Browsing by Author "Udayanga, D."

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    PublicationOpen Access
    Characterisation of Acid Protease-Producing Bacterium Micrococcus luteus from the Pitcher Fluid of Nepenthes distillatoria L.
    (Department of Applied Sciences. Faculty of Humanities and Sciences,SLIIT, 2025-10-10) Gunawardhana, P.; Manamgoda, D.; Udayanga, D.
    Nepenthes distillatoria L., a carnivorous plant endemic to Sri Lanka, produces pitcher fluid, rich in digestive enzymes. Despite its apparently hostile conditions, the pitcher fluid harbours a diverse and unique microbial community. In this study, bacteria were isolated from the open pitcher fluid of N. distillatoria collected at two sites in distinct locations in Kalawana, Rathnapura district, in Sri Lanka. From twelve samples, twenty-four bacterial isolates were obtained and subjected to acid-protease enzyme assay using an agar plate method. Relative enzymatic activity was quantified for all the isolates that produced positive results. Notably, one isolate displaying significant acid protease activity was identified as Micrococcus luteus based on 16S rRNA sequence analysis. Therefore, this study revealed the pitcher fluid of N. distillatoria supports a distinct bacterial community with potential industrial applications, highlighting its value as a promising source for bioprospecting.
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    PublicationOpen Access
    Impact of geographical variation on proximate composition of Sesbania grandiflora L. in Sri Lanka
    (Department of Applied Sciences. Faculty of Humanities and Sciences,SLIIT, 2025-10-10) Dahanayaka, L. W.; Mapa, M. S. T.; Kadigamuwa,C. C.; Udayanga, D.
    Sesbania grandiflora L. is a widely consumed green leafy vegetable in Sri Lanka, valued for its nutritional and therapeutic benefits. The nutrient composition can vary depending on many factors, including the geographical location. This study investigated the variation in proximate composition of S. grandiflora L. leaves collected from 16 locations across diverse agro-climatic zones in Sri Lanka, focusing on moisture,ash, protein, fat, carbohydrate, and fibre content. Samples were collected, cultivated under organic farming practices, and analysed using standard AOAC methods, methods of analysis established by the AOAC International (formerly the Association of Official Analytical Chemists). One-way ANOVA followed by Tukey post hoc test revealed significant differences (p < 0.05) in nutrient composition among the locations. Moisture content ranged from 64.13% to 82.79%, with both extremes recorded within the low-country wet zone, indicating substantial micro-environmental influence. Ash content varied from 1.89% to 5.68%, reflecting differences in mineral availability across soils. The highest protein content was recorded in the low-country dry zone (16.38%). Carbohydrate and fibre content were notably high in the low-country wet zone, with values reaching 18.33% and 11.79%, respectively. The findings highlight the influence of geographical location on the nutritional quality of S. grandiflora L. This study provides valuable insights for optimising the cultivation of S. grandiflora, contributing to improved dietary planning and region-specific agricultural practices in Sri Lanka.
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    PublicationOpen Access
    Molecular and Morphological Identification of Ustilaginoidea Virens, the Causal Agent of Rice False Smut in Sri Lanka
    (Department of Applied Sciences. Faculty of Humanities and Sciences,SLIIT, 2025-10-10) Sewwandi, E. D. S.; Manamgoda, D. S.; Udayanga, D.
    Seed-borne fungal pathogens significantly impact on both the quality and quantity of rice production of rice. Among these, Ustilaginoidea virens, the causal agent of rice false smut, directly impacts grain yield and quality by partially or completely replacing kernels with spore masses. Historically considered a minor issue, false smut has recently emerged as a major rice disease of concern. Accurate identification andconfirmation of U. virens are thus critical for developing effective disease management strategies. In this study, rice panicles with characteristic false smut symptoms were collected from the wet zone of Sri Lanka. The associated fungal pathogen was isolated on potato sucrose agar (PSA) and designated as isolateWC2.04. Colony and micro-morphological features of the isolate obtained were documented, followed by DNA extraction, Polymerase chain reaction and bidirectional Sanger sequencing of the internal transcribed spacer (ITS) region. Sequence data were analyzed using the Basic Local Alignment Search Tool (BLAST) against the NCBI database, and phylogenetic analyses were performed. The results confirmed the identity of WC2.04 as U. virens. This study presents the first molecular confirmation of the occurrence of U. virens in Sri Lanka, highlighting the importance of integrating morphological and molecular approaches for the accurate identification of rice seed-borne fungi. Accurate identification is crucial for developing and implementing effective disease management strategies to mitigate the impact of rice false smut in the region.