are recalcitrant and contribute to higher resistance to sanitation, becoming potential sources of contamination, related to the spoilage of processed products and foodborne disease outbreaks. In LMF industries, sanitization is performed using physical methods without the presence of water. Although alternative dry sanitizing methods can be efficiently used, additional studies are still required to develop and assess the effect of emerging technologies, and to propose possible combinations with traditional methods to enhance their effects on the sanitization process. Overall, more information about the different technologies can help to find the most appropriate method/s, contributing to the development of new sanitization protocols. Thus, this review aimed to identify the main characteristics and challenges of biofilm management in low moisture food industries, and summarizes the mechanisms of action of different dry sanitizing methods (alcohol, hot air, UV-C light, pulsed light, gaseous ozone, and cold plasma) and their effects on microbial metabolism.

Removal of Pseudomonas fluorescens biofilms from pilot-scale food processing equipment using ozone-assisted cleaning-in-place

Biofilm formation in food processing environment and within equipment increases the risk of product spoilage and contamination with pathogens. Cleaning-in-place (CIP) operations are useful in removing soils and in sanitizing processing equipment, including eliminating biofilms. However, CIP is a resource-intensive process, particularly in the usage of chemical detergents, heat, and sanitizers. The current study was initiated to investigate the feasibility of integrating ozone into CIP operations to facilitate the elimination of Pseudomonas biofilm, with the long-term goal of decreasing the dependance on conventional cleaning and sanitizing reagents. To investigate integrating ozone into CIP, a robust biofilm of Pseudomonas fluorescens was developed on a pilot-scale food processing equipment after 2 days of incubation in 10% skim milk (skim milk-water mixture, 1:9 v/v) under stagnant conditions, followed by additional 5 days of circulation while feeding 10% fresh skim milk. CIP was applied using water prerinse at 22-25°C, alkaline cleaning with 0.2% potassium hydroxide at 50°C, and a final water rinse. These CIP operations reduced planktonic cell populations below the detection method's limit but did not fully remove P. fluorescens biofilm from either smooth or rough surfaces of the processing equipment. When the CIP process was followed by application of an aqueous ozone step (10 ppm for 10 min), the treatment reduced biofilm cell population, on smooth and rough surfaces, below the recovery method's detection limit (0.9 and 1.4 log CFU/ 100 cm², respectively). These findings demonstrate the utility of ozone-assisted CIP in eliminating microbial biofilms on processing equipment, but further research is needed to optimize the use of cleaning agents and the application of ozone.

The Use of Natural Methods to Control Foodborne Biofilms

Biofilms are large aggregates of various species of bacteria or other microorganisms tightly attached to surfaces through an intricate extracellular matrix. These complex microbial communities present quite the challenge in the food processing industry, as conditions such as raw meats and diverse food product content in contact with workers, drains, machinery, and ventilation systems, make for prime circumstances for contamination. Adding to the challenge is the highly resistant nature of these biofilm growths and the need to keep in mind that any antimicrobials utilized in these situations risk health implications with human consumption of the products that are being processed in these locations. For that reason, the ideal means of sanitizing areas of foodborne biofilms would be natural means. Herein, we review a series of innovative natural methods of targeting foodborne biofilms, including bacteriocins, bacteriophages, fungi, phytochemicals, plant extracts, essential oils, gaseous and aqueous control, photocatalysis, enzymatic treatments, and ultrasound mechanisms.

Recent advances in sterilization and disinfection technology: A review

Sterilization and disinfection of pollutants and microorganisms have been extensively studied in order to address the problem of environmental contamination, which is a crucial issue for public health and economics. Various form of hazardous materials/pollutants including microorganisms and harmful gases are released into the environment that enter into the human body either through inhalation, adsorption or ingestion. The human death rate rises due to various respiratory ailments, strokes, lung cancer, and heart disorders related with these pollutants. Hence, it is essential to control the environmental pollution by applying economical and effective sterilization and disinfections techniques to save life. In general, numerous forms of traditional physical and chemical sterilization and disinfection treatments, such as dry and moist heat, radiation, filtration, ethylene oxide, ozone, hydrogen peroxide, etc. are known along with advanced techniques. In this review we summarized both advanced and conventional techniques of sterilization and disinfection along with their uses and mode of action. This review gives the knowledge about the advantages, disadvantages of both the methods comparatively. Despite, the effective solution given by the advanced sterilization and disinfection technology, joint technologies of sterilization and disinfection has proven to be more effective innovation to protect the indoor and outdoor environments.

Pernicious Attitude of Microbial Biofilms in Agri-Farm Industries: Acquisitions and Challenges of Existing Antibiofilm Approaches

Biofilm is a complex matrix made up of extracellular polysaccharides, DNA, and proteins that protect bacteria against physical, chemical, and biological stresses and allow them to survive in harsh environments. Safe and healthy foods are mandatory for saving lives. However, foods can be contaminated by pathogenic microorganisms at any stage from farm to fork. The contaminated foods allow pathogenic microorganisms to form biofilms and convert the foods into stigmatized poison for consumers. Biofilm formation by pathogenic microorganisms in agri-farm industries is still poorly understood and intricate to control. In biofilms, pathogenic bacteria are dwelling in a complex manner and share their genetic and physicochemical properties making them resistant to common antimicrobial agents. Therefore, finding the appropriate antibiofilm approaches is necessary to inhibit and eradicate the mature biofilms from foods and food processing surfaces. Advanced studies have already established several emerging antibiofilm approaches including plant- and microbe-derived biological agents, and they proved their efficacy against a broad-spectrum of foodborne pathogens. This review investigates the pathogenic biofilm-associated problems in agri-farm industries, potential remedies, and finding the solution to overcome the current challenges of antibiofilm approaches.

Mask disinfection using atmospheric pressure cold plasma

OBJECTIVES

Mask usage has increased over the last few years due to the COVID-19 pandemic, resulting in a mask shortage. Furthermore, their prolonged use causes skin problems related to bacterial overgrowth. To overcome these problems, atmospheric pressure cold plasma was studied as an alternative technology for mask disinfection.

METHODS

Different microorganisms (Pseudomonas aeruginosa, Escherichia coli, Staphylococcus spp.), different gases (nitrogen, argon, and air), plasma power (90-300 W), and treatment times (45 seconds to 5 minutes) were tested.

RESULTS

The best atmospheric pressure cold plasma treatment was the one generated by nitrogen gas at 300 W and 1.5 minutes. Testing of breathing and filtering performance and microscopic and visual analysis after one and five plasma treatment cycles, highlighted that these treatments did not affect the morphology or functional capacity of the masks.

CONCLUSION

Considering the above, we strongly believe that atmospheric pressure cold plasma could be an inexpensive, eco-friendly, and sustainable mask disinfection technology enabling their reusability and solving mask shortage.

Understanding the Effect of Ozone on Listeria monocytogenes and Resident Microbiota of Gorgonzola Cheese Surface: A Culturomic Approach

The occurrence of Listeria monocytogenes on Gorgonzola cheese surface was reported by many authors, with risks arising from the translocation of the pathogen inside the product during cutting procedures. Among the novel antimicrobial strategies, ozone may represent a useful tool against L. monocytogenes contamination on Gorgonzola cheese rind. In this study, the effect of gaseous ozone (2 and 4 ppm for 10 min) on L. monocytogenes and resident microbiota of Gorgonzola cheese rind stored at 4 °C for 63 days was evaluated. A culturomic approach, based on the use of six media and identification of colonies by MALDI-TOF MS, was used to analyse variations of resident populations. The decrease of L. monocytogenes was less pronounced in ozonised rinds with final loads of ~1 log CFU/g higher than controls. This behaviour coincided with a lower maximum population density of lactobacilli in treated samples at day 28. No significant differences were detected for the other microbial determinations and resident microbiota composition among treated and control samples. The dominant genera were Candida, Carnobacterium, Staphylococcus, Penicillium, Saccharomyces, Aerococcus, Yarrowia, and Enterococcus. Based on our results, ozone was ineffective against L. monocytogenes contamination on Gorgonzola rinds. The higher final L. monocytogenes loads in treated samples could be associated with a suppressive effect of ozone on lactobacilli, since these are antagonists of L. monocytogenes. Our outcomes suggest the potential use of culturomics to study the ecosystems of complex matrices, such as the surface of mould and blue-veined cheeses.

Effect of gaseous ozone treatment on biofilm of dairy-isolated Pseudomonas spp. strains

Microbial biofilms existing in food industries have been implicated as important contamination sources of spoilage and pathogenic microorganisms in the finished products. Among the innovative strategies proposed to contrast biofilms in food environments, ozone is recognised as an environmentally friendly technology but there are few studies about its effect against bacterial biofilms. The objective of this study was to evaluate the effect of gaseous ozone (50 ppm for 6 h) in inhibition and eradication of biofilm formed by twenty-one dairyisolated Pseudomonas spp. strains. Before ozone treatments, all isolates were screened for biofilm formation according to a previously described method. Strains were then divided in four groups: weak, weak/moderate, moderate/strong, and strong biofilm producers based on the biofilm biomass value of each isolate determined using the optical density (OD - 595 nm). Inhibition treatment was effective on the strain (C1) belonging to the weak producers' group, on all strains classified as weak/moderate producers, on two strains (C8 and C12) belonging to the group of moderate/strong producers and on one strain (C13) classified as strong producer. Conversely, eradication treatments were ineffective on all strains tested, except for the strain C4 which reduced its biofilm-forming abilities after exposure to ozone gas. In conclusion, gaseous ozone may be used to enhance existing sanitation protocols in food processing environments, but its application alone not seems sufficient to contrast Pseudomonas spp. established biofilms.

Electrochemical Control of Biofilm Formation and Approaches to Biofilm Removal

This review deals with microbial adhesion to metal-based surfaces and the subsequent biofilm formation, showing that both processes are a serious problem in the food industry, where pathogenic microorganisms released from the biofilm structure may pollute food and related material during their production. Biofilm exhibits an increased resistance toward sanitizers and disinfectants, which complicates the removal or inactivation of microorganisms in these products. In the existing traditional techniques and modern approaches for clean-in-place, electrochemical biofilm control offers promising technology, where surface properties or the reactions taking place on the surface are controlled to delay or prevent cell attachment or to remove microbial cells from the surface. In this overview, biofilm characterization, the classification of bacteria-forming biofilms, the influence of environmental conditions for bacterial attachment to material surfaces, and the evaluation of the role of biofilm morphology are described in detail. Health aspects, biofilm control methods in the food industry, and conventional approaches to biofilm removal are included as well, in order to consider the possibilities and limitations of various electrochemical approaches to biofilm control with respect to potential applications in the food industry.

Disinfecting Action of Gaseous Ozone on OXA-48-Producing Klebsiella pneumoniae Biofilm In Vitro

Klebsiella pneumoniae is an emerging multidrug-resistant pathogen that can contaminate hospital surfaces in the form of a biofilm which is hard to remove with standard disinfectants. Because of biofilm resistance to conservative disinfectants, the application of new disinfection technologies is becoming more frequent. Ozone gas has antimicrobial activity but there is lack of data on its action against K. pneumoniae biofilm. The aim of this study was to investigate the effects and mechanisms of action of gaseous ozone on the OXA-48-procuding K. pneumoniae biofilm. A 24 h biofilm of K. pneumoniae formed on ceramic tiles was subsequently exposed to different concentrations of ozone during one and two hours to determine the optimal ozone concentration. Afterwards, the total bacteria count, total biomass and oxidative stress levels were monitored. A total of 25 ppm of gaseous ozone was determined to be optimal ozone concentration and caused reduction in total bacteria number in all strains of K. pneumoniae for 2.0 log₁₀ CFU/cm², followed by reduction in total biomass up to 88.15%. Reactive oxygen species levels significantly increased after the ozone treatment at 182% for the representative K. pneumoniae NCTC 13442 strain. Ozone gas in the concentration of 25 ppm caused significant biofilm reduction but did not completely eradicate the K. pneumoniae biofilm formed on ceramics. In conclusion, ozone gas has great potential to be used as an additional hygiene measure in joint combat against biofilm in hospital environments.

Advances, Applications, and Comparison of Thermal (Pasteurization, Sterilization, and Aseptic Packaging) against Non-Thermal (Ultrasounds, UV Radiation, Ozonation, High Hydrostatic Pressure) Technologies in Food Processing

Nowadays, food treatment technologies are constantly evolving due to an increasing demand for healthier and tastier food with longer shelf lives. In this review, our aim is to highlight the advantages and disadvantages of some of the most exploited industrial techniques for food processing and microorganism deactivation, dividing them into those that exploit high temperatures (pasteurization, sterilization, aseptic packaging) and those that operate thanks to their inherent chemical–physical principles (ultrasound, ultraviolet radiation, ozonation, high hydrostatic pressure). The traditional thermal methods can reduce the number of pathogenic microorganisms to safe levels, but non-thermal technologies can also reduce or remove the adverse effects that occur using high temperatures. In the case of ultrasound, which inactivates pathogens, recent advances in food treatment are reported. Throughout the text, novel discoveries of the last decade are presented, and non-thermal methods have been demonstrated to be more attractive for processing a huge variety of foods. Preserving the quality and nutritional values of the product itself and at the same time reducing bacteria and extending shelf life are the primary targets of conscious producers, and with non-thermal technologies, they are increasingly possible.

The Use of Ozone as an Eco-Friendly Strategy against Microbial Biofilm in Dairy Manufacturing Plants: A Review

Managing spoilage and pathogenic bacteria contaminations represents a major challenge for the food industry, especially for the dairy sector. Biofilms formed by these microorganisms in food processing environment continue to pose concerns to food manufacturers as they may impact both the safety and quality of processed foods. Bacteria inside biofilm can survive in harsh environmental conditions and represent a source of repeated food contamination in dairy manufacturing plants. Among the novel approaches proposed to control biofilm in food processing plants, the ozone treatment, in aqueous or gaseous form, may represent one of the most promising techniques due to its antimicrobial action and low environmental impact. The antimicrobial effectiveness of ozone has been well documented on a wide variety of microorganisms in planktonic forms, whereas little data on the efficacy of ozone treatment against microbial biofilms are available. In addition, ozone is recognized as an eco-friendly technology since it does not leave harmful residuals in food products or on contact surfaces. Thus, this review intends to present an overview of the current state of knowledge on the possible use of ozone as an antimicrobial agent against the most common spoilage and pathogenic microorganisms, usually organized in biofilm, in dairy manufacturing plants.

Plant-derived nanotherapeutic systems to counter the overgrowing threat of resistant microbes and biofilms

Since antiquity, the survival of human civilization has always been threatened by the microbial infections. An alarming surge in the resistant microbial strains against the conventional drugs is quite evident in the preceding years. Furthermore, failure of currently available regimens of antibiotics has been highlighted by the emerging threat of biofilms in the community and hospital settings. Biofilms are complex dynamic composites rich in extracellular polysaccharides and DNA, supporting plethora of symbiotic microbial life forms, that can grow on both living and non-living surfaces. These enforced structures are impervious to the drugs and lead to spread of recurrent and non-treatable infections. There is a strong realization among the scientists and healthcare providers to work out alternative strategies to combat the issue of drug resistance and biofilms. Plants are a traditional but rich source of effective antimicrobials with wider spectrum due to presence of multiple constituents in perfect synergy. Other than the biocompatibility and the safety profile, these phytochemicals have been repeatedly proven to overcome the non-responsiveness of resistant microbes and films via multiple pathways such as blocking the efflux pumps, better penetration across the cell membranes or biofilms, and anti-adhesive properties. However, the unfavorable physicochemical attributes and stability issues of these phytochemicals have hampered their commercialization. These issues of the phytochemicals can be solved by designing suitably constructed nanoscaled structures. Nanosized systems can not only improve the physicochemical features of the encapsulated payloads but can also enhance their pharmacokinetic and therapeutic profile. This review encompasses why and how various types of phytochemicals and their nanosized preparations counter the microbial resistance and the biofouling. We believe that phytochemical in tandem with nanotechnological innovations can be employed to defeat the microbial resistance and biofilms. This review will help in better understanding of the challenges associated with developing such platforms and their future prospects.

Case Series of Perioral Dermatitis Caused by Improper Use of Activated Oxygen

BACKGROUND

Activated oxygen is an important chemical for disinfecting surfaces. In the last 10 years, it has become increasingly common in continuous positive airway pressure (CPAP) devices.

OBJECTIVE

We sought to treat three cases of perioral dermatitis with concomitant use of CPAP devices.

METHODS

Three patients presented to the clinic with the complaint of a burning and stinging skin irritation involving the bilateral malar cheeks. Physical exam revealed symmetric, scaling, well-demarcated, erythematous, and slightly indurated areas of skin involving the bilateral malar cheeks. Corticosteroids were prescribed and provided little relief. In all three cases, the CPAP masks were worn within one hour of completing the sanitizing cycle. Each patient was instructed to lengthen the time between completion of the sanitizing cycle and application of the mask to a minimum of four hours.

RESULTS

All patients had resolution of their symptoms within two weeks of the modification, measured by subjective resolution and photodocumentation with resolution of erythema and scaling.

CONCLUSION

Ozone follows common gas laws such that its decay time can be considered in terms of half-life. Ozone requires approximately 1,524 minutes (25.4 hours) to decay one-half life when other factors are controlled. The activated oxygen containers are a fixed environment that could be causing increased O₃ residue on the CPAP machines. The residual O₃ reacts with the natural oils on the insdividual's skin to cause perioral dermatitis.

Effect of Gaseous Ozone on Listeria monocytogenes Planktonic Cells and Biofilm: An In Vitro Study

Among food-borne pathogens, Listeria monocytogenes continues to pose concerns to food business operators due to its capacity to form biofilm in processing environments. Ozone may be an eco-friendly technology to control microbial contaminations, but data concerning its effect on Listeria monocytogenes biofilm are still limited. In this study, the effect of gaseous ozone at 50 ppm on planktonic cells and biofilm of reference and food-related Listeria monocytogenes strains was evaluated. Ozone caused a reduction in microbial loads of 3.7 ± 0.4 and 3.9 ± 0.4 Log10 CFU/mL after 10 and 30 min, respectively. A complete inactivation of planktonic cells after 6 h of treatment was observed. Biofilm inhibition and eradication treatments (50 ppm, 6 h) resulted in a significant decrease of the biofilm biomass for 59% of the strains tested, whilst a slight dampening of live cell loads in the biofilm state was observed. In conclusion, gaseous ozone is not sufficient to completely counteract Listeria monocytogenes biofilm, but it may be useful as an additional tool to contrast Listeria monocytogenes free-living cells and to improve the existing sanitization procedures in food processing environments.

In Vitro Evaluation of Ozonated Water Treatment on the Viability of Eimeria Oocysts and Giardia Cysts from Water Buffaloes: A Proof-of-Concept Study

The aim of this proof-of-concept study was to evaluate the in vitro effects of ozonated water treatment on the viability of Eimeria oocysts and Giardia cysts isolated from naturally infected water buffaloes. Eimeria oocysts were divided into seven groups of six replicates that were treated with ozonated water at three ozone concentrations (0.5, 1, and 2 mg/L) and two contact times (five and ten minutes), and one group (negative control) that was exposed to non-treated water. Giardia cysts were divided into nine groups of six replicates and were treated with ozonated water at four ozone concentrations (0.1, 0.3, 0.5, and 1 mg/L) and two contact times (one and two minutes), while one group (negative control) was exposed to non-treated water. The results of the ozonated water treatment gave a 33% inhibition of the sporulation of Eimeria oocysts and rendered 96.3% of Giardia cysts non-viable, suggesting that ozonated water treatment could be a promising alternative sanitation technology to common conventional disinfectants for reducing intestinal protozoa infections in water buffaloes; though further in vitro and in vivo tests are needed.

Influence of Ozone on the Biochemical Composition of Birch Sap

Studies have shown that ozone is a good oxidizer and a strong disinfectant. There are many uses for ozone in the food industry, but there is relatively little information about the influence of ozone on biochemical composition and the capacity to reduce the number of microorganisms in birch sap. In this study, sap was ozonated at different intervals for 5 min (O3: 0.087 ± 0.009 mg L−1), 10 min, 15 min, 20 min, 25 min, or 30 min (O3: 0.99 ± 0.09 mg L−1). The parameters of the birch sap were studied immediately after the ozone treatment as well as during storage for seven days at 2 °C and for five days at 20 °C. The parameters of ozonated birch sap were compared with the parameters of fresh sap (control). The microbiological analysis included total bacterial count, lactic acid bacterial count, and yeast and mold count. Birch sap color, pH, titratable acidity, and ºBrix values were also determined. Evaluation of monosaccharides, sucrose, total sugars, and ascorbic acid was carried out in fresh sap as well as sap ozonated for 30 min, immediately after ozonation. The results show the statistical significance of the inactivation of microorganisms after treatment in most cases. The microorganism counts gradually reduced with increasing intervals of ozone treatment. The best results were obtained after 25 and 30 min of ozonation. Ozone treatment did not significantly influence the pH, titratable acidity, or °Brix statistically. Values of monosaccharides, sucrose, total sugars, and ascorbic acid were influenced within the margin of error. Ozone had a significant influence on the chroma and hue angle.

Ozone Treatments for Preserving Fresh Vegetables Quality: A Critical Review

Ozone is recognized as an antimicrobial agent for vegetables storage, washing, and processing. This strong disinfectant is now being used in the food industry. In this review, the chemical and physical properties of ozone, its generation, and factors affecting ozone processing efficiency were explained as well as recent regulatory developments in the food industry. By then selecting three vegetables, we show that ozone avoids and controls biological growth on vegetables, keeping their attractive appearance and sensorial qualities, assuring nutritional characteristics' retention and maintaining and increasing the shelf-life. In liquid solution, ozone can be used to disinfect processing water and vegetables, and in gaseous form, ozone helps to sanitize and preserve vegetables during storage. The multifunctionality of ozone makes it a promising food processing agent. However, if ozone is improperly used, it causes some deleterious effects on products, such as losses in their sensory quality. For an effective and a safe use of ozone, specific treatment conditions should be determined for all kinds of vegetables. In a last step, we propose highlighting the different essential characteristics of ozone treatment in order to internationally harmonize the data relating to the treatments carried-out.

Modeling the elimination of mature biofilms formed by Staphylococcus aureus and Salmonella spp. Using combined ultrasound and disinfectants

Biofilm formation by foodborne pathogens on food processing surfaces has contributed to numerous disease outbreaks and food recalls. We evaluated the following strategies for elimination of mature biofilm formed by Staphylococcus aureus and Salmonella spp. on stainless steel surfaces: acidic electrolyzed water (AEW), ozone water (OW), or ultrasound (40 kHz) alone, and combinations of ultrasound and disinfectants. The dynamics of elimination by combinations were determined using the Weibull and biphasic models. Treatment with AEW alone reduced the number of biofilm cells by approximately 3.0 log cfu/cm², whereas less than 0.8 log cfu/cm² of cells reduction was observed in biofilm exposed to OW or ultrasound alone, even with treatment for 20 min. The combination of AEW and ultrasound produced an obvious synergistic effect on biofilm reduction, achieving approximately 4.8 log cfu/cm² reduction in Salmonella spp. biofilm. Interestingly, the biphasic model was a better fit than the Weibull model for the elimination process of mature biofilm formed by both pathogens and subjected to a combination of ultrasound and AEW, as determined by smaller values of the statistical parameters RMSE and AIC, although both models could evaluate the dynamic processes. Our findings indicated that a combination of ultrasound and AEW could effectively reduce the biofilm formed by pathogens on food contact surfaces, and that the biphasic model could predict the number of residual cells after biofilm exposure to this intervention approach.

Spatiotemporal Distribution of the Environmental Microbiota in Food Processing Plants as Impacted by Cleaning and Sanitizing Procedures: the Case of Slaughterhouses and Gaseous Ozone

Microbial complexity and contamination levels in food processing plants heavily impact the final product fate and are mainly controlled by proper environmental cleaning and sanitizing. Among the emerging disinfection technologies, ozonation is considered an effective strategy to improve the ordinary cleaning and sanitizing of slaughterhouses. However, its effects on contamination levels and environmental microbiota still need to be understood. For this purpose, we monitored the changes in microbiota composition in different slaughterhouse environments during the phases of cleaning/sanitizing and ozonation at 40, 20, or 4 ppm. Overall, the meat processing plant microbiota differed significantly between secondary processing rooms and deboning rooms, with a greater presence of psychrotrophic taxa in secondary processing rooms because of their lower temperatures. Cleaning/sanitizing procedures significantly reduced the contamination levels and in parallel increased the number of detectable operational taxonomic units (OTUs), by removing the masking effect of the most abundant human/animal-derived OTUs, which belonged to the phylum Firmicutes Subsequently, ozonation at 40 or 20 ppm effectively decreased the remaining viable bacterial populations. However, we could observe selective ozone-mediated inactivation of psychrotrophic bacteria only in the secondary processing rooms. There, the Brochothrix and Pseudomonas abundances and their viable counts were significantly affected by 40 or 20 ppm of ozone, while more ubiquitous genera like Staphylococcus showed a remarkable resistance to the same treatments. This study showed the effectiveness of highly concentrated gaseous ozone as an adjunct sanitizing method that can minimize cross-contamination and so extend the meat shelf life.IMPORTANCE Our in situ survey demonstrates that RNA-based sequencing of 16S rRNA amplicons is a reliable approach to qualitatively probe, at high taxonomic resolution, the changes triggered by new and existing cleaning/sanitizing strategies in the environmental microbiota in human-built environments. This approach could soon represent a fast tool to clearly define which routine sanitizing interventions are more suitable for a specific food processing environment, thus limiting the costs of special cleaning interventions and potential product loss.

Comparative Genomic Analysis Reveals the Metabolism and Evolution of the Thermophilic Archaeal Genus Metallosphaera

Members of the genus Metallosphaera are widely found in sulfur-rich and metal-laden environments, but their physiological and ecological roles remain poorly understood. Here, we sequenced Metallosphaera tengchongensis Ric-A, a strain isolated from the Tengchong hot spring in Yunnan Province, China, and performed a comparative genome analysis with other Metallosphaera genomes. The genome of M. tengchongensis had an average nucleotide identity (ANI) of approximately 70% to that of Metallosphaera cuprina. Genes sqr, tth, sir, tqo, hdr, tst, soe, and sdo associated with sulfur oxidation, and gene clusters fox and cbs involved in iron oxidation existed in all Metallosphaera genomes. However, the adenosine-5'-phosphosulfate (APS) pathway was only detected in Metallosphaera sedula and Metallosphaera yellowstonensis, and several subunits of fox cluster were lost in M. cuprina. The complete 3-hydroxypropionate/4-hydroxybutyrate cycle and dicarboxylate/4-hydroxybutyrate cycle involved in carbon fixation were found in all Metallosphaera genomes. A large number of gene family gain events occurred in M. yellowstonensis and M. sedula, whereas gene family loss events occurred frequently in M. cuprina. Pervasive strong purifying selection was found acting on the gene families of Metallosphaera, of which transcription-related genes underwent the strongest purifying selection. In contrast, genes related to prophages, transposons, and defense mechanisms were under weaker purifying pressure. Taken together, this study expands knowledge of the genomic traits of Metallosphaera species and sheds light on their evolution.

Biocidal Effectiveness of Selected Disinfectants Solutions Based on Water and Ozonated Water against Listeria monocytogenes Strains

The aim of this study was to compare the biocidal effectiveness of disinfectants solutions prepared with ozonated and non-ozonated water against Listeria monocytogenes. Six L. monocytogenes strains were the research material (four isolates from food: meat (LMO-M), dairy products (LMO-N), vegetables (LMO-W), and fish (LMO-R); one clinical strain (LMO-K) and reference strain ATCC 19111). The evaluation of the biocidal effectiveness of disinfectant solutions (QAC-quaternary ammonium compounds; OA-oxidizing agents; ChC-chlorine compounds; IC-iodine compounds; NANO-nanoparticles) was carried out, marking the MBC values. Based on the obtained results, the effectiveness coefficient (A) were calculated. The smaller the A value, the greater the efficiency of disinfection solutions prepared on the basis of ozonated versus non-ozonated water. Ozonated water showed biocidal efficacy against L. monocytogenes. Among tested disinfectentants, independent on type of water used for preparation, the most effective against L. monocytogenes were: QAC 1 (benzyl-C12-18-alkydimethyl ammonium chlorides) (1.00 × 10-5-1.00 × 10-4 g/mL) in quaternary ammonium compounds, OA 3 (peracetic acid, hydrogen peroxide, bis (sulphate) bis (peroxymonosulfate)) (3.08 × 10-4 -3.70 × 10-3 g/mL) in oxidizing agents, ChC 1 (chlorine dioxide) (5.00 × 10-8 -7.00 × 10-7 g/mL) in chlorine compounds, IC 1 (iodine) (1.05-2.15 g/mL) in iodine compounds, and NANO 1 (nanocopper) (1.08 × 10-4 - 1.47 × 10-4 g/mL) in nanoparticles. The values of the activity coefficient for QAC ranged from 0.10 to 0.40, for OA-0.15-0.84, for ChC-0.25-0.83, for IC-0.45-0.60, and for NANO-0.70-0.84. The preparation of disinfectants solution on the basis of ozonated water, improved the microbicidal efficiency of the tested disinfectant, especially the quaternary ammonium compounds. An innovative element of our work is the use of ozonated water for the preparation of working solutions of the disinfection agents. Use ozonated water can help to reduce the use of disinfectant concentrations and limit the increasing of microbial resistance to disinfectants. This paper provides many new information to optimize hygiene plans in food processing plants and limit the spread of microorganisms such as L. monocytogenes.