Science

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Author: search.filters.author.Kannangara, S.Has files: No

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    Polyaromatic Hydrocarbon Degradation of Moss Endophytic Fungi Isolated from Macromitrium sp. in Sri Lanka
    (David Publishing, 2016) Kannangara, S.; Ambadeniya, P.; Undugoda, L.; Abeywickrama, K.
    Polyaromatic hydrocarbons (PAHs), which are the major by-products of fossil fuel burning, are released to the environment with the immense growth of urbanization and industrialization. These pollutants are subsequently deposited on many substrates including plant surfaces. Due to their toxicity, mutagenicity, carcinogenicity and recalcitrant nature, they can result in many hazardous effects on human health. Application of endophytes in bioremediation has shown much promise in removing these PAHs from contaminated substrates. In the present study, an attempt was made to isolate and identify endophytic fungi from the moss plant Macromitrium sp. (frequently available) in Sapugaskanda (highly polluted) and Hettimulla (less polluted) areas in Sri Lanka. Subsequently, their potential in degrading PAHs (naphthalene and phenanthrene) was investigated. Endophytes from the moss were isolated following the surface sterilization method, and their physiological roles in degrading naphthalene and phenanthrene were carried out using plate assays, spectrophotometric and high-performance liquid chromatography (HPLC) analysis. Most of the endophytic fungi isolated from Macromitrium sp. were able to grow in Bacto Bushnell-Haas (BBH) medium incorporated with naphthalene and phenanthrene, separately, displaying colony diameters more than 30 mm. As per the results obtained from spectrophotometric and HPLC analysis, Penicillium oxalicum, Nigrospora oryzae, Aspergillus oryzae, A. aculeatus, Penicillium sp.1, Penicillium sp.5, Eupenicillium sp.2 and Mortierella sp.1 degraded both naphthalene and phenanthrene more than 85%. The findings of the present investigation provide some insight into how these endophytic fungi could be used for bioremediation of PAHs in environmental sites where contamination prevails, and also open avenues for future research in the relevant field.
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    Evaluation of antifungal effect of Croton aromaticus on storage life extension of banana
    (2016) Dilhani, S.; Wimalasiri, S.; Abeywickrama, K.; Kannangara, S.
    Effect of Croton aromaticus aqueous, hot water and ethanolic leaf extracts alone and in combination with alum against banana crown rot causing fungal pathogens were investigated using 96 well plate bioassay and liquid bioassay in vitro. According to the results of 96 well plate assay, C. aromaticus aqueous extract successfully inhibited conidial germination of C. musae up to 96.9%. Percentage germination inhibition of F. proliferatum is less than that of C. musae. Hot water extract expressed higher conidial germination inhibition of F. proliferatum. Conidial germination of C. musae was 100% inhibited at the concentration of 600 (%w/v) of ethanoic extract and at the same concentration F. proliferatum was inhibited by 90.4 %. Alum was fungicidal against C. musae and L. theobromae. C. aromaticus leaf extract in combination with alum controlled F. proliferatum more effectively compared to leaf extract alone. During liquid bioassay, ethanolic leaf extract totally inhibited the mycelial growth of test pathogens at the concentration of 800 (%w/v). Among three tested extracts, ethanolic extract was most effective in inhibiting both spore germination and mycelial growth of crown rot causing fungal pathogens.
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    Efficacy of basil oil and alum in controlling crown rot disease of Cavendish banana (Musa acuminata, AAA) during cold storage
    (2016) Siriwardana, H.; Abeywickrama, K.; Kannangara, S.; Attanayake, S.
    Effect of Ocimum basilicum (basil) oil spray treatment, alum in combination with modified atmosphere packaging (MAP) was investigated in extending the shelf life of Cavendish banana (Musa acuminata, AAA - Grand Naine cultivar) at 12-14 0C. Twelve week mature Cavendish banana fruits were treated with 1% (w/v) alum (Potassium aluminium sulphate), 1% (w/v) alum + 0.4% (v/v) basil oil, 0.5 g/L carbendazim and distilled water (control). Treated banana samples were packed in Low Density Polyethylene bags and stored at 12-14 0C. In-package gases were analysed every seven days up to 28 days of storage. 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 each storage period. At the end of 28 days of storage O2 in all packages remained between 5.0- 5.4% while CO2 varied from 5.1 to 5.6%. Further, treatment of 1% alum+0.4% basil oil effectively controlled crown rot disease of Cavendish banana completely up to 21 days. Most of physicochemical and sensory properties of treated banana were not adversely affected by the treatment.