Bahram Zargar - Academia.edu (original) (raw)

Papers by Bahram Zargar

for serving as my committee members and helping me throughout this project. I also want to thank ... more for serving as my committee members and helping me throughout this project. I also want to thank Dr. Neil Forbes for accepting to be the external examiner of my thesis despite of his tight schedule. I would especially like to thank Dr. Perry Chou and Dr. Syed Ali Sattar who generously supported me in using their facilities and lab to fulfill this project. Thanks to all my colleagues and the staff at the chemical engineering department of University of Waterloo and at BMI department of University of Ottawa. A special thanks to my family. Words cannot express how grateful I am to my mother and father, for all of the sacrifices that you have made. I would also like to thank all of my friends who supported me throughout my study, and encouraged me towards my goal. v

PubMed, Feb 16, 2023

We report here a carrier platform (Teflon; 30.0 × 60.0 × 0.9 cm) and a carrier retrieval device t... more We report here a carrier platform (Teflon; 30.0 × 60.0 × 0.9 cm) and a carrier retrieval device to assess pathogen decontamination of high-touch environmental surfaces (HITES) by wiping. Each one of the nine metallic disks (1 cm diameter and 0.7 mm thick) received 10 μL of the microbial suspension in a soil load, the inocula dried and the platform then wiped with a piece of fabric presoaked in a control or disinfectant fluid; the used wipe was immediately applied on a second platform with sterile disks to assess microbial transfer. Each test and control disk from a given platform was separately and simultaneously retrieved into 10 mL of an eluent/neutralizer for assays at the end of the contact time (total of 5 min, starting from the beginning of the wiping). Staphylococcus aureus and Acinetobacter baumannii were used as representative HITES-borne pathogens. The wipes tested separately contained 0.26% of a quaternary ammonium compound (Product A), and 250 ppm sodium hypochlorite at neutral pH (Product B). The control fabric (Product C) was dampened with a buffer containing a detergent. Product A achieved a >4 log10 (>99.99%) reduction in the viability of the bacteria on wiping with a barely detectable level of transfer of CFUs to clean disks. Product B achieved a >2 log10 (>99.00%) reduction in the viability of the test microbes while transferring a higher level of CFUs as compared to Product A. With Product C, there was a <1 log10 (<86.2%) reduction in the viability of the test microbes while transferring >1% of the contamination.

bioRxiv (Cold Spring Harbor Laboratory), May 20, 2022

Clostridium is a genus of Gram-positive obligate anaerobic bacteria. Some species of Clostridium,... more Clostridium is a genus of Gram-positive obligate anaerobic bacteria. Some species of Clostridium, including C. sporogenes, may be of use in bacteria-mediated cancer therapy. Spores of Clostridium are inert in healthy normoxic tissue, but germinate when in the hypoxic regions of solid tumors, causing tumor regression. However, such treatments fail to completely eradicate tumors because of higher oxygen levels rise at the tumor's outer rim. In this study, we demonstrate that a degree of aerotolerance can be introduced to C. sporogenes by transfer of the noxA gene from C. aminovalericum. NoxA is a water-forming NADH oxidase enzyme. Thus, its activity has no detrimental effect on cell viability. In addition to its potential in cancer treatment, the noxA-expressing strain described here could be used to alleviate challenges related to oxygen sensitivity of C. sporogenes in biomanufacturing. .

John Wiley & Sons, Inc. eBooks, Oct 16, 2012

Most cancer chemotherapies cause severe side effects due mainly to the toxicity of the drugs to n... more Most cancer chemotherapies cause severe side effects due mainly to the toxicity of the drugs to normal healthy cells. Conventional drugs lack satisfactory specifi city towards cancer cells, and have diffi culties overcoming biological barriers; this highlights the importance of developing safe and effective delivery systems. Opportunities for the design of intelligent drug delivery vehicles are provided by the unique physiological properties of tumor tissues and the overexpression of specifi c receptors in tumor cells and neovasculature. These delivery vehicles include peptides, polymers and lipids. Targeting ligands, such as cell targeting peptides, have been used to decorate delivery vehicles in order to guide the therapeutic or diagnostic agents to tumor sites and enhance their effi cacy. Recently, attention has been drawn to bacteria-mediated cancer therapy. This approach targets the tumor environment by taking advantage of the wide fl exibility of bacterial genetics. This chapter focuses on recent progress in drug delivery approaches in cancer therapy.

Journal of Applied Microbiology, Aug 28, 2021

The air indoors has profound health implications as it can expose us to pathogens, allergens and ... more The air indoors has profound health implications as it can expose us to pathogens, allergens and particulates either directly or via contaminated surfaces. There is, therefore, an upsurge in marketing of air decontamination technologies, but with no proper validation of their claims. We addressed the gap through the construction and use of a versatile room‐sized (25 m3) chamber to study airborne pathogen survival and inactivation.

Canadian Journal of Microbiology, Nov 1, 2019

Environmentally stable and disinfectant-resistant oocysts of Cryptosporidium spp. shed in the fec... more Environmentally stable and disinfectant-resistant oocysts of Cryptosporidium spp. shed in the feces of infected humans and animals frequently contaminate water resources and are subsequently spread via potable and recreational waters. The current monoclonal-antibody-based methods for detecting them in water are slow, labor-intensive, and demand skills to interpret the results. We have developed DNA-aptamer-based aptasensors, coupled with magnetic beads, to detect and identify the oocysts of C. parvum for monitoring recreational and drinking water sources. A sensitive and specific electrochemical aptasensor (3′-biotinylated R4–6 aptamer) was used as a secondary ligand to bind the streptavidin-coated magnetic beads. This was incorporated into a probe using gold nanoparticle modified screen-printed carbon electrodes. Square wave voltammetry allowed for specific recognition of C. parvum oocysts. The aptamer-coated probes had an oocyst detection limit of 50. It did not bind to the cysts of Giardia duodenalis, another common waterborne pathogen, thus indicating its high specificity for the target pathogen. The system could successfully detect C. parvum oocysts in spiked samples of the raw lake and river waters. Therefore, the combined use of the aptasensor and magnetic beads has the potential to monitor water quality for C. parvum oocysts in field samples without relying on monoclonal antibodies and skill-demanding microscopy.

Journal of Environmental and Public Health, 2016

The world total of passenger cars is expected to go from the current one billion to >2.5 billion ... more The world total of passenger cars is expected to go from the current one billion to >2.5 billion by 2050. Cars for domestic use account for ∼74% of the world's yearly production of motorized vehicles. In North America, ∼80% of the commuters use their own car with another 5.6% travelling as passengers. With the current life-expectancy of 78.6 years, the average North American spends 4.3 years driving a car! This equates to driving 101 minutes/day with a lifetime driving distance of nearly 1.3 million km inside the confined and often shared space of the car with exposure to a mix of potentially harmful pathogens, allergens, endotoxins, particulates, and volatile organics. Such risks may increase in proportion to the unprecedented upsurge in the numbers of family cars globally. Though new technologies may reduce the levels of air pollution from car exhausts and other sources, they are unlikely to impact our in-car exposure to pathogens. Can commercial in-car air decontamination devices reduce the risk from airborne infections and other pollutants? We lack scientifically rigorous protocols to verify the claims of such devices. Here we discuss the essentials of a customized aerobiology facility and test protocols to assess such devices under field-relevant conditions.

Air Quality, Atmosphere & Health, Dec 28, 2019

This study developed a computational fluid dynamics (CFD) model to assess the impact of the site ... more This study developed a computational fluid dynamics (CFD) model to assess the impact of the site of location of a commercial device (HEPA filter/ultraviolet light) on its capacity for microbial decontamination of indoor air. The three locations of the air decontamination device (ADD) in the aerobiology chamber were at the center, the middle of one of the lateral sides, and at the middle of the side in front of the axial air circulating fan. The findings were then compared to the experimental data generated in an earlier study on the same device using aerosolized Staphylococcus aureus as the challenge. The findings of the CFD model were strongly correlated to the experimental results, and the best site for the ADD was found to be at the middle of one of the lateral sides of the chamber. In this state, the microbial decontamination efficiency of the ADD was 99.46%. Additionally, this modeling study identified (a) the device’s optimal location in the chamber for microbial decontamination and the device’s effectiveness, (b) the axial fan’s location and its ability to uniformly distribute the airborne bacteria inside the chamber, and (c) suitability of the air samples collecting from the chamber’s center. The incorporation of this model could boost the design and construction of the chamber, reduce the need for laboratory experimentation, and also help to simulate and investigate an ADD’s efficacy for maximum reduction of airborne pathogens.

Letters in Applied Microbiology, Mar 1, 2019

Significance and Impact of the Study: The innovative and generic test protocol described can quan... more Significance and Impact of the Study: The innovative and generic test protocol described can quantitatively assess the reduction in environmental surface contamination from microbial decontamination of indoor air in the same setting. This added advantage from air decontamination has implications for infection prevention and control in healthcare and other settings without the need for additional expense or effort. Continuous operation of an air decontamination device, such as the one tested here, can lead to ongoing reductions in pathogens in air and on environmental surfaces.

Clostridium is a genus of Gram-positive obligate anaerobic bacteria. Some species of Clostridium,... more Clostridium is a genus of Gram-positive obligate anaerobic bacteria. Some species of Clostridium, including C. sporogenes, may be of use in bacteria-mediated cancer therapy. Spores of Clostridium are inert in healthy normoxic tissue, but germinate when in the hypoxic regions of solid tumors, causing tumor regression. However, such treatments fail to completely eradicate tumors because of higher oxygen levels rise at the tumor’s outer rim. In this study, we demonstrate that a degree of aerotolerance can be introduced to C. sporogenes by transfer of the noxA gene from C. aminovalericum. NoxA is a water-forming NADH oxidase enzyme. Thus, its activity has no detrimental effect on cell viability. In addition to its potential in cancer treatment, the noxA-expressing strain described here could be used to alleviate challenges related to oxygen sensitivity of C. sporogenes in biomanufacturing.

Le Doyen de la Facuite des itudes supdrieures et postdodoraies I Dean of the Faculty of Graduate ... more Le Doyen de la Facuite des itudes supdrieures et postdodoraies I Dean of the Faculty of Graduate and Postdoctorai Studies R eproduced with perm ission of the copyright owner. Further reproduction prohibited without permission. i * i Canada R eproduced with perm ission of the copyright owner. Further reproduction prohibited without permission.

Letters in Applied Microbiology, Dec 28, 2022

for serving as my committee members and helping me throughout this project. I also want to thank ... more for serving as my committee members and helping me throughout this project. I also want to thank Dr. Neil Forbes for accepting to be the external examiner of my thesis despite of his tight schedule. I would especially like to thank Dr. Perry Chou and Dr. Syed Ali Sattar who generously supported me in using their facilities and lab to fulfill this project. Thanks to all my colleagues and the staff at the chemical engineering department of University of Waterloo and at BMI department of University of Ottawa. A special thanks to my family. Words cannot express how grateful I am to my mother and father, for all of the sacrifices that you have made. I would also like to thank all of my friends who supported me throughout my study, and encouraged me towards my goal. v

Journal of Applied Microbiology, 2021

Abstract Aim The air indoors has profound health implications as it can expose us to pathogens, a... more Abstract Aim The air indoors has profound health implications as it can expose us to pathogens, allergens and particulates either directly or via contaminated surfaces. There is, therefore, an upsurge in marketing of air decontamination technologies, but with no proper validation of their claims. We addressed the gap through the construction and use of a versatile room‐sized (25 m3) chamber to study airborne pathogen survival and inactivation. Methods and Results Here, we report on the quantitative recovery and detection of an enveloped (Phi6) and a non‐enveloped bacteriophage (MS2). The two phages, respectively, acted as surrogates for airborne human pathogenic enveloped (e.g., influenza, Ebola and coronavirus SARS‐CoV‐2) and non‐enveloped (e.g., norovirus) viruses from indoor air deposited directly on the lawns of their respective host bacteria using a programmable slit‐to‐agar air sampler. Using this technique, two different devices based on HEPA filtration and UV light were tested for their ability to decontaminate indoor air. This safe, relatively simple and inexpensive procedure augments the use of phages as surrogates for the study of airborne human and animal pathogenic viruses. Conclusions This simple, safe and relatively inexpensive method of direct recovery and quantitative detection of viable airborne phage particles can greatly enhance their applicattion as surrogates for the study of vertebrate virus survival in indoor air and assessment of technologies for their decontamination. Significance and Impact of the Study The safe, economical and simple technique reported here can be applied widely to investigate the role of indoor air for virus survival and transmission and also to assess the potential of air decontaminating technologies.

Sustainability, 2021

Transmission and spread of exhaled contaminants in the air may cause many airborne infectious dis... more Transmission and spread of exhaled contaminants in the air may cause many airborne infectious diseases. In addition to appropriate ventilation, air cleaner devices are used as one of the most common ways to improve the indoor air quality. Therefore, it is necessary to understand the performance of an air cleaner under different operating conditions. This study mainly concerns investigating the effect of presence or absence of furniture and its displacement on the removal rate of the particles leaving a person’s mouth while coughing in an isolated room. Moreover, the effect of air exit angle of the device on removal rate of contaminated particles and the pattern of their dispersion within a room was studied. To this aim, computational fluid dynamics were employed to examine the mentioned effects by using the Eulerian− Lagrangian method. As the results indicated, when the furniture was placed farther away from the device, more particles were removed by the device. Additionally, the ai...

Air Quality, Atmosphere & Health, 2019

This study developed a computational fluid dynamics (CFD) model to assess the impact of the site ... more This study developed a computational fluid dynamics (CFD) model to assess the impact of the site of location of a commercial device (HEPA filter/ultraviolet light) on its capacity for microbial decontamination of indoor air. The three locations of the air decontamination device (ADD) in the aerobiology chamber were at the center, the middle of one of the lateral sides, and at the middle of the side in front of the axial air circulating fan. The findings were then compared to the experimental data generated in an earlier study on the same device using aerosolized Staphylococcus aureus as the challenge. The findings of the CFD model were strongly correlated to the experimental results, and the best site for the ADD was found to be at the middle of one of the lateral sides of the chamber. In this state, the microbial decontamination efficiency of the ADD was 99.46%. Additionally, this modeling study identified (a) the device’s optimal location in the chamber for microbial decontamination and the device’s effectiveness, (b) the axial fan’s location and its ability to uniformly distribute the airborne bacteria inside the chamber, and (c) suitability of the air samples collecting from the chamber’s center. The incorporation of this model could boost the design and construction of the chamber, reduce the need for laboratory experimentation, and also help to simulate and investigate an ADD’s efficacy for maximum reduction of airborne pathogens.

Canadian Journal of Microbiology, 2019

Environmentally stable and disinfectant-resistant oocysts of Cryptosporidium spp. shed in the fec... more Environmentally stable and disinfectant-resistant oocysts of Cryptosporidium spp. shed in the feces of infected humans and animals frequently contaminate water resources and are subsequently spread via potable and recreational waters. The current monoclonal-antibody-based methods for detecting them in water are slow, labor-intensive, and demand skills to interpret the results. We have developed DNA-aptamer-based aptasensors, coupled with magnetic beads, to detect and identify the oocysts of C. parvum for monitoring recreational and drinking water sources. A sensitive and specific electrochemical aptasensor (3′-biotinylated R4–6 aptamer) was used as a secondary ligand to bind the streptavidin-coated magnetic beads. This was incorporated into a probe using gold nanoparticle modified screen-printed carbon electrodes. Square wave voltammetry allowed for specific recognition of C. parvum oocysts. The aptamer-coated probes had an oocyst detection limit of 50. It did not bind to the cysts ...

Letters in Applied Microbiology, 2018

Applied and environmental microbiology, May 15, 2017

Family cars represent ∼74% of the yearly global output of motorized vehicles. With a life expecta... more Family cars represent ∼74% of the yearly global output of motorized vehicles. With a life expectancy of ∼8 decades in many countries, the average person spends >100 min daily inside the confined and often shared space of the car, with exposure to a mix of potentially harmful microbes. Can commercial in-car microbial air decontamination devices mitigate the risk? Three such devices (designated devices 1 to 3) with HEPA filters were tested in the modified passenger cabin (3.25 m(3)) of a four-door sedan housed within a biosafety level 3 containment facility. Staphylococcus aureus (ATCC 6538) was suspended in a soil load to simulate the presence of body fluids and aerosolized into the car's cabin with a 6-jet Collison nebulizer. A muffin fan (80 mm by 80 mm, with an output of 0.17 m(3)/min) circulated the air inside. Plates (150 mm diameter) of Trypticase soy agar (TSA), placed inside a programmable slit-to-agar sampler, were held at 36 ± 1°C for 18 to 24 h and examined for CFU....

Journal of environmental and public health, 2016

The world total of passenger cars is expected to go from the current one billion to >2.5 billi... more The world total of passenger cars is expected to go from the current one billion to >2.5 billion by 2050. Cars for domestic use account for ~74% of the world's yearly production of motorized vehicles. In North America, ~80% of the commuters use their own car with another 5.6% travelling as passengers. With the current life-expectancy of 78.6 years, the average North American spends 4.3 years driving a car! This equates to driving 101 minutes/day with a lifetime driving distance of nearly 1.3 million km inside the confined and often shared space of the car with exposure to a mix of potentially harmful pathogens, allergens, endotoxins, particulates, and volatile organics. Such risks may increase in proportion to the unprecedented upsurge in the numbers of family cars globally. Though new technologies may reduce the levels of air pollution from car exhausts and other sources, they are unlikely to impact our in-car exposure to pathogens. Can commercial in-car air decontamination ...

for serving as my committee members and helping me throughout this project. I also want to thank ... more for serving as my committee members and helping me throughout this project. I also want to thank Dr. Neil Forbes for accepting to be the external examiner of my thesis despite of his tight schedule. I would especially like to thank Dr. Perry Chou and Dr. Syed Ali Sattar who generously supported me in using their facilities and lab to fulfill this project. Thanks to all my colleagues and the staff at the chemical engineering department of University of Waterloo and at BMI department of University of Ottawa. A special thanks to my family. Words cannot express how grateful I am to my mother and father, for all of the sacrifices that you have made. I would also like to thank all of my friends who supported me throughout my study, and encouraged me towards my goal. v

PubMed, Feb 16, 2023

We report here a carrier platform (Teflon; 30.0 × 60.0 × 0.9 cm) and a carrier retrieval device t... more We report here a carrier platform (Teflon; 30.0 × 60.0 × 0.9 cm) and a carrier retrieval device to assess pathogen decontamination of high-touch environmental surfaces (HITES) by wiping. Each one of the nine metallic disks (1 cm diameter and 0.7 mm thick) received 10 μL of the microbial suspension in a soil load, the inocula dried and the platform then wiped with a piece of fabric presoaked in a control or disinfectant fluid; the used wipe was immediately applied on a second platform with sterile disks to assess microbial transfer. Each test and control disk from a given platform was separately and simultaneously retrieved into 10 mL of an eluent/neutralizer for assays at the end of the contact time (total of 5 min, starting from the beginning of the wiping). Staphylococcus aureus and Acinetobacter baumannii were used as representative HITES-borne pathogens. The wipes tested separately contained 0.26% of a quaternary ammonium compound (Product A), and 250 ppm sodium hypochlorite at neutral pH (Product B). The control fabric (Product C) was dampened with a buffer containing a detergent. Product A achieved a >4 log10 (>99.99%) reduction in the viability of the bacteria on wiping with a barely detectable level of transfer of CFUs to clean disks. Product B achieved a >2 log10 (>99.00%) reduction in the viability of the test microbes while transferring a higher level of CFUs as compared to Product A. With Product C, there was a <1 log10 (<86.2%) reduction in the viability of the test microbes while transferring >1% of the contamination.

bioRxiv (Cold Spring Harbor Laboratory), May 20, 2022

Clostridium is a genus of Gram-positive obligate anaerobic bacteria. Some species of Clostridium,... more Clostridium is a genus of Gram-positive obligate anaerobic bacteria. Some species of Clostridium, including C. sporogenes, may be of use in bacteria-mediated cancer therapy. Spores of Clostridium are inert in healthy normoxic tissue, but germinate when in the hypoxic regions of solid tumors, causing tumor regression. However, such treatments fail to completely eradicate tumors because of higher oxygen levels rise at the tumor's outer rim. In this study, we demonstrate that a degree of aerotolerance can be introduced to C. sporogenes by transfer of the noxA gene from C. aminovalericum. NoxA is a water-forming NADH oxidase enzyme. Thus, its activity has no detrimental effect on cell viability. In addition to its potential in cancer treatment, the noxA-expressing strain described here could be used to alleviate challenges related to oxygen sensitivity of C. sporogenes in biomanufacturing. .

John Wiley & Sons, Inc. eBooks, Oct 16, 2012

Most cancer chemotherapies cause severe side effects due mainly to the toxicity of the drugs to n... more Most cancer chemotherapies cause severe side effects due mainly to the toxicity of the drugs to normal healthy cells. Conventional drugs lack satisfactory specifi city towards cancer cells, and have diffi culties overcoming biological barriers; this highlights the importance of developing safe and effective delivery systems. Opportunities for the design of intelligent drug delivery vehicles are provided by the unique physiological properties of tumor tissues and the overexpression of specifi c receptors in tumor cells and neovasculature. These delivery vehicles include peptides, polymers and lipids. Targeting ligands, such as cell targeting peptides, have been used to decorate delivery vehicles in order to guide the therapeutic or diagnostic agents to tumor sites and enhance their effi cacy. Recently, attention has been drawn to bacteria-mediated cancer therapy. This approach targets the tumor environment by taking advantage of the wide fl exibility of bacterial genetics. This chapter focuses on recent progress in drug delivery approaches in cancer therapy.

Journal of Applied Microbiology, Aug 28, 2021

The air indoors has profound health implications as it can expose us to pathogens, allergens and ... more The air indoors has profound health implications as it can expose us to pathogens, allergens and particulates either directly or via contaminated surfaces. There is, therefore, an upsurge in marketing of air decontamination technologies, but with no proper validation of their claims. We addressed the gap through the construction and use of a versatile room‐sized (25 m3) chamber to study airborne pathogen survival and inactivation.

Canadian Journal of Microbiology, Nov 1, 2019

Environmentally stable and disinfectant-resistant oocysts of Cryptosporidium spp. shed in the fec... more Environmentally stable and disinfectant-resistant oocysts of Cryptosporidium spp. shed in the feces of infected humans and animals frequently contaminate water resources and are subsequently spread via potable and recreational waters. The current monoclonal-antibody-based methods for detecting them in water are slow, labor-intensive, and demand skills to interpret the results. We have developed DNA-aptamer-based aptasensors, coupled with magnetic beads, to detect and identify the oocysts of C. parvum for monitoring recreational and drinking water sources. A sensitive and specific electrochemical aptasensor (3′-biotinylated R4–6 aptamer) was used as a secondary ligand to bind the streptavidin-coated magnetic beads. This was incorporated into a probe using gold nanoparticle modified screen-printed carbon electrodes. Square wave voltammetry allowed for specific recognition of C. parvum oocysts. The aptamer-coated probes had an oocyst detection limit of 50. It did not bind to the cysts of Giardia duodenalis, another common waterborne pathogen, thus indicating its high specificity for the target pathogen. The system could successfully detect C. parvum oocysts in spiked samples of the raw lake and river waters. Therefore, the combined use of the aptasensor and magnetic beads has the potential to monitor water quality for C. parvum oocysts in field samples without relying on monoclonal antibodies and skill-demanding microscopy.

Journal of Environmental and Public Health, 2016

The world total of passenger cars is expected to go from the current one billion to >2.5 billion ... more The world total of passenger cars is expected to go from the current one billion to >2.5 billion by 2050. Cars for domestic use account for ∼74% of the world's yearly production of motorized vehicles. In North America, ∼80% of the commuters use their own car with another 5.6% travelling as passengers. With the current life-expectancy of 78.6 years, the average North American spends 4.3 years driving a car! This equates to driving 101 minutes/day with a lifetime driving distance of nearly 1.3 million km inside the confined and often shared space of the car with exposure to a mix of potentially harmful pathogens, allergens, endotoxins, particulates, and volatile organics. Such risks may increase in proportion to the unprecedented upsurge in the numbers of family cars globally. Though new technologies may reduce the levels of air pollution from car exhausts and other sources, they are unlikely to impact our in-car exposure to pathogens. Can commercial in-car air decontamination devices reduce the risk from airborne infections and other pollutants? We lack scientifically rigorous protocols to verify the claims of such devices. Here we discuss the essentials of a customized aerobiology facility and test protocols to assess such devices under field-relevant conditions.

Air Quality, Atmosphere & Health, Dec 28, 2019

This study developed a computational fluid dynamics (CFD) model to assess the impact of the site ... more This study developed a computational fluid dynamics (CFD) model to assess the impact of the site of location of a commercial device (HEPA filter/ultraviolet light) on its capacity for microbial decontamination of indoor air. The three locations of the air decontamination device (ADD) in the aerobiology chamber were at the center, the middle of one of the lateral sides, and at the middle of the side in front of the axial air circulating fan. The findings were then compared to the experimental data generated in an earlier study on the same device using aerosolized Staphylococcus aureus as the challenge. The findings of the CFD model were strongly correlated to the experimental results, and the best site for the ADD was found to be at the middle of one of the lateral sides of the chamber. In this state, the microbial decontamination efficiency of the ADD was 99.46%. Additionally, this modeling study identified (a) the device’s optimal location in the chamber for microbial decontamination and the device’s effectiveness, (b) the axial fan’s location and its ability to uniformly distribute the airborne bacteria inside the chamber, and (c) suitability of the air samples collecting from the chamber’s center. The incorporation of this model could boost the design and construction of the chamber, reduce the need for laboratory experimentation, and also help to simulate and investigate an ADD’s efficacy for maximum reduction of airborne pathogens.

Letters in Applied Microbiology, Mar 1, 2019

Significance and Impact of the Study: The innovative and generic test protocol described can quan... more Significance and Impact of the Study: The innovative and generic test protocol described can quantitatively assess the reduction in environmental surface contamination from microbial decontamination of indoor air in the same setting. This added advantage from air decontamination has implications for infection prevention and control in healthcare and other settings without the need for additional expense or effort. Continuous operation of an air decontamination device, such as the one tested here, can lead to ongoing reductions in pathogens in air and on environmental surfaces.

Clostridium is a genus of Gram-positive obligate anaerobic bacteria. Some species of Clostridium,... more Clostridium is a genus of Gram-positive obligate anaerobic bacteria. Some species of Clostridium, including C. sporogenes, may be of use in bacteria-mediated cancer therapy. Spores of Clostridium are inert in healthy normoxic tissue, but germinate when in the hypoxic regions of solid tumors, causing tumor regression. However, such treatments fail to completely eradicate tumors because of higher oxygen levels rise at the tumor’s outer rim. In this study, we demonstrate that a degree of aerotolerance can be introduced to C. sporogenes by transfer of the noxA gene from C. aminovalericum. NoxA is a water-forming NADH oxidase enzyme. Thus, its activity has no detrimental effect on cell viability. In addition to its potential in cancer treatment, the noxA-expressing strain described here could be used to alleviate challenges related to oxygen sensitivity of C. sporogenes in biomanufacturing.

Le Doyen de la Facuite des itudes supdrieures et postdodoraies I Dean of the Faculty of Graduate ... more Le Doyen de la Facuite des itudes supdrieures et postdodoraies I Dean of the Faculty of Graduate and Postdoctorai Studies R eproduced with perm ission of the copyright owner. Further reproduction prohibited without permission. i * i Canada R eproduced with perm ission of the copyright owner. Further reproduction prohibited without permission.

Letters in Applied Microbiology, Dec 28, 2022

for serving as my committee members and helping me throughout this project. I also want to thank ... more for serving as my committee members and helping me throughout this project. I also want to thank Dr. Neil Forbes for accepting to be the external examiner of my thesis despite of his tight schedule. I would especially like to thank Dr. Perry Chou and Dr. Syed Ali Sattar who generously supported me in using their facilities and lab to fulfill this project. Thanks to all my colleagues and the staff at the chemical engineering department of University of Waterloo and at BMI department of University of Ottawa. A special thanks to my family. Words cannot express how grateful I am to my mother and father, for all of the sacrifices that you have made. I would also like to thank all of my friends who supported me throughout my study, and encouraged me towards my goal. v

Journal of Applied Microbiology, 2021

Abstract Aim The air indoors has profound health implications as it can expose us to pathogens, a... more Abstract Aim The air indoors has profound health implications as it can expose us to pathogens, allergens and particulates either directly or via contaminated surfaces. There is, therefore, an upsurge in marketing of air decontamination technologies, but with no proper validation of their claims. We addressed the gap through the construction and use of a versatile room‐sized (25 m3) chamber to study airborne pathogen survival and inactivation. Methods and Results Here, we report on the quantitative recovery and detection of an enveloped (Phi6) and a non‐enveloped bacteriophage (MS2). The two phages, respectively, acted as surrogates for airborne human pathogenic enveloped (e.g., influenza, Ebola and coronavirus SARS‐CoV‐2) and non‐enveloped (e.g., norovirus) viruses from indoor air deposited directly on the lawns of their respective host bacteria using a programmable slit‐to‐agar air sampler. Using this technique, two different devices based on HEPA filtration and UV light were tested for their ability to decontaminate indoor air. This safe, relatively simple and inexpensive procedure augments the use of phages as surrogates for the study of airborne human and animal pathogenic viruses. Conclusions This simple, safe and relatively inexpensive method of direct recovery and quantitative detection of viable airborne phage particles can greatly enhance their applicattion as surrogates for the study of vertebrate virus survival in indoor air and assessment of technologies for their decontamination. Significance and Impact of the Study The safe, economical and simple technique reported here can be applied widely to investigate the role of indoor air for virus survival and transmission and also to assess the potential of air decontaminating technologies.

Sustainability, 2021

Transmission and spread of exhaled contaminants in the air may cause many airborne infectious dis... more Transmission and spread of exhaled contaminants in the air may cause many airborne infectious diseases. In addition to appropriate ventilation, air cleaner devices are used as one of the most common ways to improve the indoor air quality. Therefore, it is necessary to understand the performance of an air cleaner under different operating conditions. This study mainly concerns investigating the effect of presence or absence of furniture and its displacement on the removal rate of the particles leaving a person’s mouth while coughing in an isolated room. Moreover, the effect of air exit angle of the device on removal rate of contaminated particles and the pattern of their dispersion within a room was studied. To this aim, computational fluid dynamics were employed to examine the mentioned effects by using the Eulerian− Lagrangian method. As the results indicated, when the furniture was placed farther away from the device, more particles were removed by the device. Additionally, the ai...

Air Quality, Atmosphere & Health, 2019

This study developed a computational fluid dynamics (CFD) model to assess the impact of the site ... more This study developed a computational fluid dynamics (CFD) model to assess the impact of the site of location of a commercial device (HEPA filter/ultraviolet light) on its capacity for microbial decontamination of indoor air. The three locations of the air decontamination device (ADD) in the aerobiology chamber were at the center, the middle of one of the lateral sides, and at the middle of the side in front of the axial air circulating fan. The findings were then compared to the experimental data generated in an earlier study on the same device using aerosolized Staphylococcus aureus as the challenge. The findings of the CFD model were strongly correlated to the experimental results, and the best site for the ADD was found to be at the middle of one of the lateral sides of the chamber. In this state, the microbial decontamination efficiency of the ADD was 99.46%. Additionally, this modeling study identified (a) the device’s optimal location in the chamber for microbial decontamination and the device’s effectiveness, (b) the axial fan’s location and its ability to uniformly distribute the airborne bacteria inside the chamber, and (c) suitability of the air samples collecting from the chamber’s center. The incorporation of this model could boost the design and construction of the chamber, reduce the need for laboratory experimentation, and also help to simulate and investigate an ADD’s efficacy for maximum reduction of airborne pathogens.

Canadian Journal of Microbiology, 2019

Environmentally stable and disinfectant-resistant oocysts of Cryptosporidium spp. shed in the fec... more Environmentally stable and disinfectant-resistant oocysts of Cryptosporidium spp. shed in the feces of infected humans and animals frequently contaminate water resources and are subsequently spread via potable and recreational waters. The current monoclonal-antibody-based methods for detecting them in water are slow, labor-intensive, and demand skills to interpret the results. We have developed DNA-aptamer-based aptasensors, coupled with magnetic beads, to detect and identify the oocysts of C. parvum for monitoring recreational and drinking water sources. A sensitive and specific electrochemical aptasensor (3′-biotinylated R4–6 aptamer) was used as a secondary ligand to bind the streptavidin-coated magnetic beads. This was incorporated into a probe using gold nanoparticle modified screen-printed carbon electrodes. Square wave voltammetry allowed for specific recognition of C. parvum oocysts. The aptamer-coated probes had an oocyst detection limit of 50. It did not bind to the cysts ...

Letters in Applied Microbiology, 2018

Applied and environmental microbiology, May 15, 2017

Family cars represent ∼74% of the yearly global output of motorized vehicles. With a life expecta... more Family cars represent ∼74% of the yearly global output of motorized vehicles. With a life expectancy of ∼8 decades in many countries, the average person spends >100 min daily inside the confined and often shared space of the car, with exposure to a mix of potentially harmful microbes. Can commercial in-car microbial air decontamination devices mitigate the risk? Three such devices (designated devices 1 to 3) with HEPA filters were tested in the modified passenger cabin (3.25 m(3)) of a four-door sedan housed within a biosafety level 3 containment facility. Staphylococcus aureus (ATCC 6538) was suspended in a soil load to simulate the presence of body fluids and aerosolized into the car's cabin with a 6-jet Collison nebulizer. A muffin fan (80 mm by 80 mm, with an output of 0.17 m(3)/min) circulated the air inside. Plates (150 mm diameter) of Trypticase soy agar (TSA), placed inside a programmable slit-to-agar sampler, were held at 36 ± 1°C for 18 to 24 h and examined for CFU....

Journal of environmental and public health, 2016

The world total of passenger cars is expected to go from the current one billion to >2.5 billi... more The world total of passenger cars is expected to go from the current one billion to >2.5 billion by 2050. Cars for domestic use account for ~74% of the world's yearly production of motorized vehicles. In North America, ~80% of the commuters use their own car with another 5.6% travelling as passengers. With the current life-expectancy of 78.6 years, the average North American spends 4.3 years driving a car! This equates to driving 101 minutes/day with a lifetime driving distance of nearly 1.3 million km inside the confined and often shared space of the car with exposure to a mix of potentially harmful pathogens, allergens, endotoxins, particulates, and volatile organics. Such risks may increase in proportion to the unprecedented upsurge in the numbers of family cars globally. Though new technologies may reduce the levels of air pollution from car exhausts and other sources, they are unlikely to impact our in-car exposure to pathogens. Can commercial in-car air decontamination ...