Browsing by Author "Ratnayake, R.R."

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    Antioxidant Properties in Four Cyanobacteria sp., Isolated from Fresh Water Bodies of Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2016) Hossain, M.F.; Ratnayake, R.R.; Meerajini, K.; Premetilake, S.N.; Kumara, K.L.W.
    The aim of this investigation was to study the total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity, phycobiliproteins and active compounds in four cyanobacterial species, i.e., Oscilatoria sp., Lyngbya sp., Microcystis sp. and Spirulina sp. isolated from fresh water bodies of Sri Lanka. Water sample was collected from different fresh water bodies representing two climatic zones of Sri Lanka that is dry zone and wet zone and was filtered through 20 p.m planktonic net. The retentiate was cultured in BG11 and GO media recommended for cyanobacteria. Frequent sub culturing was carried out to isolate uni-algal culture. Isolates were identified morphologically under microscope (40X magnification). In the present study, Lyngbya sp., showed highest TPC (5.02+0.20 mg/g), TFC (664.07+19.76 mg/g) and total phycobiliproteins (127.01 mg/g) value. The ferric reducing antioxidant power (FRAP) was recorded highest in Oscillatoria sp. (39.63+7.02) whereas the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was also reported the highest in Oscillatoria sp. (465.31+25.76) followed by Lyngbya sp. (248.39+11.97). In FTIR spectroscopy Lyngbya sp. does not show any N-H stretching band which is ultimately responsible for the inhibition of antioxidant activity. The study revealed that Lyngbya sp. and Oscilatoria sp. can be an excellent source for food, pharmaceutical and other industrial use. Keywords: Cyanobacteria, Total Phenolic Content (TPC), Total Flavonoid Content (TFC), DPPH, FRAP, Antioxidant, Phycobiliproteins
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    Efficient Microorganisms for Bioethanol Production from the Natural Environment of Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2019-02) Jayasekara, S.K.; Abayasekara, C.L.; Ratnayake, R.R.
    Sri Lanka is biologically diverse. The potential of utilizing this rich biodiversity for sustainable socio-economic development of the country is extensive. The vast microbial diversity is a key component in biological diversity. However, the industrial scale application of native microorganisms is still underutilized. The objective of this study was to explore microbial flora of Sri Lanka to isolate efficient cellulolytic fungi and ethanologenic yeast for application in bioethanol production. Fifty fungi were isolated from soil. The total cellulase activity of fungal isolates was determined to compare cellulase production. Yeasts were isolated from local fruits viz: grapes, oranges and mangoes. Ethanol production by each yeast isolate was assessed in a glucose containing fermentation medium. Detection and quantification of ethanol were done by High Performance Liquid Chromatography (HPLC) using ethanol standards. The HPLC analysis was conducted using Milli-Q water in 0.6 ml/minute flow rate as the solvent. Hi- Plex H, 300×7.7 mm column was used with Refractive Index Detector for ethanol detection. Both were maintained at 55 ˚C temperature for the analysis. According to the results, the highest total cellulase activities were given by fungal genera Trichoderma, Aspergillus and Penicillium. Trichoderma viridae was the most efficient isolate giving a total cellulase activity of 0.574 FPU/ml followed by the Aspergillus niger, being the second most efficient cellulase producer with 0.464 FPU/ml total cellulase activity. Total cellulase activity of Penicillium oxallicum was, 0.438 FPU/ml, which was not significantly different from A. niger. Among six ethanologenic yeast, the highest ethanol concentration was given by Y3 isolate as 9.651% while Y5 showed 5.84 %. All the isolates reported ethanol yields above 2%. There is a great potential of applying these efficient isolates in bioethanol production because cellulolytic fungi can degrade cellulose to release fermentable sugars for yeast.
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    Isolation of Microflora and Changes of Carbohydrates of Certain Water Weeds through Senescene
    (Uva Wellassa University of Sri Lanka, 2010) Perera, O.S.; Ratnayake, R.R.; Kulasooriya, S.A.
    Water weeds have become an ecological and social problem in irrigation tanks, reducing the flow of water in irrigation and drainage channels, blocking sluice gates and points of water intake in power generating stations. Producing biofuels via biomass conversion to use them as renewable sources of energy alternative to fossil fuels would be an economi¬cal solution to control these weeds. "Microbial energy conversions" can be used to convert biomass into biofuel at low cost. This study aimed to isolate and identify the microflora that can be used in microbial energy conversions and to examine the changes of carbohydrates of certain water weeds through senescence. Three floating aquatic weeds; Eichhornia crassipes (water hyacinth), Salvinia molesta (water moss) and Pistia stratiotes (water lettuce) abundant in different climatic zones of Sri Lanka were utilized. Enrichment culture techniques were used to isolate the microorganisms. Bacterial isolates were identified to the genus level using biochemical tests and for fungi morphological characters were observed. Finally pure cultures were transfered to agar slants of suitable media for short term storage, and for long term maintenance they were presereved in cryo tubes and stored under -20 OC. Bacterial genera identified consisted Clostridium, Pseudomonas, Bacillus, Staphylococcus and Klebsiella while the fungal genera consisted Paecilomyces, Trichoderma, Acremonium and Cylindrocarpon. To analyse the carbohydrate composition (mainly cellulose and lignin), Fourier Transform Infrared Spectrometer (FTIR) was used. Cellulose and lignin were identified using FTIR absorbance peaks for bonds that are specific for these compounds. According to the FTIR absorbance peaks there were no qualitatative changes among the three species of water weeds or within the different stages of their growth. The statistical analysis of the different absorptivities of the water weeds showed that there is no significant different in Cellulose or Lignin among the three water weeds. When comparing Cellulose and Lignin mature Eichhornia crassipes had a significantly higher amount of lignin than cellulose at the 5% probability level.The Cellulose content is high in mature stage of Salvinia molesta than in young and senescence stages. This study was a prelude for the development of microbial energy conversions to produce bio-fuels from cellulosic biomass.
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    Soil Organic Carbon and Interdependencies among Soil Physio-Chemical Parameters of Mangrove Dominated Ecosystem at Palakaimunai in Mannar Region, Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2021) Dissanayake, D.D.M.O.; Jayasinghe, J.A.V.R.; Perera, G.A.D.; Kadupitiya, H.K.; Seneweera, S.; Ratnayake, R.R.
    Palakaimunai, positioned at North Western coast of Sri Lanka, has been shaped and influenced by oceanic, terrestrial and anthropogenic activities to varying extent. The natural vegetation in this deltatic system is dominated with mangroves with intermittently spreading saltmarsh patches at the foreground and littoral woodland species at the back. The extent which the mangroves in such seasonally dry tropical climates would provide sediment-grounds for soil carbon and other nutrients is yet to be revealed. Therefore, spatial variation of soil carbon and carbon fractions, and the associations of these to available nutrients in Palakaimunai mangals were examined in this study. Stratified random sampling adhering to 10 m × 10 m grids based on ArcGIS were laid and soil sampling (n=30) was done from the layer of 0-15 cm from surface. Samples were analyzed for available nitrate, phosphate and ammonium, microbial biomass carbon (MBC), permanganate oxidizable carbon (POC), water soluble carbon (WSC) and soil organic carbon (SOC), soil macro and micro nutrient cations. Principal component (PC) analysis and agglomerative hierarchical clustering based on geometric positioning under PCs revealed five clusters indendogram, despite there was a high spatial heterogeneity examined soil parameters over the area. Interdependencies were unreciprocated among pH (+) to SOC (-) and WSC (-) and ammonium (-) and zinc (-) to MBC (+). The samples in the clusters with the highest mean SOC content of 11.3%- 14.0% and was associated with low MBC (0.005% ± 0.007) , high POC (712.23 ± 6.97 mg/kg), high WSC (0. 15% - 0.16%) and high ammonium (14.2 ± 8.5 mg/kg) contents. Nevertheless, the samples in the cluster with the lowest SOC content of 1.99 ± 1.54 was found to be associated with the highest availability of nitrate (2.90 ± 0.78) and lowest of phosphate (14.98 ± 6.02 mg/kg) contents. These highest SOC contents were recorded at proximate substratum with Avicenia and Rhizophora species and within frequently saturated substratum. Simultaneously, low MBC content was related with the above prevailing aneroxic condition. Thereby, generalization over in-site SOC may not verify the carbon sink potentiality thus varied by geomorphological traits. Keywords: Blue carbon ecosystems; MBC; WSC; Cluster analysis; SOC