Browsing by Author "Kannangara, Sagarika"

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Exploration of Nephrotoxic Heavy Metal Contaminants in Edible Fish and Reservoir Sediments Linking with CKDu Prevalence of Sri Lanka
(2024) Dayananda, Nalika; Liyanage, Janitha; Kannangara, Sagarika
Inland fish is one of the main protein sources of the regular diets of remote communities in Sri Lanka where the incidences of Chronic Kidney Disease of unknown etiology (CKDu) have significantly increased. Nevertheless, the presence of nephrotoxic heavy metals in reservoir sediments poses a potential threat to the local ecosystem, particularly impacting the aquatic food web and fish populations. To study the problem, concentrations of heavy metals (Cd, Pb, As, Cr, Cu, Zn, and Mn) in two common edible wild and commercial inland fish species and associated reservoir sediments were investigated in selected CKDu endemic and non-endemic areas in Sri Lanka. The concentrations of heavy metals were 1,000 times higher in sediments than in dorsal fish muscles. Based on SQGs, Sediment-bound As, Cu, Zn, and Cd contents which exceeded the Effect range-low and median levels, implicated the harmful biological impacts to the living organisms inhabiting the Ulhitiya reservoir in the CKDu hotspot, including fish. Significant strong correlations in Cd, Pb, and Zn between the reservoir sediments and dorsal muscles of E. suratensis and O. niloticus confirmed that presume. Calculated Hazard Indices (HIs) were higher in E. suratensis (wild species) than O. niloticus (commercial species) irrespective of the location, and nephrotoxic heavy metals, including Pb, Cd, and As in fish muscles, contributed about 80% to the HI. Whether the estimated Target hazard quotients (THQs) for fish consumption were very much less than the threshold of 1, a relative possibility of the occurrence of chronic kidney failure of CKDu can exist due to exposure to the nephrotoxic heavy metals such as Pb, Cd, and As via fish consumption in the selected CKDu prevalence area. While a pollution event into an inland reservoir is often transitory, the pollutants' effects may be long-lived due to their tendency to be absorbed in the sediments and then released into the food chain. Even though detected heavy metal contents have complied with acceptable limits for human consumption, long-term consumption as the main animal protein source can directly impact the prevalence of CKDu among the residents in CKDu endemic areas in Sri Lanka.
Hydrolysis of fish waste using fruit wastes of Ananas comosus and Carica papaya for the formulation of liquid fertilizers
(International Journal of Recycling of Organic Waste in Agriculture, 2021) Ratnayake, R M C S.; Kannangara, Sagarika; Ranasinghe, Achala.
Purpose Fish waste is a protein-rich source that can be used as a value-added product in the formulation of organic liquid fertilizers. This study carried out to investigate the utilizing potential of fruit wastes of Ananas comosus and Carica papaya that contain bromelain and papain as major proteases in order to hydrolyze fish waste proteins to fulfill plant nitrogen requirements. Method Proteases were extracted from A. comosus (leaves, crown, unripe fruit pulp, ripe fruit peels and pulp) and C. papaya (leaves, ripe fruit peels and unripe fruit peels). The optimum temperature and pH for the enzymatic activities were determined. Four liquid organic fertilizers were produced with hydrolyzed fish waste that enriched by adding Gliricidia sepium, Chromolaena odorata, Tithonia diversifolia, Mikania scandens and coconut husk-ash. Fertilizers were tested on the growth of Basella alba comparing with a standard fertilizer. Results Ananas comosus ripe fruit peels and the mixture of (A. comosus + C. papaya) showed the highest enzyme activities (0.33±0.02 and 0.36±0.01 U mL-1 enzyme respectively) at 55 oC and 70 oC. The optimum pH for all the studied extracts was 7.5 at 37 oC. The highest plant fresh and dry weights were recorded in the foliar-applied fertilizer produced by hydrolyzing the fish waste using A. comosus and C. papaya, showing no significant differences to the standard fertilizer. Conclusion Hydrolysis of fish waste using the fruit wastes of A. comosus and C. papaya could be effectively used as an organic fertilizer for the growth of B. alba that leads towards sustainable waste management.
The mycoremediation potential of phyllosphere fungi in urban ornamental plants in Sri Lanka with mathematical models for PAH degradation
(2024) Dharmasiri, Nadeema; Kannangara, Sagarika; Undugoda, Lanka; Munasinghe, Jayantha; Madushika, Ruvini; Thambugala, Kasun M.; Gunathunga, Chathuri; Pavalakumar, Dayani
Currently, phylloremediation has emerged as a highly effective method for eliminating air pollutants, particularly polyaromatic hydrocarbons (PAHs). When PAHs accumulate on the phyllosphere, they significantly impact the fungal communities residing on leaf surfaces. This study aimed to investigate how pollution distribution patterns affect the diversity and PAHdegrading abilities of phyllosphere fungi, alongside identifying suitable mathematical models for PAH degradation. Leaf samples from two locations, Maradana and Sapugaskanda, were identified as having the highest PAH concentrations through principal component analysis. The fungal diversity in these highly contaminated regions was varied, with dominant species exhibiting greater PAH-degrading capabilities than those in less polluted areas. Thirty-five morphologically different epiphytic fungal strains were isolated on Potato Dextrose Agar (PDA) medium using the sample leaf wash. Two different fungal strains were selected as the best PAH degraders among those 35 different strains. These fungal strains were identified as Trichoderma harzianum P4M-16, and Fusarium solani P11M-46 based on ITS sequence data. Notably, these fungal species were more prevalent in highly polluted urban areas compared to less contaminated sites. High-Performance Liquid Chromatography (HPLC) analysis revealed that these two fungal species degrade PAHs more efficiently than others. Their kinetics assays demonstrated alignment with four degradation models when breaking down phenanthrene, naphthalene, pyrene, and anthracene. Scanning electron microscopy images showed that these fungi function as endophytes, extending their mycelium into the core leaf tissue layers beyond the epidermis. Gas Chromatography-Mass Spectrometry (GCMS) analysis indicated
Nature and activities of microfungi associated with the decomposition of rice straw in Sri Lanka
(Asian Journal of Agriculture and Biology, 2022) Undugoda, Lanka; Kannangara, Sagarika
Agricultural sustainability through crop residue biodegradation is an eco-friendly method to enrich soil fertility essential to agricultural countries. Rice straw, rich in cellulose, is the primary source of organic matter, enhancing the fertility in rice fields and is a better alternative to replace chemical fertilizer usage. Therefore, this attempt is to isolate and identify different genera of straw degrading microfungi efficient in lignocellulose biodegradation. Rice straw degrading fungal species were isolated from the partially degraded rice straw collected from selected areas in Sri Lanka, following the washing and plating techniques. They were identified into the genus level using standard identification keys, and their capacity to degrade cellulose, starch, lignin, and pectin were evaluated using substrate-specific testing protocols. Eighteen fungal species in the genera of Aspergillus, Chaetomium, Cunninghamella, Goidanichiella, Penicillium, Rhizomucor, Rhizopus, Stachybotrys, and Trichoderma were isolated from the partially degraded rice straw collected from different areas of Sri Lanka. Three Trichoderma species showed significantly the highest frequency of occurrences (40%, 45%, and 43% respectively) in rice straw and a homogenous distribution among the collected samples. Furthermore, they were significantly efficient in degrading cellulose, starch, pectin, and lignin. Since the management of crop residues has become an essential aspect of sustaining long-term fertility in cropping systems, incorporation of rice straw, which is rich with cellulose, and the application of Trichoderma species into the harvested rice fields will improve the nutrient availability and hence rice yield.
Phylloremediation of pyrene and anthracene by endophytic fungi inhabiting tea leaves (Camellia sinensis (L.) Kuntze) in Sri Lanka
(Tylor & Francis, 2023) Undugoda, Lanka; Thambugala, Kasun; Kannangara, Sagarika; Munasinghe, Jayantha; Premarathna, Nadeeka; Dharmasiri, Nadeema
Polyaromatic hydrocarbons (PAHs) released from vehicular emissions and oil refineries deposit on the phyllosphere, compromising the quality of leaf-based food products by posing many health issues. Nevertheless, the tea phyllosphere harbours a variety of endophytes that are highly effective at degrading polyaromatic hydrocarbons, anthracene, and pyrene. The present study attempts to analyse the pyrene and anthracene degrading capability of phyllosphere endophytic fungi that inhabit Camellia sinensis (L.) Kuntze leaves. The frequency of occurrence of endophytic fungi in different leaf tissue layers was examined using light and scanning electron microscopy (SEM). The best pyrene and anthracene degrading strains were selected based on the High-Performance Liquid Chromatography (HPLC) results, and further kinetic assays. Light microscopy and SEM observations highlighted a heterogeneous endophytic fungal distribution among leaf tissue layers; the upper epidermis had the highest fungal distribution compared to other leaf layers. HPLC results revealed that Phyllosticta capitalensis, Colletotrichum gloeosporioides, Colletotrichum siamense, Pseudopestalotiopsis chinensis, and Daldinia eschscholtzii, have higher pyrene and anthracene degradation respectively and their PAH degradation kinetics follow the first-order kinetic model. The best anthracene and pyrene degrader, P. capitalensis showed the lowest half-life. The present investigation highlights the potential of P. capitalensis, the best pyrene and anthracene degrader that can remediate PAHs deposited on the phyllosphere of tea leaves.
Revealing the endophytic mycoflora in tea (Camellia sinensis) leaves in Sri Lanka: the first comprehensive study
(Phytotaxa, 2021) Thambugala, Kasun; Daranagama, Sinushani; Kannangara, Sagarika; Kodituwakku, Shenuka
Endophytic fungi are a diverse group of microorganisms that live asymptomatically in healthy tissues of host and they have been reported from all kinds of plant tissues such as leaves, stems, roots, flowers, and fruits. In this study, fungal endophytes associated with tea leaves (Camellia sinensis) were collected from Kandy, Kegalle, and Nuwara Eliya districts in Sri Lanka and were isolated, characterized, and identified. A total of twenty endophytic fungal isolates belonging to five genera were recovered and ITS-rDNA sequence data were used to identify them. All isolated endophytic fungal strains belong to the phylum Ascomycota and the majority of these isolates were identified as Colletotrichum species. Phyllosticta capitalensis was the most commonly found fungal endophyte in tea leaves and was recorded in all three districts where the samples were collected. This is the very first investigation on fungal endophytes associated with C. sinensis in Sri Lanka based on molecular sequence data. In addition, a comprehensive account of known endophytic fungi reported worldwide on Camellia sinensis is provided.