Browsing by Author "Yapa, P.N."

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    Accumulation of Proline in Plants of Mangrove and Maritime Ecosystems in Southern Wet Zone of Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2019-02) Jayathilake, W.W.N.T.; Nallaperuma, N.A.W.R.; Yapa, P.N.
    Mangroves and maritime plants are the only halophytes living at the influence of land and sea, and occupy tropical and subtropical coastline. Mangrove and maritime communities are recognized as part of the marine ecosystem and are highly productive ecosystems. Saline habitats represent a physiological challenge for plants because of the highly negative water potential of the soil water, making water acquisition difficult. Osmotically active solutes such as mannitol, proline, glycinebetaine and triterpenoids are necessary to reduce water potential in cell cytoplasm. The present study was done with the objective of estimating the accumulation of proline in leaves of mangroves, mangrove associates and maritime plants in Southern wet zone of Sri Lanka. Proline concentrations in leaves of 12 mangroves, 5 mangrove associates and 15 maritime plants were measured by following the standard procedures with using UV/VIS spectrophotometer at 520 nm wave length. Further, proline concentrations were estimated in maritime plants of varying distances from the sea after plants were selected along the line transects of 200 m from the sea coast. Proline was accumulated in all tested mangrove, mangrove associates and maritime plant leaves with the varying concentrations. Among them significantly higher proline levels are found in the leaves of maritime plants Terminalia catappa, Flemingia strobilifera, Scaevola taccada, mangroves such as Nypa fruticans, Bruguiera gymnorrhiza and mangrove associate Anona glabra. Further, according to Pearson correlation analysis, there was no correlation observed on average proline concentration of maritime plants leaves and changing distances of 200 m from the sea coast (p= 0.477). An increment of proline accumulation was evident in majority of plant species of mangroves, mangrove associates and maritime vegetation in Southern wet zone of Sri Lanka under salt stress.
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    Screening for Antibacterial Potential of Marine Algae Extracts from West Coast of Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2019-02) Herath, H.M.B.M.M.D.; Yapa, P.N.
    Marine algae are produced wide variety of bioactive compounds and some of them can be used to development of antibacterial novel drugs. The present study was aimed to evaluate antimicrobial activity of some marine algae extracts from west coast of Sri Lanka. Pure cultures of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis and Pectobacterium carotovorum were used as the test microorganisms for antibacterial testing. Marine algae such as Ulva prolifera, Chaetomorpha antennina, Cladophoropsis sundanensis, Sargassum crassifolium, Asteronema breviarticulata, Chnoospora minima, Gracilaria multipartita, Gracilaria folifera, Gracilaria hikkaduwensis, Rhodopeltis sp., Grateloupia lithophila and Laurencia natalenis were collected from Kalpitiya sea coast. They were freshly ground and 25 g of each fresh algal sample was extracted in 50 ml of distilled water, methanol, acetone, diethyl ether separately and concentrated to 0.5 g/ml following solvent extraction at 30 oC. The test bacteria of 108 CFU/ml were introduced and uniformly spread on the surface of Muller Hinton agar plates separately and followed standard agar –gel diffusion inhibition procedure. After placing 25 µl of extracts into each well, plates were incubated at 37 °C and 30 oC respectively for 24 hours and the diameter of the growth inhibition zone around the wells were measured. Comparisons were performed using one-way ANOVA followed by Duncan multiple-range test. It was revealed that the all tested extracts of C. minima showed antibacterial activity against S. aureus and all extracts of G. folifera against E. faecalis. Methanolic, acetone and diethyl ether extracts of G. hikkaduwensis inhibited the growth of S. aureus. Further, methanolic extracts of A. breviarticulata, S. crassifolium and U. prolifera showed inhibitory effect against all tested bacterial species. Finally, it can be concluded marine algae from Kalpitiya coast of Sri Lanka are potential sources of bioactive compounds and should be investigated for identifying natural antibiotics.