International Research Symposium on Pure and Applied Sciences (IRSPAS)
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Item Isolation and identification of litter decomposing fungi in Nagacholai Forest Reserve, Mullaitivu, Sri Lanka(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Bopitiya, B. D. S. S.; Dewangani, H. G. N.; Perera, H. W. K.; Premachandra, J. A. H. P.; Senevirathna, M. A. T. M.; Kalpani, N. N.; Kodituwakku, T. D.; Kannangara, S.Nagacholai Forest Reserve, which was disturbed by local terrorism before 2009, is located in Mullaitivu District in the Northern Province of Sri Lanka. It is a tropical dry zone forest, administrated by the Department of Forest Conservation, Sri Lanka. Litter-fall and subsequent nutrient release from decomposing litter are crucial processes that regulate the nutrient availability and the nutrient cycling in soil, as well as the plant growth in forest ecosystems. Litter decomposition rates of forest ecosystems are governed by both biotic and abiotic factors. Therefore, the present study was conducted to study soil characteristics such as pH and electrical conductivity and to isolate and identify the litter decomposing fungi of the Nagacholai forest. Soil and litter were collected randomly by placing 0.5 m X 0.5 m size quadrats on the forest floor. The pH and electrical conductivity of each soil sample were determined by following standard methods. Litter decomposing fungi were isolated from leaf discs (1 mm X 1 mm) obtained from the collected litter following washing and plating method using sterilized distilled water. Pure cultures of isolated fungi were maintained at 28 °C in PDA and morphologically identified using identification keys. The low moisture content in the soil was reflected by brown colour, sandy-podzolic soil. The high proportion of less decomposed, dense litter layer reflected the low decomposition rate due to decelerated soil microbial activity and low water availability. Soil pH was within the range of 6.34 – 6.80 and electrical conductivity at 30 °C varied between 1.23 – 1.57 mS cm-1. Five different fungal species were isolated in high frequencies (50%>) from leaf litter, while four of them were identified up to the genus level based on their vegetative and reproductive morphology (i.e. Mucor sp., Aspergillus sp., Candida sp. and Pestalotiopsis sp.). The remaining unidentified species produced white colour colonies and branched, hyaline, septate hyphae without showing any sexual reproductive structure. Mucor, Aspergillus and Pestalotiopsis are some of the common fungal decomposers found in most of the forests of different climatic zones. However, Candida is a filamentous yeast, which is not frequently reported as a decomposer in terrestrial ecosystems, but found to be a member of the normal soil microflora in forests as secondary sugar fungi. Therefore, Mucor, Aspergillus and Pestalotiopsis could be identified as the most prominent genera of litter decomposing fungi in the Nagacholai forest. Nevertheless, this preliminary study needs to be elaborated further to confirm their identity up to species level using molecular techniquesItem Effect of Croton aromaticus leaf extracts in controlling Crown Rot disease of Embul banana.(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Dilhani, S.; Wimalasiri, S.; Abeywickrama, K.; Kannangara, S.Embul banana (Musa acuminata-AAB) is one of the major dessert fruits in Sri Lanka, widely consumed by all economic groups due to its small size and characteristic flavour. Although Embul banana has high potential for export market storage and export of this commodity over long distances is difficult in consequence of postharvest fungal diseases. The most common and serious postharvest disease that affect Embul banana is Crown Rot (CR). Use of synthetic fungicides is the widely used method in controlling postharvest diseases of fruits worldwide. The interest of finding natural bioactive components has increased due to the harmful effects of synthetic fungicides on environment and health. In the present study, antifungal activity of aqueous, hot water and ethanolic leaf extracts of Croton aromaticus in controlling CR disease of Embul banana was investigated in vivo. Embul banana hands (85-days mature) were treated with C. aromaticus aqueous, hot water 100% (v/v) and ethanolic leaf extracts (400 mg/ml) alone or in combination with alum (1%) or distilled water (control) were stored in modified atmosphere packaging at 12-14 0C for 14 days. Each treatment comprised of 4 replicates. In-package gases were analysed on initial day and thereafter up to 14 days. Physicochemical properties (pH, firmness, TSS, TA), sensory properties (peel colour, flesh colour, aroma, flavour, taste, overall acceptability), and Crown Rot disease severity were determined in ripening induced fruits after 7 and 14 days of storage period. Statistical analysis was done using the MINITAB 16 statistical package. Oxygen levels measured were observed to be amaintained at 2.2-4.4% while CO2 levels were maintained at 5.5-8.4% in all packages at the end of 14 day storage period. C. aromaticus ethanolic leaf extract (400 mg/mL) was the most effective extract in controlling crown rot disease of Embul banana compared to aqueous and hot water leaf extracts. Physicochemical properties of Embul banana treated with C. aromaticus leaf extract alone and in combination with alum were not significantly different compared to control except for TSS and TA. Most of the sensory properties were preferred by sensory panelists with score values of above 6 indicating the good quality of samples. C. aromaticus ethanolic leaf extract + alum in combination with modified atmosphere packaging and cold storage could be used as a potential safe way of controlling Crown Rot disease of Embul banana.Item A preliminary floristic study of Chundikulam forest reserve in Jaffna peninsula(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Ekanayake, G.C.M.; Medhavi, P.I.H.R.; Somasiri, R.P.I.V.; Jayalath, W.G.H.; Siriwardhana, K.H.W.; Samarasinghe, D.G.S.N.; Kannangara, S.Chundikulam sanctuary is a reserve which is located in the Northern Province, in Jaffna peninsula. This reserve is situated in the dry zone of Sri Lanka and the area consists of mangroves along the shores and scrub lands in the sandy areas. The Jaffna peninsula, including Chundikulam, faced an ecological destruction due to the Sri Lankan civil war which prevailed for almost three decades. Therefore, due to the paucity of data of this arid vegetation, this current study was carried out as the first investigation after war. According to the surveys, Chundikulam covers an area of 19,000 hectares in vegetation. A systematic study on the vegetation of this dry arid zone forest was carried out using randomly selected representative sampling sites to document the vegetative diversity of the region, through a field survey conducted in the peripheral areas of this reserve in March 2016. Five quadrates (10m×10m) per site were placed totaling to 25 random sample collections. Eighteen different plant species were collected during the study and herbarium specimens were prepared and submitted to the Department of Botany herbarium, University of Kelaniya, Sri Lanka. The plant species sampled were trees (8 species), shrubs (4 species) and creepers (6 Species). Among them Carissa spinarum, Borassus flabellifer, Drypetes sepiaria, Stereosperum colais, Prosopis juliflora. Dillenia sp., Pterocarpus sp. were tree species and Atalantia ceylanica,and Memwcylon umbellatum were recorded as shrubs and Euphorbia antiquorum, Jasminum officinale, Hardenbergia sp. were identified as creepers. The dominant plant species of the vegetation was Drypetes sepiaria (Putranjivaceae) while Borassus flabellifer (Arecaceae) was the most abundant.The total vegetation cover was estimated by the mean number of individuals (30.4%). The plant communities that have been recognized in this study within the arid and dry forest in Chundikulam forest reserve will provide preliminary scientific data for a systematic review of the changes in their vegetation after the war which prevailed for almost three decades.Item Screening endophytic fungi of Macromitrium sp. for potential degradation of PAHs(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Ambadeniya, A.R.P.D.U.K.R.; Kannangara, S.; Abeywickrama, K.With rapid industrialization and urbanization, emission of air pollutants to the atmosphere has been increasing rapidly for several decades. Out of many pollutants, polyaromatic hydrocarbons (PAHs) take a prime advertence due to their toxicity, mutagenecity, carcinogenicity and long persistence in nature. Therefore, removal of these is one of the major cruxes that the modern world faces. In the present study, an effort was made to isolate and identify endophytic fungi in a moss (Macromitrium sp.) found in a polluted area (Sapugaskanda) and a less polluted area (Hettimulla), and to investigate their ability to degrade PAHs (naphthalene and phenanthrene). It was hypothesized that endophytes isolated from the moss can degrade PAHs and endophytes from polluted area have a higher ability to degrade PAHs compared to those isolated from the less polluted area. Moss plants from Sapugaskanda and Hettimulla area were used. Surface sterilized and trimmed moss plant pieces were placed on Malt Extract Agar and incubated for 10 days at room temperature. Percentage frequency of occurrence of each fungus grown was calculated. Utilization and degradation of PAHs by each of the fungus was assessed using a plate assay and a spectrophotometric analysis. Thirty six isolates were recovered from samples from Sapugaskanda area, 21 from Hettimulla and 6 were common to both areas. Highest frequency of occurrence was observed in Eupenicillium sp.2 (95.0%) in samples from Sapugaskanda and white sterile sp.7 (32.5%) for Hettimulla. Highest PAH utilization with the highest colony diameter, was recorded for Nigrospora oryzae for naphthalene (85.2 mm) and phenanthrene (59.5 mm). Almost all isolates from Hettimulla demonstrated low colony diameters. According to spectrophotometric analysis, highest degradation was observed with Penicillium oxalicum for naphthalene (98.60%) and Nigrospora oryzae against phenanthrene (98.02%). Almost all isolates in samples from Hettimulla area displayed poor degradation ability. The findings of the current study clearly reveal that Macromitrium sp. in Sapugaskanda harbours higher number of endophytic fungi than that in Hettimulla and most of them have a considerable ability to utilize and degrade PAHs in contrast to that in Hettimulla. It could be speculated that those endophytic fungi in Macromitrium sp. of Sapugaskanda, could be potential sources of fungal bioremediation. Further, they have potential practical application in removing PAHs from contaminated sites.Item Assessment of phytochemicals and antifungal effect of Croton aromaticus against postharvest fungal pathogens isolated from tropical fruits(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Wijesundara, S.A.D.T.L.; Kannangara, S.; Abeywickrama, K.Chemical control using synthetic chemical fungicides is still the most common method of controlling postharvest diseases of fruits. Plant extracts which are rich in antimicrobial secondary metabolites such as terpinoids, alkaloids, saponins and flavonoids could be possible alternatives for synthetic fungicides. Current study was focused on evaluating the antifungal effect of ethanolic extract of Croton aromaticus (Kappettiya) leaves in vitro against mycelial growth and the spore germination of postharvest fungal pathogens isolated from fruits of banana (Colletotrichum musae, Rhizopus sp., Lasiodiplodia theobromae) papaya (Rhizopus stolonifer, Colletotrichum gleosporioides, Lasiodiplodia theobromae) and mango (Alternaria alternata, Pestalotiopsis mangiferae, Lasiodiplodia theobromae). Surface sterilized diseased banana, papaya and mango fruit tissues were cultured on PDA plates in order to obtain pure cultures of possible fungi and they were identified by morphological and microscopic characteristics, using identification keys. Inhibitory effect of the ethanolic extract of C. aromaticus against test pathogens were investigated by well diffusion method using PDA medium, by incorporating crude extract dissolved in DMSO, ranging from 1 mg/ml up to 300 mg/ml concentrations along with the positive (Captan) and negative (DMSO) controls. Significant (P < 0.05) inhibitory effects were exhibited by the ethanolic extract of C. aromaticus leaves against all test pathogens except L. theobromae. The highest mycelial growth and spore germination inhibition of most of the pathogens were observed at 100 mg/ml. The lowest Minimum Inhibitory Concentration of the leaf extract (5 mg/ml) was observed for spore germination inhibition of C. gleosporioides and P. mangiferae. TLC analysis revealed four compounds having Rf values of 0.551, 0.672, 0.810 and 0.913. Phytochemical screening of ethanolic extract revealed the presence of alkaloids, terpenoids, quinones, phytosterols and flavonoids. Current findings indicate the potential use of ethanolic extract of C. aromaticus leaves in controlling banana, papaya and mango postharvest fungal pathogens in vitro.