Microbiology

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End date: 2019Has files: Yes

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Now showing 1 - 10 of 15
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    A preliminary study on application of phage-indicator model in evaluation of antiviral drugs
    (Sri Lanka Association for the Advancement of Science, 2015) Malalasekara, A.M.A.L.R.; Jayaratne, D.L.
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    Isolation and characterization of Rhodomicrobium vannielii from Winogradsky column
    (Sri Lanka Association for the Advancement of Science, 2015) Weerasingha, P.D.S.; Gunawardane, M.M.
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    Microbiological quality of ballast water discharged from ships arriving in Colombo inner harbour
    (Marine Environment Protection Authority, 2015) Jayasundera, C.D.; Rathnayake, I.V.N.
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    Ratoon stunting disease of sugarcane in Sri Lanka
    (Natural Resources, Energy and Science Authority of Sri Lanka, 1987) Jayaratne, D.L.; Widanapathirana, S.
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    Isolation and characterization of bacteria capable of degrading Polycyclic Aromatic Hydrocarbons
    (Sri Lanka Association for the Advancement of Science, 2013) Silva, S.I.D.
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    Effective biocide options for eliminating Ceratocystis spp associated with coir products
    (Sri Lanka Association for the Advancement of Science, 2011) Senavirathna, H.G.L.A.K.; Jayaratne, D.L.
    This study describes the determination of suitable methods for eliminating the fungus Ceratocystis associated with coir products. Ceratocystis spp is a pathogen causing diseases in several plants including coconut. The occurrence of this organism in coconut cultivations in Sri Lanka has been reported since 1906. Sri Lanka has extensive coconut cultivation and many coir products are exported. It is a quarantine requirement that the coir products are free from this organism. Currently, methyl bromide is used as a fumigant to eliminate the organism, but the use of this chemical is restricted due to its high toxicity and because it affects the ozone layer. In this study the organism was isolated from the coir dust samples collected from the areas of Lunuwila and Kurunegala. The morphological characters of spores were similar in the isolates obtained from these two different locations. However, the color of the chlamydospores was darker in the isolates obtained from Kurunegala than in the samples collected from Lunuwila. The effectiveness of the fumigant formaldehyde (37% formaldehyde 120 ml with 60 g potassium permanganate for 2.83 m3 or 100 ft3 air space) was tested in fumigation chambers parallel with methyl bromide (48 g/m3) on a Potato Dextrose Agar culture and in inoculated coir dust. The formaldehyde was effective for inoculated coir dust but not for the fungus grown on culture plates, while methyl bromide was effective for both. As an alternative method, water vapor heat treatment was applied at different time temperature combinations on coir dust inoculated with fungal spores. At 55 °C for 5 min., the vapor heat treatment destroyed the viable spores in it. For the elimination of Ceratocystis associated with coir dust, formaldehyde can be used in place of the currently used methyl bromide. Formaldehyde is less effective when the organism is grown on culture media due to the different conditions prevalent in culture media and coir dust. Besides the chemical formaldehyde, heat treatment can be applied for eliminating the organism. A temperature of 55 °C generated from water vapor for 5 minutes is sufficient for eliminating the fungal spores.
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    Study of the microorganisms in two Ayurvedic medicated oil preparations with special reference to microbiological quality standards
    (Sri Lanka Association for the Advancement of Science, 2010) Najeeb, B.M.; Amarasinghe, A.P.G.; Widanapathirana, S.
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    A microbiological study of an Ayurvedic compound preparation Dasamoola Arista with a view to defining an acceptable microbial quality standard
    (Sri Lanka Association for the Advancement of Science, 2008) Nageeb, B.M.; Widanapathirana, S.; Amarasinghe, A.P.G.
    The Indigenous system of medicine has been practiced successfully over several thousand years. The basic ingredients of indigenous medicine are plant materials. These materials contain natural inherent microbial flora and also may become contaminate during processing. Considering these facts the World Health Assembly in its resolutions WHA-31:33, 40:33, and 42:43 has emphasized the need for the microbial quality standard of medicinal plant products. Dasamoola Arista, has been used in therapeutics for several centuries. The objectives of this study were to enumerate the total viable count of bacteria, fungi and specific microorganisms such as Coliforms and Salmonella in the market samples of this drug. Fourteen different market samples were subjected to this study. Nutrient agar and Potato Dextrose agar were used as culture media. Pour plate and Spread plate techniques were used to study the microbial load in dilution series up to 10-3. Microbial counts on Nutrient agar and Potato dextrose agar were taken after 24 hours and 72 hours. Tests for Coliforms and Salmonella were done according to International standards. Coliform test was performed by MPN method using single strength MacConkey broth. Salmonella was tested after an enrichment process in buffered peptone. 0.1ml of this peptone was transferred to test tubes of Tetrathionate and Selenite broth separately and Incubated at 37 0C for 48 hours. These broths were streaked on Bismuthsulphiteagar (B/S.Agar) and Brilliantgreenbile agar(BGB ) Black colonies on B/S-Agar and Pink colonies on BGB Agar were considered as positive for Salmonella. These colonies were bio chemically tested for salmonella . All tests were repeated thrice and results were confirmed. The microbial load observed in this study was with in the limits of the WHA. The Colony count for Bacteria was in between 10x10 to 10x68. Fungi Colony count was in between 1x10 to 36x 10. The biochemical tests revealed that the Bacteria present in this preparation was Bacillus firmus. None of the drug samples were positive for Coliforms or Salmonella. These results revealed that these tested samples were microbiologically safe and up to the microbial quality standard.