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Science Based Projects (SBP)

Science Based Projects (SBP)

 

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The COVID-19 pandemic has led to an increased need for constant sanitization and surfaces disinfection to avoid spreading of the virus to our surroundings. This has forced the scientific community to re-evaluate existing sanitization techniques. These include the use of antimicrobial sprays, wipes and hand sanitizers. While the general demand for these products has exponentially grown, there are no definitive answers about the best methods to achieve the desired level of disinfection. Both the Quaternary Ammonium Compounds (QACs) and hydrogen peroxide are recommended against SARS-CoV-2 by USEPA.

This study focuses on comparing the efficacy of commonly used antimicrobial wipes containing different active ingredients against some common pathogens.

The 4-fields-method was employed to determine the most effective antimicrobial wipe as it replicates the real-life practices.

The study confirmed that the QACs containing wipes such as Clorox and Lysol were more effective (99.9%) as per manufacturer’s claim. Surprisingly, PREEMPT wipes containing hydrogen peroxide and widely used in long-term cares were not effective and found to be lower than the control wipes (baby wipes). The study recommends using QACs wipes, while more research is needed to evaluate the efficacy against COVID.

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The purpose of this research was to assess the effectiveness of UV LED device designed by Violumas against common bacteria Escherichia coli (ATCC 25922), Coagulase Negative Staphylococcus (CONS, ATCC 12228) and MS2 RNA bacteriophage (ATCC 15591 B1) on porous and non-porous surfaces. As microorganisms are developing resistance against common chemical disinfectants and traditional mercury UV lamps are not ecofriendly, UV LED can be advantageous to kill the viruses and bacteria. Spread plate which is a very common, reliable and time efficient technique for enumeration of bacteria was used for E. coli whereas plaque assay was used for bacteriophage enumeration before and after UV treatment. Pathogen persistence on grocery packages is always a problem in food industry, so it was hypothesized that UV LED will be effective against selected microorganism. The results indicate that UV LED 265nm device is very effective in disinfection of bacteria and viruses. Present study proved that E. coli 25922 is more sensitive to UV LED 265nm as compared to MS2 RNA 15591-B1 as more than 99% reduction in number of counts was achieved in former case while 90% in latter. Because of great effectiveness of UV LED against studied microorganisms, it can be used in current scenario of COVID-19 to control the spread of virus by contacting touched surfaces, to sterile grocery items and to extend the shelf life of vegetables and fruits.

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Silani Cheese (SC) produces over 200 cheese products and the first company to produce Mozzarella and Ricotta in Canada. While expanding its business in the recent years, it focusses on the quality and compliance of the products. A recent investigation by their QC team had concerns for yeast and molds, which are common in the environment and a problem for dairy industries. Although infections arising from pathogenic yeasts, such as Candida albicans and Cryptococcus neoformans, are not transmitted through dairy products, allergic reactions due to some yeasts and molds are of concern. In addition, fermentative and spoilage activities of yeasts is of a growing concern, particularly limiting the shelf life. This capstone project was a collaboration between Centennial college and Silani Cheese, where Mozzarella cheese samples were investigated for the probiotic potential and potential pathogens. Food sampling was done in accordance with Compendium of Analytical Methods. Briefly, 25.0 g of sample was stomached with 225 mL of PBS and serially diluted. Lactic Acid Bacteria concentration was evaluated by plating 0.2 L on MRS agar and incubated at 35oC anaerobically for 72h. Probiotic potential was evaluated by the antimicrobial activity of the isolated LABs (from supernatant after centrifugation) against human pathogens. The yeast and mold concentrations were enumerated by spread plating (0.2 mL) on SDA agar at room temperature for 5 days, while total microbial counts were evaluated by plating on TSA. Enrichments were performed for specific food pathogens.

LAB concentration was found to be 106 cfu/g, and the supernatant inhibited E. coli with 10 mm clear zone. The yeast & mold concentration was found to be acceptable (< 1 cfu/g). Enrichment experiments were discontinued due to labs restrictions due to COVID closure.

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This capstone project was a collaboration between Centennial college and Silani Cheese, where Mozzarella cheese samples were investigated for the probiotic potential and potential pathogens. Food sampling was done in accordance with Compendium of Analytical Methods. Briefly, 25.0 g of sample was stomached with 225 mL of PBS and serially diluted. Lactic Acid Bacteria concentration was evaluated by plating 0.2 L on MRS agar and incubated at 35oC anaerobically for 72h. Probiotic potential was evaluated by the antimicrobial activity of the isolated LABs (from supernatant after centrifugation) against human pathogens. The yeast and mold concentrations were enumerated by spread plating (0.2 mL) on SDA agar at room temperature for 5 days, while total microbial counts were evaluated by plating on TSA. Enrichments were performed for specific food pathogens.

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LAB concentration was found to be 106 cfu/g, and the supernatant inhibited E. coli with 10 mm clear zone. The yeast & mold concentration was found to be acceptable (< 1 cfu/g). Enrichment experiments were discontinued due to labs restrictions due to COVID closure.

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The purpose of this study is focused on the comparison of antimicrobial effectiveness of three different solutions against streptococcal throat infections. As an alternative of antibiotic use, other over the counter pharmaceutical products are found in the market with a variety of properties and ingredients. This experiment is focused on the properties of three solutions, where the first is chemical-based (Betadine), the second is herbal-based (A. Vogel) and the third is based on Home-made remedies. The organisms used in this project are Streptococcus pyogenes and Streptococcus agalactiae as representatives of streptococcal throat infections. In addition, well diffusion method is used for the comparison of antimicrobial effectiveness based on the zone of inhibition developed by each product. According to the results of this experimental procedure, it is proved that S. pyogenes is more resistant than S. agalactiae as well as that higher concentration solutions present more antimicrobial effectiveness than diluted solutions. Finally, based on the comparison of the diameters of zones of inhibitions, it is proved that chemical-based solutions are not more effective than herbal-based solutions which disproves the third hypothesis stated in this study. Although, due to other limitation factors of this experiment, further investigations can be suggested for more reproducible data derived from multiple trials. .

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The significance of human breast milk for the wellbeing of infants and children have been thoroughly studied and well known for its nutritional value and antimicrobial and anti-inflammatory properties. In this study, the antimicrobial property of human breast milk against Staphylococcus aureus, Escherichia coli, and Streptococcus pyogenes, as compared with commercial formula milk, Similac ADVANCE step 1 by observing zones of inhibition and Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). In addition, the antimicrobial component containing a layer of human breast milk was determined, and the importance of human breast milk in the gut of the infant was highlighted. In conclusion, human breast milk inhibits the growth of Streptococcus pyogenes efficiently, and both human breast milk and formula milk relatively inhibit the growth of Escherichia coli. Furthermore, the skim layer of human breast milk contains a larger amount of the antibacterial component than the fat layer of human breast milk, and human breast milk exhibit the better inhibitory effect against bacteria than formula milk in gut environment mimic the condition.

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Growing food safety concerns mot specially in the fresh food items consumed is on the rise. Alternative ways of food disinfection are sought to improve safety of the masses. The experiment compared the efficiency of regular washing, citric acid treatment and UV LED treatments in the reduction and shelf life extension of cherry tomatoes and apple slices. Dilutions Untreated and treated tomatoes were plated into TSA plates at Day 0 and Day 7 intervals for the log reduction and inactivation. In accordance, untreated and treated tomatoes were kept for a period of 14 day to compare degradation and quality. Results suggested that regular washing is superior than UV in the reduction of microorganisms after treatment, while UV will have longer term effect in the control of microbial growth of organisms. UV treatment also inadvertently prolong shelf life by interfering enzymatic and microbial spoilage of tomatoes and apple slices.

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Water kefir has been used in many ways due to its probiotic effect which contains in its kefir grains live microorganisms capable of improving the intestinal microbial balance, producing beneficial effects to the individual’s health. Also, it is an alternative for the vegan and lactose intolerant population, since it is a non-dairy product. The main concern related to that product is the production of CO2 by yeast which leads to a decrease in the product's shelf-life. In this experiment biochemicals tests were performed to identify lactic acid bacteria and yeast from water kefir provided by Goodygut company. The realization of Gram stain and the analysis under microscope, it was possible to verify the morphology for both species, LAB as a rod-shaped gram-positive bacterium, and for yeast an egg-shaped morphology. The species identification was concluded using the Rapid ID and API 50 test. In addition, the temperature tolerance was used as a screening technique for yeast in order to verify if the temperature can directly impact on the growth of yeast cells. The result of this experiment suggests that when yeast cells are exposed to high temperatures, their growth is reduced. This result also proposes that further research will be needed for improvement of techniques aiming to increase the product’s shelf-life for the final consumer.

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Grocery plastic bags have been greatly used in grocery shopping, especially now that it is where most people spend their time. Besides the fact that it is handy and convenient, it is also a cheap retail for businesses. However, plastic bags are not environmentally friendly, and researchers have proven that it takes a thousand years for plastic bags to decompose in landfills. That is why eco bags were made; yet, most would say it is inconvenient to bring, gets contaminated easily, and too expensive. According to a study made by the Canadian plastic industry (2009), eco bags were tested for high levels of bacteria greater than those set for potable water. This research aimed to create bags with self-cleaning particles using nano silver. Recent studies have found that nano silver particles have antimicrobial properties, and when applied to objects it does not cause any adverse effects. This study opted to test the antimicrobial property of nano silver particles on fabric cloth, against Staphylococcus aureus and Salmonella cholerasuis. Two concentrations where used in this experiment 0.001 M and 0.003 M. Results of this study showed that nano particle was able to reduce the number of bacteria that was originally inoculated. Moreover, more than 90% were killed. Therefore, nano particle exhibited antimicrobial property.

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This experiment was focused on determining the microbial content in drinking water from the coolers in room 338 and room 428 of Centennial College, Morningside Campus by using the method of membrane filtration and also study the chemical parameter of hardness relative to tap water by the method of EDTA Titration. The media used for the microbial assay was TSA because one of the main objectives of the experiment was to determine the presence or absence of microbes in the water that is consumed by individuals. The other objective was to assess the hardness of drinking water relative to tap water. The hypotheses that were formed while looking at various research papers were that the microbial load was directly proportional to the volume of water filtered, and that tap water had more hardness (more Ca/Mg content) relative to drinking water. It was found that even at the same volume, there were differences in the microbial content of drinking water from both the coolers, and tap water had more Ca/Mg content than the drinking water. Therefore, it was concluded from this experiment that volume has no effect on the number of microbes present in water and tap water in Centennial College Bi-303 lab is not safe to drink.

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Ice-cream is a dairy product with good example and potential to act as a food matrix for delivering or as a carrier for probiotic bacteria. Fermented food products like probiotic yogurt is an excellent source for isolating probiotic microorganisms. Popularity and demand of probiotic yogurt has progressed reaching new markets due to its healthy image and desirable taste and texture profile. Using same technique, it is possible to produce probiotic ice cream. The aim of the study was to produce probiotic ice cream made from >106 cfu/g of isolated and characterized LAB strain, Bifidobacterium lactis from probiotic yogurt. The probiotic properties of isolated spp was determined by performing acid and bile resistant test for isolated culture which showed that it was able to grow in presence of 2% bile salts and pH 2. When compared to other food matrix like milk as vehicle, ice cream supports considerable viability and stability of probiotic cultures during production and storage.

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This study is conducted to compare the total number of mesophilic microorganisms present in the surfaces of raw produce retailed in supermarkets versus in open-air markets. The chosen enumeration method is the Total Plate Count Method and samples were collected using the swabbing technique. Results showed that for raw tomato samples, a higher number of mesophilic organisms are present in open-air market samples than the supermarket samples. For fresh apple samples, higher total plate counts were individually observed among the open-air market samples than the supermarket samples but comparing the mean values of each group signifies higher load in supermarket samples than open-air market samples. These comparative data can serve as basis for further investigative research and shows the significant effect of environmental exposure to microbial proliferation on fresh produce surfaces

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Since bamboo shoots are a traditional vegetable that is widely used in Asian cuisine, the demand for bamboo shoots in Canada is inevitable. In this project, the shelf lives of two pickled bamboo shoot products were evaluated. The goal of food preservation is to prevent the growth of spoilage bacteria, yeasts and moulds from spoiling food and extend the shelf life of the product. After the microbial evaluation of bamboo shoots in water and bamboo shoots in salted acidic brine for 4 weeks, there was no significant change in the population of microorganisms in the samples from the opening day until the end of the project. This might be the result of the sterilization step in the processing of these pickle bamboo shoots in manufacturer plants. To eliminate the effect of the sterilization step, dried bamboo shoots were tested and soaked in different aliquots (water and 10% NaCl solution) to test the effect of different environments on the shelf life of the product. However, the results showed that even dried bamboo shoots have not gone through any sterilization step, there was no change in the population of microorganisms in the samples during the project.

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SMicrobial contamination of street foods has a great contribution to the total Food borne epidemics reported across the globe. Though the Street vended foods are appreciated for its unique flavours and convenience, it also signifies the culture of a particular society. The present study aimed to assess the microbiological quality of street vended Chaats sold in different Chaat selling street restaurants in Greater Toronto Region (GTA). The total microbial content on these foods are fairly high due to unhygienic preparation and handling. In this project the samples (Chaat papri) are aseptically collected from three different Chaat vendors over a period of 3 weeks and tested for the presence of coliforms (Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae and Enterobacter aerogenes). Presence of different obligate bacterial pathogens were confirmed from the Chaat papri samples tested during the project.

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According to the Food and Agriculture Organization (FAO) approximately 33% of the world's land is degraded due to human activities associated with industrialization, urban densification, and agricultural intensification. These activities have resulted in the build-up of persistent toxic chemicals, compounds, salts, radioactive materials, or pathogens in soil, and ultimately causes harmful effects on teh environment and human health. Plants and animals are affected because polluted soils affect groundwater and surface water. Soil remediation is presently the most effective solution, it aims to reduce contamination levels significatnly below regulotroy toxic limit by removing the contaminants and/or immobalizing them and preventing their movement through subsuface geo-environment.

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Organophosphate pesticides are used in agricultural fields to kill insects that maytransfer pathogens between fields, and damage crops. Insects are killed when thepesticide enters their system through respiration or ingestion, and the neurotoxins willattack enzymes that control neurotransmitters from activating receptors in the muscle. Itis found that not only does this pesticide kill insects, it also negatively impacts humanhealth. When the system loses control of this activation process, the body will developvarious dangerous health issues that can lead to death. Humans can be exposed to thispesticide from consumption of food products that are grown on organophosphatepesticide sprayed fields, contracting Organophosphate poisoning.The application of this pesticide is now heavily regulated in Canada, and onlyused in critical situations. To safely manage the pesticides that are directly affectinghuman health, in-situ microbial bioremediation is implemented. A useful characteristic ofOrganophosphates is that the phosphate compound in the pesticide easily breaks downin the presence of water, making this pesticide biodegradable in the environment. Wecan use this to our advantage by creating a catalyzer that speeds up the degradationprocess using In-situ remediation. A specific probiotic organism that is able to degradeorganophosphates is Agrobacterium. When isolated using PCR, chemists are able toobtain a Phosphatase enzyme from the RNA which is able to break down phosphatecompounds. When mixed with water and injected in soil, this enzyme can effectivelycleave the organophosphates into non-toxic compounds that will safely degrade in theenvironment, successfully disposing of the toxic compounds.