Browsing by Author "Kulasooriya, S.A."

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    Investigating Variation of Microbial Biomass in Plantation Forests with Age
    (Uva Wellassa University of Srilanka, 2011) Premetilake, M.M.S.N.; Rathnayake, R.R.; Kulasooriya, S.A.; Perera, G.A.D.
    Note: See the PDF Version Soil organic carbon is the basis of sustainable agriculture and is important for chemical, physical and biological fertility. Consequently, carbon soil fertility could be improved more via sequestering. The role of microorganisms is important for carbon sequestration in soil compared to other factors. Thus, by increasing the activity of microorganisms we can increase carbon sequestration and soil fertility. Plantation forests were originally established in Sri Lanka to provide industrial timber and fuel wood. There are also other uses such as wind protection, bee keeping and oil extraction and moreover they provide invaluable ecosystem services. At present, sites available for reforestation in Sri Lanka are generally poor in nutrients and fertilizer application is required for better growth of seedlings. A novel approach of research at the IFS is the application of beneficial microbial consortia as biofilm biofertilizers for sustainable agriculture (Seneviratne et al., 2011). These are low cost and are eco-friendly. The shifts in composition and function of the microbial community in response to different stages of forest regeneration play an important role in determining rates of C changes (loss or gain) in the soil (Plante at al., 2005). Hence the long term goal of this study is to produce biofilm bio fertilizer for forest plantations to improve their yields. This would be more beneficial, less expensive and have no detrimental effects to the ecosystems. The biofilm bio fertilizer will be prepared using the microorganisms that have the capability of sequestering more carbon than the others. In this process, identification of the microorganisms and the factors affecting them is a crucial component. There are no studies conducted on this regard in Sri Lankan plantation forests yet. In the current study we investigated how the microbial biomass carbon (MBC) varies in Eucalyptus grandis forests in Sri Lanka with their age. Improved Carbon sequestration in forests would deliver better yields and would assist in minimizing climate change and support in obtaining foreign currency via carbon trading.
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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 economiĀ¬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.