Browsing by Author "Chamikara, H.J.M.P."

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Development of a mobile optical microscope at low cost
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Chamikara, H.J.M.P.
Optical microscope is an instrument, which uses visible light to magnify small objects that are not visible to our naked eyes. A typical light microscope used in our laboratories, can be very expensive and difficult to handle due to its weight. A maximum magnification limit of this instrument is ~1500X. An attempt is made to develop a small optical microscope that is very easy to handle with low production cost. The base of the microscope was made by an outer cover of a hard disk drive. Then a 15 cm long PVC pipe was attached to the base by gluing. A glass piece of 2cm × 2cm was placed on the top of the PVC pipe. It acts as the stage of the microscope. The prepared slide can be placed on this stage. A normal glass slide cannot be used here due to its size and thickness. Therefore, instead of the slide, a 2cm × 2cm size phone screen protector can be used. The specimen can be placed between the two layers of screen protector. Because screen protector consisted of the glass and a protecting film over that. Small earphone clip was used as the stage clips to hold the slide rigidly. The lense of a web camera was set to the top of the PVC tube above the glass stage. It was a 5 Mp camera lense with 30 mm radius of curvature. This lense act as the objective lense of the microscope. This lense gives nearly 40X-60X magnification. A white color bright Light-Emitting Diode (LED) was placed under the stage as the light source. It was powered by a 3.1 V phone battery. The intensity of LED can be controlled by using a volume controller. It can change the resistance (R) of the LED. Therefore, current (I) is changed. (V=IR) Thus intensity is controlled. So it acts as the condenser of a normal microscope. As there is no need of electricity power to this microscope, it can be easily used as a mobile instrument. The eyepiece was prepared by using a laser lense. It gives 10X magnification. The tube was attached to the PVC tube by using a spring. So it can be moved very easily. Focusing of the eye piece can be controlled by turning it around. It is the fine focus of this microscope. The movement of the objective lense around, acts as the coarse focus of this microscope. A total magnification of 400X- 500X could be achieved using this microscope. The total cost of production was around LKR 1500. This mobile instrument has potential to deliver better magnification with few improvements, without spending huge amount of money on other kinds of microscopes.
Isolation, Identification and Characterization of Microorganisms from Different Cosmetic Samples
(International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Chamikara, H.J.M.P.
Cosmetics means any substance or mixture of substances that are applied to the human body for use in cleaning, coloring, conditioning, improving, or altering the complexion, skin, hair, teeth, nails, lips or eyes. Cosmetics are generally mixtures of different chemical compounds derived from natural sources (such as coconut oil, king coconut oil, plant extracts and etc.) or may be synthetic or artificial. Cosmetics can be classified to 4 major groups depend on the area of the body intended for application including Oral care (Mouth wash, Toothpaste and etc.), Skin care (Lotions, Cream and etc.), Hair care (Shampoo, Hair cream and etc) and Perfumes. Microbial contamination of cosmetic products is a matter of great disadvantage to the industry and it can become a major cause of both consumer safety and economic loss. The moisture and nutrients present in cosmetics make them susceptible to microbial growth, however few cases of human injury due to contaminated cosmetics have been reported. For the manufacturer of cosmetic products, it is important to ensure that their products are free of pathogenic microorganisms and are safe for consumer use. Microorganisms in cosmetics may cause spoilage or chemical change in the product and can possibly harm health, beauty and personal care. The usages of cosmetics are increasing day by day, although it is contaminated by various microorganisms like Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida and etc. The purpose of this study was isolation and identification of microorganisms with the ability to survive and develop in cosmetics. Ten cosmetic samples from various brands which were used at home (Toothpaste, Cream, Lotion, Powder, Face wash, Hair oil, Hair cream, Shampoo, Body wash and body spray) were collected. The surface of sample container was disinfected with 70% Iso Propyl Alcohol before opening and removing contents. Then 10g of sample was dispersed in 90 ml sterile Eugon broth. From this 10-1 to 10-7 series of dilution were done and plated out on Tryptone Soy Agar to isolate and determine the bacterial load of the sample (Test Method – ISO 21149:2017). Sabouraud dextrose with chloramphenicol agar was used for the isolation and enumeration of yeasts and molds (Test method – ISO 16212:2017). Then plates were observed after 3 days incubation (25°C-yeast & molds, 32.5°C-bacteria). Morphological characterization of colonies was done by observing the appearance of colonies. Microscopic characterization was accomplished by Gram staining, motility test and endospore staining. Further biochemical tests and molecular biological tests were performed for further identification. Here, twenty-nine biochemical tests were carried out according to Cowan and steel’s manual. And molecular biological 16s rRNA sequencing was carried out for confirmation of identified strains from biochemical tests. The performed study confirms that microbiological contamination in cosmetic product is a current issue. According to the tests isolated strains were Pseudomonas aeruginosa from cream, lotion, Serratia marcescens from lotion, Aspergillus niger from powder and Escherichia coli from toothpaste. No micro contamination was observed from body wash, body spray, hair oil, shampoo, hair cream and facewash
Isolation, identification and characterization of phosphate solubilizing bacteria from rhizosphere soil of Aloe vera and Vigna unguiculata
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Chamikara, H.J.M.P.; Edirisinghe, E. A. A. D.
Phosphorus (P) is an essential element, which is next only to nitrogen, influencing plant growth and productivity. Unlike nitrogen, this element is not acquired through biochemical fixation, but comes from other sources to meet plant requirements. Phosphorus compounds in the soil can be categorized into three groups, including inorganic phosphate compounds, organic phosphate compounds of soil humus and organic/inorganic phosphate compounds associated with cells of living matter. Some of these are in insoluble form and some of them are in soluble form. Plants can absorb only the soluble part and soluble forms are infrequent than insoluble forms in soil. Phosphate Solubilizing Bacteria (PSB) can convert either insoluble organic phosphate or insoluble inorganic phosphate into soluble orthophosphates. They make phosphorus available for plants from insoluble organic and inorganic complex phosphorus sources by solubilization and mineralization. PSB were isolated from rhizosphere soil of Aloe vera and Vigna unguiculata, collected from Kuliyapitiya. Visual detection and even semi-quantitative estimation of the phosphate solubilization ability of microorganisms were carried out using serial dilution and spread plate method using Pikovskaya's Agar (PVK agar) medium. It showed clear zones around the microbial colonies in media containing insoluble mineral phosphates as the single P source. PVK agar plates were observed after incubating for 5 days and PSB strains were selected from the plates. Then selected strains were re-cultured in PVK agar medium. Then plates were observed after 5 days incubation and confirmed the PSB by clear zone formation. Morphological characterization of colonies was done by observing the appearance of colonies in PVK agar medium. Microscopic characterization was accomplished by Gram staining, motility test and endospore staining. Further biochemical tests and molecular biological tests were performed for further identification. Here, twenty-nine biochemical tests were carried out according to Cowan and Steel’s manual. And molecular biological 16S rRNA sequencing was carried out for the confirmation of identified strains from biochemical tests. According to the results obtained, isolated strains were identified as Pseudomonas aeruginosa, Achromobacter xylosoxidans from Aloe vera and Pseudomonas fluorescens, Bacillus subtilis from Vigna unguiculate.
Use of a water-boost rocket for the exposure plate method
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Chamikara, H.J.M.P.
The atmosphere of the earth is divided in to layers as troposphere, stratosphere, mesosphere and thermosphere. Each of these layers contain different types of airborne microorganisms owing to their physical and chemical characteristics such as types of gases, temperatures and atmospheric pressure. These microorganisms may have the ability to tolerate low O2 conditions, high temperature levels and survive even under UV rays. Therefore, isolation of these microorganisms can be useful in identifying the microbial diversity. Therefore, a ‘water-boost rocket’ method was developed to collect air samples from different layers of the atmosphere, where it can be used to isolate beneficial microorganisms from different layers of the atmosphere. The water-boost rocket consists of two main parts: the main rocket and the sample collecting part. Rocket is powered by water and compressed air. It is made out of a 1.5 L capacity plastic bottle. Four fins were attached to the bottom of the bottle using a plastic board. These fins help the rocket for its flight on a straight line. The nosecone of the rocket was made by using another 1.5 L plastic bottle. The neck and the bottom part of the bottle was removed to preserve the cone shaped part of the bottle. Then 50 g of clay was pasted on the top of the cone shaped part. This adds weight to the nose cone and the center of gravity is moved higher, thus making it more stable. The prepared nosecone was attached to the top of the rocket by gluing and taping. The nozzle of a size of 0.6 cm was prepared using a PVC pipe. The rocket launcher wad made up of wood. A separate pipe line was used to fill air to the rocket. Rocket can be filled with water through the nozzle. To launch the rocket, it has to be placed on the launcher and air should be pumped to the rocket by air pump or compressor. After pumping air, launcher can release the rocket. Normally this rocket flies up to 100 m of height. This height can be extended up to around 500m, if it is prepared with several stages by joining several bottles together. If we can use another type of gas instead of normal gas, it also can increase the height. The volume of water in the bottle and the pressure decides the maximum height that it can fly. A petri plate can be attached to the rocket using another nosecone, which can be attached over the pre-attached nosecone. Between two nosecones medium containing petri plate was placed. Then a timer circuit is placed on the first nosecone. This circuit helps to open and close the secondary nosecone at a specified time. When the nosecone is opened plate is exposed to the environment and then it should be closed within a pre-determined time period (3 sec.). After the rocket is landed, we can take the plate, incubate it and isolate the microorganisms. Different types of media can be used to isolate diverse groups of microorganisms.