Progress 02/01/23 to 01/31/24
Outputs
Target Audience:Target audiences reached by this project includes UV systems manufacturers and designers (Trojan technologies, Aquafine Corporation, Sarin energy), regulatory agencies (FDA, USDA), food companies (Unique Food solutions), faculty (research, extension) and graduate students. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The Post-doctoral fellow was enrolled in a grant writing workshop at TSU, sponsered programs office. The graduate students have been enrolled in a Ideator program at Vanderbilt University where they will learn to pitch ideas to investors. This is a great apporunity for the students. In addition, the students will enroll in NSF ICORP program in fall to develop business skills. The principal aim of the Mid-South Hub is to cultivate the generation of deep technology ventures that arise from the research and invention activities at regionally localized institutions of higher education (IHEs) and US National Laboratories. The programmatic purpose of the Mid-South Hub is to develop best practices as a scholarly incubator that informs future NSF programmatic investments using data driven approaches. A graduate student was sent to a training worshop (virology)at Meharry Medical School, Nashville TN. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?The last finding in our investigation was the inherited limitation of the analytical methods (microbial plating) to high concentration which previously authenticated for liquid solution were usual microbial infection used to be estimated by order of 7-10 logs. However, in the air environment the aerosolization infection is in order 1-2 logs and the plating methodfailed to detect viable comcentration. We aim to developappropriate analytical techniques for aerosolization.A combination of fluorescence microscopy, confocal microscopy, and flow cytometry will be implemented to further investigate and obtain intrinsic characteristics of the bacteria and viruses. This approach will assist indeterminingthe UV rate constant for microorganisms, linking their inactivation efficiency to the UV-C dose.
Impacts
What was accomplished under these goals?
The application of LED Ultraviolet Germicidal Irradiation (UVGI) technology is being investigated. UVGI works by utilizing short-wave ultraviolet energy (UVC, 200-280 nm) to disrupt the DNA and RNA of viral, bacterial, and fungal organisms, preventing their replication and transmission. Despite its promising potential, the understanding of aerosols-UVGI systems, particularly in terms of their operational mechanisms, design of bench top system, and practical applications, remains extremely limited . To bridge this knowledge gap, our research objectives and goals include:Optimizing the Aerosol UVGI System: We aim to determine the essential parameters for an effective UVGI design. This includes analyzing the LED lamp output, understanding the UV dose-response behavior of target microbes, and assessing both the inactivation performance and energy efficiency of the system.Environmental Impact Analysis: Investigating how environmental factors such as air velocity, temperature, and humidity influence the UVGI system. The goal is to refine the system design for optimal performance under various environmental conditions. Air quality in food processing facilities is a critical concern, especially considering the potential presence of pathogenic and spoilage micro-organisms, responsible for food contamination (e.g., Listeria, E. coli, and Salmonella). These pathogens are typically transmitted via droplets, contact, and airborne routes or during cleaning and CIP operation. Our project focuses on engineering controls to mitigate this risk of micro-organisms. We propose the use of UVGI treatment for air disinfection. While the integration of UV systems within HVAC units is recognized as an effective method for bioaerosol elimination, the design and optimization of these in-duct UVGI systems need further exploration. Task 1. Inactivation of Deposited Bioaerosols on Food Contact Surfaces with UV-C LED Devices. The airborne transmission of infectious diseases and bioaerosol-induced cross-contamination pose significant challenges in the food, dairy, and pharma industries. It is crucial to study and understand bioaerosols for both environmental and human well-being concerning public health and food safety. This study evaluated the effectiveness of 279 nm UV-C LED irradiation for decontaminating bioaerosols, specifically containing microorganisms like E. coli (C3040 - kanamycin-resistant strain), Salmonella Enteritis (ATCC 4931), and Pseudomonas fragi (ATCC 4973), on food contact surfaces. Borosilicate glass, silicon rubber, and stainless steel (316L) surfaces were selected for experimentation for their dominance in the food industry. A 50µL cell suspension was aerosolized at 25 psi pressure using a 4-jet BLAM Nebulizer within a customized glass chamber and then deposited onto surface coupons. The serial dilution approach was used for the microbial enumeration, followed by double plating and triple exposures. With a low RMSE and high R2 values, the biphasic kinetic model demonstrated the excellent goodness of fit parameters. At a UV-C dose of 6 mJ.cm-2, glass surfaces showed the maximum microbial inactivation ( i.e. 2.80, 3.81, and 3.56 log CFU/mL for E. coli, Salmonella, and P. fragi, respectively). Stainless steel and silicon rubber did not have any significant difference in microbial inactivation. Surprisingly, microbial inactivation increased with increasing UV-C exposure, although the rate of inactivation decreased significantly at higher doses. This task clearly indicates that UV-C LEDs have the ability to effectively disinfect bioaerosols on food contact surfaces. Task 2: Inactivation of Bioaerosols (in air) with UV-C LED Devices. This study aimed to investigate the effectiveness of UV-C LED devices ( 279 nm peak wavelength) on aerosolized bacterial inactivation. We designed and developed a UV-C disinfection system for bioaerosol treatment. The chamber's shape, size, and internal structure was engineered to ensure that all bioaerosols get adequate UV-C exposure. A nebulizer and an impinger were connected to the system at the inlet and outlet of the system. A forced air system was also connected to ensure that all bioaerosols pass through the UV-C exposure zone. Preliminary experiments were conducted using Escherichia coli (ATCC 25922) as bioaerosol. Bioaerosols were generated in a Blaustein Atomizing Module nebulizer (BLAM) at 20 psi and passed through the UV-C chamber at a flow rate ranging from 1 meter per second. The bioaerosols were collected in a liquid impinger, after which samples were taken for serial dilution and analyzed using classical platting technique on TSA plates. 1 to 0.5 log10 reduction of Escherichia coli aerosols were observed in preliminary trials. We observed that LED devices were delivering the lower dosage as expected. The log reduction achieved was significantly lower. The UV-C intensity was several orders of magnitude lower as measured by a spectrometer. From these results and initial testing, we designed a different treatment device which uses a 255 nm LED and exhibits high intensity ( >2.5) and high dose (> 8 mJ/cm2). The reactor treatment chamber (Quartz cylindrical shape with 150 cm^3 size, and circumferential 254 nm LED located at the outside perimeter to ensure that all bioaerosols get adequate UV-C exposure. A nebulizer and an impinger were connected to the system at the inlet and outlet of the system. A forced air system was also connected to ensure that all bioaerosols pass through the UV-C exposure zone. A new series of tests were completed using the updated system. We hypothesized that the enhanced log reduction should be achieved as the exposure dose will increase significantly. In summary, UV rate constant 'k (2.3026/D10),' is a species-dependent property in microorganisms, linking their inactivation efficiency to the UV-C dose. As we were concerned about delivered dose in the system due to low residence time and LED fluence. A second set of LEDs was added to the set up and characterization was conducted to determine the fluence rate delivered to the microorganisms during our test. Enterica, serovar Typhimurium ATCC 700720 was selected due to relatively high D10 (4.3 mJ/cm2). As the dosage was increased by a factor of 1.9 approximately, an increase in log inactivation by factor of 2.2 was observed. We anticipate variability in the UV rate constants across different bacteria, viruses, and fungi. Notably, airborne microbes are generally more susceptible to UV irradiation compared to the same microbes in liquid suspensions or on surfaces. This increased susceptibility is attributed to several factors. These include the effects of water absorption, the contrast in air and water viscosity--which leads to more turbulence and diffusion in air--and the physical stress imposed on microbes through aerosolization. The sensitivity of airborne microbes to UV is much greater than that of microbes in suspensions or in films on the surface of agar plates. Bacteria are about five times more resistant in water than in air at low humidity while viruses are three times more resistant. However, these ratios can differ substantially among different microbial species. The scientific explanation that microbes are more susceptible in air than in water may involve several key factors. Water absorbs UV but water-based rate constant studies generally account for the absorptivity of water. There is considerably more turbulence and diffusion in air than in water due to the much lower friction and this would cause tumbling and more mixing, which would ensure that airborne populations are more evenly exposed. In addition, aerosolization may reduce microbial survival potential through physical damage. This hypothesis will be tested in the next reporting period.
Publications
- Type:
Journal Articles
Status:
Awaiting Publication
Year Published:
2024
Citation:
Sharma, A., Singh, A., Pendyala, B., Balamurugan, S., Patras, A. (2004) Inactivation of Deposited Bioaerosols on Food Contact Surfaces with UV-C Light Emitting Diode Devices. Research Square (Preprint) https://doi.org/10.21203/rs.3.rs-3925783/v1
- Type:
Journal Articles
Status:
Accepted
Year Published:
2024
Citation:
Corson, E., Pendyala, B., Patras, A., DSouza D.H (2024). Inactivation of hepatitis A virus, feline calicivirus, and Tulane virus on Formica coupons using ultraviolet light technologies. Heliyon 10, e25201
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2024
Citation:
Mahmoud, H., Sharma, A., Patras, A.(2024). Aerosol disinfection by UV-C Light Emitting Diode Devices. 2024 IUVA AMERICAS CONFERENCE, May 20-22, Orlando Florida, USA
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2024
Citation:
Sharma, A., Singh, Pendyala, B., Patras, A.(2024)UV-C LED Assisted Bioaerosols Inactivation on Food Contact Surfaces. (2024) IUVA AMERICAS CONFERENCE, May 20-22, Orlando Florida, USA
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Progress 02/01/22 to 01/31/23
Outputs
Target Audience:Target audiences reached by this project includes UV systemsmanufacturers and designers (Trojan technologies, Aquafine Corporation, Sarin energy), regulatory agencies (FDA, USDA), food companies (Unique Food solutions, Vita Coco etc.), faculty (research, extension) and graduate students. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The Post-doctoral fellow was enrolled in a grant writing workshop at TSU, sponsered programs office. The workshop was for a duration of 2 weeks. The graduate students have been enrolled in aIdeator program at Vanderbilt University where they will learn to pitch ideas to investors. This is a great apporunity for the students. In addition, the students will enroll in NSF ICORP program in fall to develop business skills.The principal aim of the Mid-South Hub is to cultivate the generation of deep technology ventures that arise from the research and invention activities at regionally localized institutions of higher education (IHEs) and US National Laboratories. The programmatic purpose of the Mid-South Hub is to develop best practices as a scholarly incubator that informs future NSF programmatic investments using data driven approaches. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?The team will continue to optimize the UV systems and aimto develop microbial kinetic curves for selected microbes. We will conduct a series of test using the aerolization UV system including computational fluid dynamics. The team will enage with UV system manufacturers and will showcase the findings. The team will also present scientific findings at National and Internationa confereces. The team is also in touch with Tech Transfer team at TSU to creat IP/patent.
Impacts
What was accomplished under these goals?
A thorough lierature review was conducted on aerosols and aerosols deposited on surfaces. Grand challenges in aerosol disinfection were identified in a knowledge transfer session at Tennessee State University in fall of 2022. Based on knowledge gaps, an experimental plan waswas devised. A Master student and a post-doctoral fellow were alsorecruited in the project in fall of 2022. Microbiological cross-contamination has been a contributing factor to several well-documented outbreaks of foodborne illness. In practice, infected droplets with multiple microorganisms can land on food contact surfaces and form biofilms. Biofilms can harbor pathogens and spoilage microorganisms that can lead to food contamination and spoilage if not sanitized or disinfected.In this reporting period (2022-2023), twodifferent case studies were conducted. The team designed andconstructed a surface and air disinfection system. Both systems are beingtested against a suite of microbes. In the first case study,we investigated the effectiveness of ultraviolet light (UV-C) emitting diodes for the decontamination of stainless steel food contact surfaces. Listeria monocytogenes (ATCC 19115), Escherichia coli (ATCC 25922), and Salmonella enterica serovar Typhimurium (ATCC 700720) were chosen as challenge microorganisms. Target microorganisms were subjected to UV-C dosages of 0, 2, 4, 6, and 8 mJ cm−2 at an average fluence of 0.163 mW/cm2 using a near-collimated beam operating at 279 nm wavelength. Escherichia coli showed lower sensitivity to UV-C light compared to Salmonella Typhimurium and followed first-order kinetics. Escherichia coli and Salmonella Typhimurium were reduced by more than 3-log10 cycles at the maximum UV dosage of 12 mJ cm−2. In contrast, Listeria monocytogenes followed the Weibull model with an apparent shoulder in the initial doses. A maximum reduction of 4.4-log10 was achieved at the highest exposure level. This study showed that UV-C LED devices represent an excellent alternative for the inactivation of foodborne microorganisms in droplets. Results clearly demonstrate that UV-C LED devices can serve as an additional sanitation method to routine cleaning practices, which are commonly utilized in the food industry. The aforementioned findings are critical in understanding the inactivation of microorganisms in a thin-film droplet. We hypothesize that diffuse reflectivity spreads photons in all directions, regardless of the incident angle of incoming light rays. Perhaps the back reflection from the stainless steel coupon may explain the lower D value of target microorganisms compared to microbes suspended in clear solutions under stirred conditions. In addition, photons at 279 nm may cause protein damage and form dimers. The usefulness of surface rate constants is critical for equipment sterilization and disinfection of food contact surfaces. The inactivation rates of microbes on surfaces may vary depending on the type of surface used for the studies. Perhaps it is worth noting that the UV-C sensitivity of microorganisms on surfaces may be higher or lower than observed in water, for any given species; the absolute differences do not seem great that it would invalidate the use of water-based rate constants to predict surface disinfection rates. In the second case study, we tested the aerolization system and aerolized Salmonella enterica serovar Typhimurium (ATCC 700720) in a buffer system at a air flow-rate of 1.2 l/sec at 80% humidity, at air pressure of 50 psi. The recovery ofsalmonellain the impinger(sampler) was very low. The team is modifying the system to increase the recovery. We anticipate this modificationto be completed in 2 weeks (mid June, 2023).
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Sharma, A., M, Housyn., Brahmaiah., P., Sampathkumar., B., Patras, A. (2023). UV-C inactivation of microorganisms in droplets on food contact surfaces using UV-C light-emitting diode devices. Frontiers in Food Science and Technology, Volume 3, doi.org/10.3389/frfst.2023.1182765
- Type:
Conference Papers and Presentations
Status:
Submitted
Year Published:
2023
Citation:
Sharma, A., M, Housyn., Pendyala, B., Patras, A. (2023). Microbial Disinfection of Food-Contact Surfaces Using a Germicidal Short-Wave Ultraviolet Light (279 nm) Emitting Diode System, IAFP 15-19 July, Toronto
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