Browsing by Author "Undugoda, L."

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Developing sustainable textiles with cellulosic fibers modified with natural antibacterial agents
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Dissanayake, T. W. M. I. I.; Samarasinghe, S. A. S. C.; Undugoda, L.
In the modern world, fibers with natural origin are gaining popularity because of their widespread availability, biodegradability, and comfortability. Furthermore, natural fibers are a renewable resource with minimal environmental burden. Among the diverse sources available, pineapple (Ananas comosus) leaf fiber (PALF) is a promising textile fiber due to its exceptional tensile strength (highest tensile strength among other known natural fibers), remarkable thermal and acoustic insulation properties, and cost-effectiveness. Extraction of PALF can be achieved both mechanically and manually. The surface of the extracted fibers can be modified by chemical treatments, physicochemical treatments, physical treatments, or thermal treatments. These treatments can improve pineapple leaf fibers' physical, mechanical, and thermal properties. The current work enhanced the antibacterial properties of PALF using clove oil. Clove oil is produced by Syzygium aromaticum. The predominant ingredient in clove extraction is eugenol, which is considered as the primary antibacterial agent. Polyvinyl alcohol (PVA) was initially crosslinked onto the cellulose fibers using Citric acid as the crosslinking agent to make a crosslinking system; the formation of crosslinks, was confirmed by the Fourier Transform Infrared Spectroscopy (FTIR), which resulted in a peak at 1712 cm-1 for the ester bond formation of PVA and cellulose. Subsequently, clove oil was dispersed using Cetrimonium bromide (CTAB) as the surfactant. Antibacterial properties of clove oil-coated pineapple leaf nonwoven fabric were evaluated against Gram-positive and Gram-negative bacteria using the disc diffusion method. Staphylococcus aureus was used as a Gram-positive bacterium, while Klebsiella pneumoniae and Escherichia coli were used as Gram-negative bacteria. Interestingly, the system with optimum anti-bacterial activity showed the highest inhibition diameters for all these bacteria. The highest inhibition diameters for S. aureus, K. pneumoniae, and E. coli were 22 mm, 13 mm, and 9 mm, respectively. This clove oil-coated pineapple leaf nonwoven fabric can be used in medical textile applications such as drapes and cloths, surgical gowns, surgical caps, and health care hygiene products.
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.
Selecting a best fitting mathematical model for fermentation kinetics of spontaneous wine fermentation process
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Madhuhansi, H. A. R.; Munasinghe, J.; Undugoda, L.
Spontaneous wine fermentation involves fermenting “grape must” using indigenous yeasts inhabiting the grapes’ skin. Consistent alcohol level is crucial for producing a final product that meets quality standards in the wine industry. Therefore, this study aims to identify the most suitable mathematical model to characterize the alcohol production dynamics of indigenous yeast during spontaneous wine fermentation, with a specific focus on Sri Lanka’s wine industry. The research highlights the contributions of five major indigenous yeast species: P. kudriavzevii, H. guilliermondii, H. opuntiae, H. uvarum, and S. bacillaris. Grape samples collected from Urumpirai, Jaffna, Sri Lanka, underwent separate fermentation processes with each yeast species, and alcohol levels were measured at regular intervals. All the experimental data sets were statistically analyzed using SPSS (version 23). The box plot analysis revealed that no outliers were detected from an initial set of 120 data points. One-way ANOVA test revealed statistically significant differences in alcohol levels across various time intervals. The kinetic parameters of the wine fermentation process were analyzed using several models, including the logistic model, the Gompertz model, the Richards model, and their respective modified versions. Among them, the modified Gompertz model became the best-fit mathematical model to describe the alcohol production patterns of each yeast species separately. The model’s accuracy was evaluated using several statistical measures, such as the coefficient of determination (R²), adjusted chi-square value, residual sum of squares (RSS), and F-value. The results demonstrated a significant variation in alcohol levels over time for each yeast species, highlighting their distinct fermentation profiles. Key parameters of the modified Gompertz model, maximum alcohol production rate (%𝑣/𝑣 ℎ-1), lag period (ℎ), and upper asymptote for product formation (%𝑣/𝑣) were estimated numerically by using the Originlab (2024) software, for each yeast species and, their alcohol production abilities were studied separately. These findings pave the way for industrial scale quality wine production using the concept of spontaneous fermentation.
Selection of best fitting mathematical model to analyse the anthracene degradation ability of Bacillus velezensis
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Madushika, S. A. R. R.; Munasinghe, J.; Undugoda, L.
Living things frequently come into contact with a wide range of harmful pollutants, including polyaromatic hydrocarbons (PAHs) like anthracene, which are highly carcinogenic and genotoxic. Microbial degradation is the most promising approach for removing anthracene from the environment, using microorganisms to transform it into nontoxic compounds, rather than using physical and chemical methods. The study aimed to assess the kinetic approach in anthracene degradation by Bacillus velezensis, isolated from the phyllosphere of leaf samples. Leaf samples (Ixora chinensis, Ervatamia divaricate, and Plumeria sp.) were collected by using random sampling techniques from the most polluted urban areas (Maradana, Orugodawatta, Pettah, Panchikawatta, Sapugaskanda, and Colombo Fort) in Sri Lanka. Then, in vitro, anthracene degradation patterns were analysed using HPLC analysis at different anthracene concentrations (100 ppm, 200 ppm, 300ppm, 400 ppm, 500 ppm, and 600 ppm) as a model of limited substrates while monitoring the growth patterns based on fluctuations in dry cell biomass. Anthracene was completely degraded in six days of incubation for low initial anthracene concentrations. Dry cell biomass and degradation percentages were measured with time for different initial liquid substrate concentrations of PAHs. The specific growth rates and degradation rates were calculated. The study used box plot analysis to identify and eliminate outliers from 65 data points, ensuring the validity and reliability of the findings. After eliminating four outliers, 61 usable data points were obtained, and the ANOVA was used to compare average specific growth rates between anthracene concentration groups, revealing all specific growth rates were statistically significant. The kinetic parameters of anthracene degradation were analysed by using various models including, Monod's, Haldane’s, Wayman and Tseng's models because they focused on their convergence with experimental data. The models were evaluated by determining the parameter’s significant value, Root Mean Square Error (RMSE), and the Adj.R2 value. Among these models, Wayman and Tseng's model demonstrated the better fit for the experiment with Adj.R2 - 0.95191 and RMSE – 0.0019. The experimental kinetics data of anthracene degradation closely followed Wayman and Tseng’s model, indicating that this model provided an accurate representation of the interaction between the PAH substrate (anthracene) and the growth kinetics of the microorganisms. The half saturation constant Ks, the maximum specific growth rate “max, the threshold substrate concentration “, and the inhibition coefficient i were defined as Wayman and Tseng’s model parameters and were estimated in their numerical values.
Suppression and management of Meloidogyne incognita in soil using Trichoderma harzianum NFCF160 and Trichoderma virens Isf-77
(Malaysian Journal of Microbiology, 2022) Rajakaruna, N.; Undugoda, L.; Kannangara, S.; Abeywickrama, K.
Aims: Meloidogyne incognita adversely affects numerous crop plants worldwide. Therefore, the modern world has been moving towards biocontrol methods to prevent nematode attacks. This study was aimed to (i) investigate the potential use of Trichoderma harzianum NFCF160 and T. virens Isf-77 in managing M. incognita in soil and (ii) identify trapping mechanisms employed by both Trichoderma strains to suppress M. incognita. Methodology and results: Three weeks old, Basella alba L. plants were subjected to five different treatments. The above and below ground growth parameters and the galling indices of these plants were measured every four weeks for three sampling times. Trapping mechanisms employed by Trichoderma strains were examined following plate assays. Plants treated with T. harzianum NFCF160 and T. virens Isf-77 had significantly higher values for the total number of leaves (34 ± 2.84) and (27 ± 2.61), fresh weight of the shoot (81 ± 9.51 g) and (91 ± 9.70 g), dry weight of the shoot (71 ± 5.24 g) and (62 ± 5.81 g), respectively eight weeks after inoculation of M. incognita. Significantly low galling indices (2 and 2) were recorded in B. alba treated with Trichoderma strains. Both Trichoderma strains exhibited various nematode-trapping mechanisms, such as non-constricting rings and adhesive spores. Conclusion, significance and impact of study: This investigation highlighted the potential of both Trichoderma strains as biocontrol agents to control M. incognita effect in sustainable agriculture.