Science

Now showing 1 - 2 of 2

Anti-oxidant activity of selected endo lichenic fungi (ELF) in mangrove ecosystem of Puttalam lagoon.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Maduranga, H.A.K.; Attanayake, R.N.; Amarasinghe, M.D.; Weerakoon, G.; Paranagama, P.A.
Natural products based drug development has become an attractive area of research since there are limited options available to treat certain non-infectious diseases such as diabetes. Among these natural products, it has been reported that secondary metabolites of endolichenic fungi (ELF), have the ability to produce promising bioactive compounds. The objectives of this research were to isolate and identify ELF inhabiting mangroves in Puttalam lagoon, Sri Lanka using classical and DNA barcoding approach and to determine anti-oxidant activity of their secondary metabolites. Lichen hosts were collected from Puttalam lagoon in two different sites near, Athathale and around the NARA institute. The ELF were isolated following a standard procedure: a small piece of the thallus was surface sterilized, cut into pieces and dried on sterilized filter papers and then placed on malt extract agar in Petri dishes and incubated at room temperature (28 ⁰C – 30 ⁰C ) . Once pure cultures were obtained, seven isolates were randomly selected for DNA extraction following standard procedures. Quality of DNA was checked by agarose gel electrophoresis. Fungal internal transcribed spacer (ITS) region was amplified using polymerase chain reaction (PCR) with universal ITS 1 and ITS 4 primers and PCR products were sequenced using Sanger dideoxy chain-termination technology. DNA sequences were edited using BioEdit software and compared with the available sequences in the GenBank using Basic Local Sequence Alignment Search Tool (BLAST). In addition, morphological characterization of each fungal isolate was also carried out. Secondary metabolites from each isolate were extracted with ethylacetate separately and the solvent was evaporated under reduced pressure to obtain the crude extract. Free radical scavenging activity of the extracts were evaluated using 2, 2-diphenyl-1-picrylhydrdrazyl (DPPH) assay. Based on the highest sequence similarity to the GenBank sequences, isolates were identified as Diaporthe arengae (98 %), Neurospora crassa (100%), Lasiodiplodia theobromae (100 %), Schizophyllum commune (98 %), Diaporthe musigena (98 %), Hypoxylon anthochroum (98 %) and Nigrospora sphaerica (98%). IC50 values of extracts of Diaporthe arengae, Neurospora crassa and Lasiodiplodia theobromae were 375.9± 0.062μg/mL, 304.9±0.057 μg/mL and 211.2± 0.086 μg/mL respectively. Since percent inhibitions of the rest of the isolates were less than 50 % in the test doses, IC50 values were not calculated. All of the values were compared with standard Butylated Hydroxy Toluene (BHT) (IC50=108.0±0.072). Out of the seven ELF tested, L. theobromae showed the highest DPPH radical scavenging activity. Further testing of the rest of the isolates are being carried out and ELF may provide a good source of antioxidants for biotechnological applications.
Carbon retention capacity of two mangrove species, Bruguiera gymnorrhiza (L.) Lamk. and Lumnitzera racemosa Willd. in Negombo estuary, Sri Lanka
(Faculty of Graduate Studies, University of Kelaniya, 2012) Perera, K.A.R.S.; Sumanadasa, W.A.; Amarasinghe, M.D.
Carbon accumulation/sequestration by plants is a major function that contributes to removal of carbon dioxide from the atmosphere and capacity to perform it depends on the plant species and environmental conditions under which they live. Carbon retention by natural ecosystems such as mangroves therefore‚ is considered a crucial ecological service‚ and valued highly under the current global context of continued increase in greenhouse gas emission and associated climate change, on which marginal effort has hitherto been spared over its quantification. The Present study was conducted to characterize two true Sri Lankan mangrove species, i.e. Bruguiera gymnorrhiza (L.) and Lumnitzera racemosa Willd.,. with respect to their carbon retention capacity, and to develop allometric relationships between biomass of plant components and stem diameter at breast height (dbh) of the two species with a view to assisting quantification of carbon-sink function of mangrove ecosystems. Fourteen trees of B. gymnorrhiza, and ten trees of L. racemosa that represented the range of dbh distribution in the mangrove area at Kadolkele in Negombo estuary were selected, harvested and dry weights (biomass) were obtained of the components based on wet:dry weight. Organic carbon in samples taken from each plant component of the two species was determined using dichromate oxidation and colorimetry using spectrophotometer. Partitioning of biomass between above (A) and below (B) ground components is approximately 3:1, revealing that the pattern resembles more of that of terrestrial plants (A/B = 3.9-4.5) than mangrove species in higher latitudes (A/B = 2-3). A positive correlation (p<0.01) and non-linear relationship (linear log-log relationship) was revealed between dbh and biomass (component and total) of the two species and allometric equations were derived that could be used to quantify carbon-sink function of mangrove ecosystems comprised of these species and the potential of mangroves in carbon mitigation programmes with financial incentives for mangrove conservation. The average amount of carbon retained by an individual was 9.16 kg per tree and thus the total organic carbon retained by L. racemosa in the mangrove ecosystem in Kadolkele was 9.44 t/ha while that of B. gymnorrhiza, was 5.6 t/ha, despite its greater capacity of individual carbon retention (13.76 kg per tree) due to its relatively low density and basal area. L. racemosa contains higher percentage of carbon in the stems, branches and roots than B. gymnorrhiza revealing its superior contribution to carbon-sink function of mangrove ecosystems

Science

Browse

Filters

Settings

Sort By

Results per page

Search Results