University of Sri Jayewardenepura: Journals & Proceedings

Environmental Engineering and Green Technology Proceedings of the 28th International Forestry and Environment Symposium 2024 of the Department of Forestry and Environmental Science, University of Sri Jayewardenepura, Sri Lanka   150 (ID 036)  Hydrothermal Synthesis of Antimicrobial Carbon Dots from the Soot of  Three Different Essential Oils  Fernandez, A.B.1,2*, Buddhinie, P.K. C.1, Vithanage, M.2  1Department of Botany, University of Sri Jayewardenepura, Nugegoda, Sri Lanka 2Ecosphere Resilience Research Centre, University of Sri Jayewardenepura, Nugegoda, Sri Lanka  *breverlyfernandez@gmail.com  Abstract  Carbon dots (CDs) have garnered the interest and demand of researchers over the years, and they are also favoured as a novel and better alternative to conventional antibiotics and other antimicrobial agents. While the antimicrobial properties of CDs differ with the precursors used, a synergistic effect is expected to arise from the use of antimicrobial compounds as precursors in the synthesis of CDs. Therefore, in this study, a novel green method was introduced for the hydrothermal synthesis of carbon dots using the soot of three essential oils (EOs) as the carbon source; clove (Syzygium aromaticum), cinnamon (Cinnamomum zeylanicum) and citrus (Citrus aurantifolia); in the absence of surface passivating agents. Here, the three essential oils were burned and the carbon soot from each oil was collected separately. Then the carbon soot was subjected to hydrothermal treatment by heating at 160° C for 3 hours without any doping or modification. The obtained carbon dots were characterized by Scanning Electron Microscopy (SEM), UV-Vis spectroscopy, FT-IR spectroscopy and Fluorescence analysis. The SEM images of the three types of essential oil-derived CDs were crucial for determining the size, shape, and surface morphology of the prepared CDs. While clove CDs and cinnamon CDs were mostly spherical in shape, citrus CDs exhibited irregular shapes, which could be attributed to the agglomeration of the particles as evident from the SEM images. The results showed that the average particle diameter of the CDs was found to be 56.50±7.75 nm, 56.11±8.11 nm, and 61.67±10.21 nm, for clove CDs, cinnamon CDs and citrus CDs, respectively. UV-Vis spectroscopy analysis further confirmed the formation of CDs as absorption peaks at wavelengths of 205 nm, 215 nm and 244 nm were obtained for citrus, cinnamon and clove CDs respectively. These peaks could be attributed to the π→π* transition of C=C bonds of sp2 carbons. FT-IR spectroscopy was carried out to determine the functional groups in the prepared CDs, as functional groups are responsible for the antimicrobial properties of CDs. In addition to these, the fluorescence analysis confirmed the synthesis of CDs, as CDs are known to be fluorescent. The antibacterial properties of the synthesized CDs were then investigated against Pectobacterium sp. isolated and characterized from the soft rot of carrot.  Keywords: Carbon dots, Essential oils, Hydrothermal synthesis, Antimicrobial, Aggregation   

English

Biodiversity Conservation and Management Proceedings of the 28th International Forestry and Environment Symposium 2024 of the Department of Forestry and Environmental Science, University of Sri Jayewardenepura, Sri Lanka   38 (ID 096)  Distribution Patterns of Impatiens in Sri Lanka: Exploring Niche Breadth, Range Size, and Elevational Dynamics  Ruwanmalie, W.A.P.U.1, Piumal, R.J.1, Viduranga, W.A.A.D.M.2, Kathriarachchi, H.S.1*  1Department of Plant Sciences, University of Colombo, Colombo 03, Sri Lanka 2Department of Ecology and Conservation Biology, Texas A and M University, USA *hashi@pts.cmb.ac.lk  Abstract  In Sri Lanka, Impatiens (Family Balsaminaceae) is represented by 23 native species, of which 16 are endemic. Additionally, 3 exotic Impatiens are widely cultivated as ornamentals. According to the National Red List 2020, of the native species, 6 are vulnerable (VU), 9 are endangered (EN), 2 are critically endangered (CR) and I. walkeri is listed as critically endangered possibly extinct CR(PE). The present study aimed to analyse the current distribution of Impatiens species across floristic regions and along an elevational gradient in Sri Lanka. Species occurrence data were obtained from reputable repositories such as the National Herbarium, international herbaria, various national and international floristic databases. A georeferenced map was meticulously constructed to evaluate the spatial distribution of these species across distinct floristic zones and along an elevation gradient using ArcGIS Pro and R 4.2.2 version. Heat map analysis and Jaccard clustering based on the distribution of species in different floristic zones were used to detect niche specialty. The central mountains, encompassing the Ramboda-Nuwara Eliya and Adam's Peak floristic zones, exhibited the highest species richness of Sri Lankan Impatiens. Jaccard analysis delineated three primary clusters, none of which included the point endemic species, I. janthina and I. jacobdevlasii. Notably, regression analysis revealed a strong correlation (R2=+0.7751) between niche breadth and range size, emphasizing the significance of colonizing adaptability in Impatiens species' occupancy patterns. Impatiens acaulis recorded the broadest niche breadth and the largest range size among the species. The optimal elevation range for the majority of Impatiens species was found to be between 1000 and 1200 meters above. Impatiens acaulis and Impatiens cornigera showed distribution patterns that were largely independent of elevation variations. In contrast, I. macrophylla and I. leptopoda exhibited a limited distribution preference especially for highland regions. The findings of the study are expected to be incorporated to conservation attempts of Impatiens species in Sri Lanka.  Keywords: Impatiens, Elevation, Niche, Range, Sri Lanka   

Forest and Natural Resource Management  Proceedings of the 28th International Forestry and Environment Symposium 2024 of the Department of Forestry and Environmental Science, University of Sri Jayewardenepura, Sri Lanka   28 (ID 038)  Industrial Perspective of Thermo-Stable Proteinase Enzyme Producing Bacteria Isolated from Maha Oya Hot Spring, Sri Lanka  Sadeepa, H.D.D.1,2, Sirisena, S.A.3, Manage, P.M.1*  1Centre for Water Quality and Algae Research, Department of Zoology, University of  Sri Jayewardenepura, Nugegoda, Sri Lanka 2Faculty of Graduate Studies, University of Sri Jayewardenepura, Nugegoda, Sri Lanka 3Department of Environmental Technology, Faculty of Technology, University of Colombo, Colombo 03, Sri Lanka *pathmalal@sjp.ac.lk  Abstract  The microbial enzymes are eco-friendly and cost-effective alternatives for chemical catalysts that adversely affect the ecosystem. Among the commercially available enzymes, proteases are the most demanded enzyme and contributes nearly 60-65 % of the world enzyme market. Therefore, this study aimed on isolation and characterization of thermo-stable proteinase producing hot spring bacteria. For the present study, water samples were collected from surface and bottom of Maha Oya hot springs. Temperature, Electrical Conductivity (EC), pH, and Dissolved Oxygen (DO) were measured at the site. The standard pour plate method was performed to isolate bacteria and primarily screened for proteinase production by Skimmed Milk Agar (SMA) plate assay. Secondary screening was performed using the Folin-Ciocalteu’s Phenol reagent method. Optimum temperatures and pH for enzyme activity were measured for crude enzyme extracts of most potential candidates. Molecular-level identification of bacterial isolates was performed using the 16S rRNA gene sequencing method. Briefly, genomic DNA was extracted from pure bacterial isolates and PCR amplification of V3 and V4 regions of 16S rRNA gene was done using 27F and 1492R bacterial domain specific primers. Then, the DNA sequencing was done at Macrogen, Korea. The resulted sequences were aligned with available sequences at NCBI using BLASTn tool and GenBank accession numbers were obtained. Temperature, EC, pH, and DO of the surface and bottom of the springs varied from 51.7-52.4º C, 1487-1,507 µS/cm, 8.05-8.07, and 2.01-2.05 mg/L respectively. Three morphologically different, proteinase producing bacterial isolates were observed (Mh11, Mh12 and Mh27) at the primary screenings and bacterial isolate: Mh11 which was identified as Bacillus cereus strain VBE03 (Accession number: ON819722) showed the highest enzyme activity of 209.205 U/mL at optimum temperature of 60º C, and optimum pH of 9. Hence, the bacterial isolate: Mh11 would be successfully used for industrial settings operate at temperatures around 60º C and alkaline conditions.  Keywords: Hot springs, Enzymes, Proteinase, Biotechnology, Thermophiles     

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