Browsing by Author "Premathilake, M.M.S.N."

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    Antibacterial Activity of Silver Deposited Vein Graphite Against Waterborne Pathogenic Escherichia coli Synthesized by Chemical Reduction Method
    (Uva Wellassa University of Sri Lanka, 2019) Kumari, T.D.D.; Swarnamali, V.M.R.; Amaraweera, T.H.N.G.; Premathilake, M.M.S.N.; Wijayasinghe, H.W.M.A.C.; Balasooriya, N.W.B.
    Graphite is one of the common materials using for the fabrication of composite materials. Graphite oxide, graphene oxide and many other materials are used as effective antibacterial substances, but most of them are expensive and need highly toxic chemicals for the synthesis. Nowadays, silver is considered as a most effective antibacterial material. Therefore, this study was focused on synthesizing cost effective less hazardous antibacterial material using silver and graphite. Graphite sample was purified by acid leaching, followed by modifying the surface with Conc. HNO3. The silver graphite composite material was synthesized using AgNO3 as precursor and tri-sodium citrate as reducing agent. X-ray diffractometry and Scanning electron microscopy investigations of the synthesized silver graphite composite revealed that the pure crystalline nano silver particles were deposited on the graphite surface. Antibacterial efficacy of the synthesized material was investigated using waterborne pathogenic Escherichia coli. The antibacterial test was carried out against E. coli using prepared composite samples according to the shake flask test. A commercial antibiotic (Ofloxin-200 mg) was used as the positive control. The samples were drawn at times 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5 and 6 hours by counting the number of surviving bacterial colonies on Eosin Methylene Blue (EMB) Agar, using plate count method according to standard procedures. After 24 hours, the results showed that surviving bacterial colonies contained in counted petri plates of all the synthesized composites with different Ag: Graphite ratios were reduced, with the time in an efficiency of over 98%. Therefore, this study suggests that Ag-vein graphite composite synthesized via chemical reduction method can be effectively used as an antibacterial agent against E. coli.
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    A Biological Treatment for Color Removal in Distillery Effluents
    (Uva Wellassa University of Sri Lanka, 2013) Dilini, L.M.L.; Premathilake, M.M.S.N.; Udagedara, D.T.
    Distilleries are one of the industries generating enormous amount of wastewater which is about 10–15 L of effluent for the production of 1 L of alcohol. The fermentation of carbohydrates present in molasses is carried out by yeasts, which yields ethyl alcohol. The pH of the raw molasses is adjusted to 4 - 4.5 to prevent bacterial growth and then fermented liquor containing alcohol is degasified and alcohol is separated, leaving behind the waste called “spent wash”. The spent wash is the major polluting waste of the distillery, which has very high Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) values. The COD often crosses and BOD reaches7×10 mgL (Goel, 2006).The waste is dark brown in color due to caremalization of some sugar. It also contains nearly 2% of the dark brown recalcitrant pigment called melanoidin, which does not get degraded easily by microorganisms, posing a great difficulty in its removal. Molasses has very high quantity of fermentable sugars. These sugars react with amino acids and undergo Maillard reaction and then polymerize to form melanoidin, which is a major color containing compound in the distillery effluent. Putrescible organics like skatole, indole and other sulfur compounds produces obnoxious smell in the effluent and when it comes in contact with high temperature, becomes more toxic to aquatic biota. The waste has substantial quantities of dissolved solids and suspended solids with high . The pH of spent wash remains in the acidic range varying from 3 to 5.4 (Goel, 2006). The distillery waste also has high quantities of potassium along with sulphates. Melanoidin containing distillery effluents require pretreatment before safe disposal into the environment, because the direct disposal causes serious soil and water pollution by inducing coloration and eutrophication problems in aquatic environments- which leads to reduction of sunlight penetration in water bodies. Additionally, it in turn decreases both photosynthetic activity and DO concentration affecting the normal life cycle of aquatic fauna and flora (Goel, 2006). Further, it causes reduction in soil alkalinity, inhibition of seed germination and damage to vegetation upon land disposal. Treatment of distillery wastewaters by physical or chemical methods was found not feasible due to the high cost and generation of secondary pollutants. But compared to them biological treatments are more economical and environmental friendly. Many fungi species have the ability of removing color from wastewaters. Especially white rot fungi exhibit extensive bioremediation activities that are mainly based upon their capabilities to produce extracellular lignin modifying enzymes (Pant and Adholeya, 2007). In this research we studied several white rot fungi activity towards decolorization of distillery effluents. Methodology Ten polyporusbasidiomycetes white rot fungi species were collected for distillery waste water treatment from Matara area.Effluent was collected from Pelwatte distillery inButtala. Effluent was dark brown in color, semi liquid and a dense material. About 5mm squares were cut from collected basidiocarps and placed on PDA plates and were incubated for 7 days. Among them, five fungal species were selected for the experiment due to their rapid growth. Above efficiently growing five fungal specieswere isolated using streak plate method. Streaked cultures were incubated again for 7 days.Then, using these cultures new plates were prepared by spread plate method incubatingagain for seven days.
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    Comparison of Antimicrobial, Antioxidant and Total Phenolic Content of Leaves of Solanum torvum, Solanum incanum, Solanum violaceum Grown in Two Different Areas of Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2020) Rajapaksha, R.P.A.D.; Premathilake, M.M.S.N.
    The present study was carried out to compare the antioxidant activity, antibacterial activity, and total phenolic content of the leaf extracts of Solanum torvum, Solanum incanum, and Solanum violaceum and to identify the effect of geographical area on the selected chemical properties to utilize them in medicinal purposes effectively. Three mature leaf samples for each variety were taken from three different locations of Badulla and Puttalam district and Methanolic extracts of shade-dried leaf powder were prepared. The antioxidant activity was determined using DPPH spectrometric assay. The antibacterial activity was investigated using agar disk diffusion assay against Escherichia coli and Staphylococcus aureus with Gentamicin as positive control and Methanol as the negative control. Folin Ceocalteu method was used to determine the total phenolic content of selected plants. S. torvum growing in Badulla district has shown the highest total phenolic content (163.4 GAE/g) and highest antioxidant activity (IC 50 value, 0.72 ppm). All the extracts tested were not active against E. coli. However, extracts of S. torvum in Badulla district were active against S. aureas (Average Inhibition Diameter, 7.33 mm; Positive Control, 24 mm; Negative control, 0 mm). According to statistical analysis, there is no significant difference in antioxidant activity and total phenolic content of the studied varieties and no significant effect from geological area to any of the studied properties (Two-way ANOVA, p >0.05). Since S. torvum of Badulla district has shown comparatively higher antioxidant activity, antibacterial activity, and total phenolic content, it could be more effective in the production of various medical commodities. However, further studies should be done for S. torvum growing in other areas as well. Keywords: Solanum sp., Antioxidant activity, Anti-bacterial activity, Total phenolic content, Geographical area
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    Development of High Nutritious Value Added Bread from Composite Flour
    (Uva Wellassa University of Sri Lanka, 2013) Fernando, L.T.I.; Peries, C.M.; Henagamage, A.P.; Premathilake, M.M.S.N.
    Bread is a popular bakery product across the whole cross profile of the society, where all consumers like to consume bread alike, regardless of the level of income, education and other demographic characteristics (Lohano et al., 2010). Conventionally, flours used in bread making are made from cereals, mainly wheat (Nnabuk et al., 2012). Wheat is a foreign origin commodity and substantial amount of foreign exchange is required to import this food item, which is a real burden to the national coffer. Due to the drop in production of wheat internationally the future pricing of this product will be very uncertain and increasi ng prices will be forecasted (Piyasena et al., 1996). The government of Sri Lanka is also discouraging the consumption of wheat based products by mainly reducing the wheat flour usage by 20% and mixing with flour obtaining from various other sources could be used in order to save the massive amount of foreign exchange (Piyasena et al., 1996). In recent years, the demand to use novel sources as substitute for the wheat flour has increased to provide the consumers requirements. Replacement of wheat flour by other kinds of flour in bread making is economically important in Sri Lanka. There is a growing interest in using composite flour for bread making owing to some economic, social, and health reasons (Adeyemi and Idowu, 1990).The composite flours used were either binary or ternary mixtures of flours from some other starchy crops with or without wheat flour. Previous studies have given successful evidences for the substitution of 10 % cassava flour to wheat flour as the composite flour mixture for bread making process (Adeyemi and Idowu, 1990; Dhingra and Jood, 2004). Therefore, this study was focused to develop a high nutritious bread by partially substituting wheat flour with composite flour mixtures made out of Caryotaurens (Kithul) and Xanthosoma sagittifolium (Kiriala) flour. Methodology This study was designed to assess the quality of bread produced with composite flourobtained from wheat, X. sagittifolllium and C. urens. Matured X. sagittifolllium tubers and C. urens flour were obtained as raw materials and X. sagittifolllium tubers were further processed to obtain the flour. Six blends were prepared by homogenously mixing wheat, X. sagittifolllium and C. urens flour according to the percentage proportions, 100:0:0 (A), 50:50:0 (B), 50:0:50 (C), 50:40:10 (D), 50:30:20 (E), 50:20:30 (F), 50:10:40 (G) respectively. The dough mixtures with different blends were kept in a mold for 90 minutes at room temperature followed by baking in a pre-heated oven at 250°C for 30 minutes. Physical parameters such as loaf weight, loaf volume, specific volume and sensory attributes (i.e. crust and crumb color, taste, aroma, texture and overall acceptability) were evaluated by using 30 untrained panelists. Sensory data were statistically analyzed using Friedman Test with the confidence level of 95% using MINITAB 15. Proximate analysis and cost analysis were investigated for the selected bread sample in order to evaluate the nutritional quality and the total cost. Further, microbiological analysis (bacterial count, yeast and mold count) and shelf life analysis were performed for the selected best sample under the refrigerated condition and room temperature conditions separately.
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    Garnet rich mineral sand based filter media for Removal of fresh water algae
    (Uva Wellassa University of Sri Lanka, 2018) Siriwardhana, K.A.J.W.; Amaraweera, T.H.N.G.; Premathilake, M.M.S.N.
    Algal blooms have become a stigma for present day stagnant surface water bodies. Therefore, consumption of water without treatment would be harmful. Garnet granules have the ability of reduction of bed expansion and particle abrasion in multi-media filters during back flushing due to its high specific gravity and high hardness. In this study, garnet granules separated from beach sand in southwestern costal area in Sri Lanka were investigated as a filter media to remove fresh water algae. Microscopic and particle size analysis indicated that the beach sand consists predominantly of garnet, quartz and ilmenite. The garnet grains are round to elongate shaped in the size range between 1 mm and 0.15 mm. Particle size and shape of the extracted garnet are optimum for the use as water filtering medium. Garnet enrich fraction grains (1 mm — 0.15 mm) were further concentrated by density separation via panning. Algae samples from Beira Lake, Colombo were collected, in the depth at illumination level 1% from surface. Algae were grown giving nutrient, sunlight and aeration. Nutrient medium used was the Bristol solution. For varying flow rates, algae filtered through 0.50 mm and 0.15 mm sieved fractions. Parallel determination for the efficiency of the filter bed with time was done and turbidity was measured by turbidity meter. When considering the algae filtration, removal of Microcystis is efficient for 0.15 mm panned fraction. Removal of Closterium was not efficient probably due to shape of the organism. Chroococcus and Volvox, were not removed well possibly due to their small size. Removal of algae was decreasing with the time from both filter beds. The study concludes that prepared garnet filter is useful in filtering Microcystis and further modifications should be done prior to use as a filter. Keywords: Algae, Garnet, Panning, Filtration, Mineral sand
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    Synthesis of Silver - Graphite Composite via Ultrasonication Associated Chemical Reduction and Study of its Antibacterial Properties
    (Uva Wellassa University of Sri Lanka, 2020) Gamlath, J.G.V.I.; Swarnamali, V.M. R.; Amaraweera, T.H.N.G.; Premathilake, M.M.S.N.; Wijayasinghe, H.W.M.A.C.; Balasooriya, N. W. B.
    Graphene oxide is widely used to produce an antibacterial silver composite, but mostly required toxic chemicals for production and they are comparatively expensive. The present study was focused on synthesizing cost-effective less hazardous antibacterial composite using vein graphite and silver. Silver graphite composites can be made using various methodologies and those methods can affect the antibacterial property. Therefore, in this study, silver graphite composite was synthesized by ultrasonication associated chemical reduction method. Sri Lankan vein graphite was purified by the patented acid leaching method, then surface modified with patented mild chemical oxidation method. The silver-graphite composite was synthesized from an AgNO3 silver precursor with a concentration of 0.00025 M, 0.001 M, 0.002 M by using tri-sodium citrate as a reducing agent. X-ray Diffractometry analysis indicated that composite only consists of silver nanoparticles and carbon in pure crystalline form. The composite was characterized by Scanning Electron Microscopy. Nano-scale silver particles were seen deposited on the surface of graphite. Antibacterial efficiency of the synthesized composites was analysed using Escherichia coli and the test was carried out using the shake flask method. For positive and negative controls, modified graphite and commercial antibiotic ofloxacin were used respectively. The samples were drawn out with a one-hour time interval from 0 to 6 hours and the number of surviving colonies on Eosin Methylene Blue agar was counted after 24 hours of incubation. The removal of the Colony Forming Unit for all samples gave efficiency over 99 %. The Kruskal-Wallis test suggests that colony removal depends on the time and concentration of AgNO3 used in the synthesized composite. Therefore, this study suggested that silver-graphite composite synthesized via ultrasonication associated chemical reduction can be used for E. coli as an effective antibacterial agent. Keywords: Graphite, Silver nanoparticles, Ultrasonication, Chemical reduction, Trisodium citrate