Faculty of Humanities and Sciences
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Publication Open Access Biochemical shifts in Chlorella vulgaris via post-stationary magnesium sulfate stress: optimizing biomass for advanced bio-fertilizers(Frontiers Media SA, 2026-06-09) Dodangodage, C. A; Kasturiarachchi, J. C; Perera, T.A; Rajapakshe, S.D; Niyangoda, S.S; Halwatura, R.USustainable agriculture requires bio-fertilizers that improve both nutrient efficiency and soil resilience. Microalgae are promising candidates; however, conventional optimization using sodium chloride (NaCl) stress introduces phytotoxic sodium residues that limit soil application. To address this, a biphasic cultivation strategy for Chlorella vulgaris was developed using magnesium sulfate (MgSO4) as a dual-function stressor. Following the onset of a nitrogen-limited stationary phase (Day 18), the addition of 0.4 g L-¹ MgSO4 induced intracellular macromolecular accumulation. Biomass increased by 44.8% (2.810 ± 0.090 g L-¹), driven by intracellular densification, with enrichment in both total carbohydrate (42.15 ± 2.10%) and lipid (36.24 ± 1.11%) fractions. Substituting NaCl with MgSO4 eliminates the risk of sodium-induced phytotoxicity upon soil application, while simultaneously pre-loading the biomass with essential secondary macronutrients. Overall, this study demonstrates that targeted MgSO4-induced metabolic shifts can generate high-density, functionally enhanced, sodium-free microalgal biomass to serve as a potential bio-fertilizer feedstock.Publication Open Access Novel mycelium-based composites with enhanced physico-mechanical properties, as sustainable alternatives for packaging applications(Taylor and Francis Ltd., 2026-07-17) Madusanka, C; Udayanga, D; Nilmini, R; Rajapaksha, S; Hewawasam, C; Manamgoda, D; Herath, I. SMycelium-based composites (MBCs) are produced through a combination of fungi and lignocellulosic materials. Identifying novel combinations of fungi and lignocellulosic waste is crucial for exploring new material properties. In this study, MBCs were prepared with strains of Ganoderma orbiforme and Lentinus squarrosulus from Sri Lanka, using three different types of locally sourced lignocellulosic substrates, including Cocos nucifera sawdust, Mangifera indica sawdust, and coir pith derived from coconut husk. Mycelium inoculum grown on rice seeds was introduced to organic substrates and incubated at 28 °C for 30 d. The resulting composites were separated from the container, dried at 80 °C, and characterised for physicochemical, and microscopic properties. Results indicated that the produced MBCs exhibit properties equivalent to or superior to those of expanded polystyrene (EPS). The Ashby chart generated revealed that MBCs possess properties comparable to cork and other low-density foams, making them suitable for insulating, cushioning, and packaging applications. Among the combinations tested, MBCs made with coir pith and coconut sawdust proved to be the most effective, eco-friendly alternatives to protective packaging.Publication Open Access Coordinated lignocellulolysis: topological analysis reveals coordinated lignocellulolysis in Klebsiella–Enterobacter-mediated rice straw degradation via surface delignification and cellulose crystallinity modulation(Microbiology Society, 2026-05-12) Senadheera, U. E; Jayasanka, D.J; Hewawasam, C; Udayanga, D; Takimoto, Y; Tadachika, NSurface-sterilized Oryza sativa AT362 straw was screened for endophytic ligninolytic and cellulolytic bacteria using colour unit reduction and Congo Red decolorization assays. Ligninolytic Klebsiella variicola AKL1104 and cellulolytic Enterobacter chuandaensis AKC1108, biocompatible, were inoculated at a 1:1 ratio and incubated in 1% (w/v) rice straw broth at 37 °C for 7 days. Topological changes due to degradation were conducted using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) for 9 days. During t=9 d, SEM shows vascular tissue perforation with tunnels, indicating K. variicola mediated-delignification, allowing E. chuandaensis to sequentially degrade cellulose. XRD revealed a cellulose crystallinity decline from 30.08% on t=0 d to 11.76% on t=9 d. Electron microscopy and crystallite size calculations in t=6 d (6.81 nm) and t=9 d (90.16 nm) indicate self-assembly of cellulose fibrils. FTIR and XPS analysis indicated crystalline cellulose transformation to amorphous cellulose as the lateral order index dropped from 0.776±0.006 to 0.503±0.007, while surface lignin coverage was reduced from 5.01 to 2.20%, respectively.Publication Open Access A novel solid-state, multi-layered biodegradable microbial inoculant system for rice straw composting: biocapsule design, characterization, and performance evaluation(Frontiers Media SA, 2026-04-17) Senadheera, U. E; Jasintha Jayasanka, D; Hewawasam, C; Udayanga, D; Takimoto, Y; Nakayama, TLignocellulolytic microbial inoculants are widely used to enhance lignocellulosic waste composting, but their efficacy is often limited by environmental stress and uncontrolled release when conventional liquid inoculants are used. This study introduces a multi-layered biocapsule structure that sustains lignocellulolytic microbial activity and evaluates its composting efficiency through control experiments. A three-layered biodegradable biocapsule was designed using a rice straw biocomposite, humic acid, activated carbon, corn starch, carboxymethyl cellulose, and calcium alginate beads with encapsulated Klebsiella–Enterobacter consortium immobilized on hydroxyapatite nanoparticles. The biocapsule comprises a rice straw outer biocomposite shell in the outermost layer, a moisture retention hydrogel in the middle, and the encapsulated bacteria in calcium alginate beads in the core. The designed biocapsule was used in three treatments: intact biocapsule, powdered biocapsule, and a control (without inoculants), and the composting efficacy was evaluated against Sri Lankan Standards for compost products. Calcium alginate beads achieved 78.29% ± 9.57% and 84.45% ± 6.04% bacterial encapsulation efficiency and bacterial release, respectively, with heavy bacterial colonization in beads. The entire biocapsule reached 56.16% ± 1.65% biodegradation in 7 days. Intact biocapsule enhanced early lignocellulolysis, faster pH neutralization, and reduced electrical conductivity to 0.62 ± 0.00 while sustaining prolonged thermogenesis above 55 °C for 25 days. The intact biocapsule significantly improved compost nutrient availability, increasing total nitrogen, phosphorus, and potassium levels by 71.89%, 83.0%, and 60.66%, respectively, while achieving a total organic carbon loss of 53.30% and a Carbon: Nitrogen ratio decline of 72.83%.Publication Open Access Synergistic Bioactive Ointment: ZnO Nanoparticles Combined with Carica papaya Latex and Aloe Vera Gel for Broad-Spectrum Biomedical Applications(PloS one, 2026-07-21) Ekanayake, G; Mendis, A; Wijayawardana, S; Thambiliyagodage, C; Jayanetti, MThe development of multifunctional topical formulations that combine natural bioactives with therapeutic nanomaterials offers a promising route to improved wound healing and management. Carica papaya fruit latex powder and Aloe barbadensis Miller gel were incorporated as active ingredients into an ointment base consisting of ZnO nanoparticles, cassava starch, and white petroleum jelly to formulate a novel topical medication with enhanced biological properties. According to the 2,2-diphenyl-1-picrylhydrazyl antioxidant assay, IC50 values of Carica papaya latex, Aloe gel, and ZnO nanoparticles were 454.54, 312.50, and 490.82 μg/mL, respectively. Carica papaya latex powder showed a protease activity of 58.40 units/mg of the solid. The ointment base exhibited the lowest blood clotting index (3.57 ± 6.09%), suggesting strong coagulation potential, whereas ZnO showed the highest (22.26 ± 1.09%), indicating minimal clotting ability under the current experimental setup. Erythrocyte adsorption was also highest in the ointment base (84.10 ± 1.09%), reinforcing its strong interaction with blood components. Cassava starch and petroleum jelly displayed moderate Red Blood Cell (RBC) attachment percentages. Platelet adhesion with the ointment base (61.55 ± 1.09%) and cassava starch (53.97 ± 2.40%) showed better platelet interaction than ZnO (29.1 ± 4.08%). Hemolysis data indicated that petroleum jelly caused the highest RBC lysis at all concentrations, while the ointment base showed the lowest activity, indicating better hemocompatibility. Clotting time analysis further highlighted the ointment base and petroleum jelly as effective pro-coagulants (13.30 s and 13.34 s, respectively), whereas ZnO (18.34 min) and cassava starch (48.34 s) exhibited delayed clotting. The ointment in which the base: active ingredient ratio is 7:3, and within, Carica papaya latex: Aloe gel ratio 1:4, shows the maximum antibacterial activity against Staphylococcus aureus and Escherichia coli. The MBC/MIC ratios of the above ointment for the two organisms were lower than 4, suggesting a bactericidal effect. The time-kill curves show a gradual reduction in bacterial survival over time, with the most significant reduction observed in the ointment with the highest proportion of Aloe vera.Publication Open Access Copper-Based Nanoparticles as Precision Nanoantibiotics against Bacterial Blight in Anthurium andraeanum Lind.: Synthesis, Characterization, and Antibacterial Efficacy under In Vitro and In Vivo Conditions(American Chemical Society, 2026-05-05) Wanaguru, S; Jayasinghe, S; Seneviratne, K; Kottegoda, N; Peiris, Sriyani E; Peiris, Colin NThe bacterial blight disease caused by Xanthomonas spp., a dilemma for farmers worldwide. The existing conventional methods have failed to effectively combat the disease. Therefore, it is crucial to focus on developing and implementing more affordable techniques to effectively manage bacterial blight effectively. Herein, we investigated the efficacy of copper-based nanoparticles (Cu NPs) synthesized via three different methods toward controlling bacterial blight disease in Anthurium andraeanum plants. For that, Cu NPs were engineered via chemical, semichemical, and green synthesis approaches. Cu NPs were characterized through scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier-transform infrared (FTIR), and powder X-ray diffraction (PXRD) analysis. Quantitative antibacterial assays revealed that the chemical and green-synthesized Cu NPs exhibited the highest potency, with a minimum inhibitory concentration (MIC) of 31.25 μg/mL and a minimum bactericidal concentration (MBC) of 62.50 μg/mL, whereas the semichemical formulation showed lower activity (MIC = 62.50 μg/mL; MBC = 125 μg/mL). In vitro well-diffusion assays further supported this trend: at 30 ppm, the inhibition zones measured 25 ± 0.81, 15 ± 0.81, and 20.6 ± 0.94 mm for the chemical, semichemical, and green synthesis methods, respectively, compared to 26.3 ± 0.47 mm for the positive control-antibiotic sulfamethoxazole. At in vivo, optimized concentration of 200 ppm, Cu NPs produced via all three methods controlled bacterial blight disease in 90% of treated anthurium plants within 4, 7, and 5 weeks, respectively, without causing phytotoxicity. Disease progression was monitored over 12 weeks by measuring lesion areas, and statistical significance of treatments was determined using two-way analysis of variance (ANOVA). ©Publication Open Access Valorization of acid-hydrolyzed tea stem waste for sustainable biodiesel production using Chlorella vulgaris: a biorefinery approach(Frontiers Media SA, 2026-05-18) Dodangodage, C. A; Rathnapriya R.H.N.S.; Gamage, G. N; Kasturiarachchi, Jagath C.; Perera, Thilini A.; Rajapakshe, S. D; Niyangoda, Sayuri S.; Halwatura, R.UThe prohibitive cost of synthetic cultivation media remains a fundamental bottleneck in the commercial deployment of microalgal biodiesel. This study investigates the valorization of recalcitrant tea stem waste, an abundant agro-industrial by-product, as a low-cost, nutrient-rich medium for Chlorella vulgaris within an integrated biorefinery framework. Following thermochemical acid hydrolysis, a two-stage optimization of hydrolysate concentration and incident irradiance was conducted to maximize biomass production. Undiluted (100%) hydrolysate under elevated irradiance (240 µmol photons m-2 s-1) compensated for optical attenuation in the dark medium and yielded a maximum biomass concentration of 1.65 ± 0.07 g L-1, representing an approximately 5-fold increase over the synthetic Bold’s Basal Medium (BBM) control. Concurrently, substantial nutrient recovery was achieved, with 83.23% nitrate and 95.60% phosphate assimilation by Day 10. The resulting nutrient limitation acted as a secondary abiotic stressor, triggering enhanced intracellular lipid accumulation and yielding a peak volumetric lipid concentration of 0.094 ± 0.005 g L-1, approximately 4.5-fold higher than the autotrophic control. Fatty acid methyl ester (FAME) profiling revealed a saturated-dominant composition (85.57% SFA), corresponding to favorable predicted biodiesel properties, including low iodine value and high cetane number, consistent with international fuel standards. Overall, this study establishes tea stem hydrolysate as an efficient integrated cultivation matrix for simultaneous mixotrophic growth and lipid biosynthesis, advancing a scalable circular waste-to-energy pathway for agro-industrial systems.Publication Open Access Chitosan-Starch Biocomposite for Enhanced Curcumin Delivery: Kinetic Modeling of pH and Ionic Strength Responsive Release and Evaluation of Biological Efficacy(American Chemical Society, 2026-07-21) Abeywickrama, L; Wijayawardana, S; Thambiliyagodage, C; Jayanetti, MadaraA drug delivery system composed of chitosan and starch was used to deliver curcumin effectively by enhancing its pharmacokinetic properties. The sustained release of the synthesized delivery system was evaluated using a kinetic modeling approach along with its biological efficacy. The SEM analysis confirmed the coupling of starch and chitosan and loading of curcumin into the matrix during synthesis. Crystallographic orientation of the delivery system was confirmed by XRD, and the FT-IR data confirmed the successful loading of curcumin. TG analysis indicated that the increment in decomposition temperature of the composite is due to the incorporation of curcumin into the composite. BET analysis revealed the reduction in the BET surface area and pore volume in the synthesized composite, confirming successful loading. The IC50 values of the curcumin and composite for the DPPH assay were 17.81 μg/mL and 38.77 μg/mL, respectively. Composite material has shown enhanced antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa at 20 mg/mL, with inhibition zones of 15.56 ± 0.29 and 10.11 ± 0.44 mm, respectively. Allium cepa cytotoxicity assay confirmed that all the synthesized materials promote mitosis at 2.5 mg/mL concentration. The pH and ionic strength responsive release of curcumin was studied by fitting the release data into six kinetic models, including Korsemeyer–Peppas (KP) and Peppas–Sahlin (PS), which has not been reported earlier for the synthesized system. The KP and PS models were selected to interpret the release mechanism based on R2. A combination of Fickian diffusion, relaxation and swelling dominates the curcumin release. According to the KP model, quasi-Fickian diffusion is responsible for the release in acidic and alkaline pH, whereas non-Fickian diffusion occurs at pH 6.7. At higher [NaCl], relaxation is responsible for the release (n > 0.43, kD = 0), while a combination of diffusion and relaxation governs the release at lower [NaCl]. These behaviors are related to the chemical composition of chitosan and the release media, where the electrostatic repulsion, protonation and charge screening contribute to curcumin release.Publication Open Access Valorization of Canteen Wastewater Through Optimized Spirulina Platensis Cultivation for Enhanced Carotenoid Production and Nutrient Removal(Multidisciplinary Digital Publishing Institute (MDPI), 2026-01-14) Dodangodage, C. A; Gamage, G.N; Wijesekara, I.A; Kasturiarachchi, J.C; Perera, T.A; Rajapakshe, D; Halwatura, R.UThe valorization of nutrient-rich institutional effluents represents a promising route for sustainable algal biotechnology. This study investigates the potential of canteen wastewater (CW) as an alternative culture medium for Spirulina platensis, integrating wastewater treatment with high-value carotenoid and lipid production. Growth performance, biochemical composition, and nutrient removal efficiencies were systematically evaluated in 2 L photobioreactors under optimized conditions. Spirulina cultured in 75% CW under 180 μmol photons m−2 s−1 achieved a biomass productivity of 0.071 g L−1 day−1, nearly three-fold higher than the synthetic BG-11 control (0.023 g L−1 day−1). Nutrient remediation was highly efficient, with 92.12% nitrate and 90.05% phosphate removal, effectively reducing effluent concentrations below discharge limits. Biochemical profiling revealed that wastewater-grown biomass contained 54.3% protein and 7.85% lipids, with a remarkable carotenoid yield of 21.81 mg g−1 DW—significantly higher than the control (6.85 mg g−1 DW). Mechanistic analysis suggests that the balanced nutrient stoichiometry (C:N:P ≈ 30:4:1) and mixotrophic conditions enhanced biomass quality while mitigating ammonia toxicity. This study demonstrates the first integrated application of canteen wastewater for dual-purpose bioremediation and pigment-rich biomass production, establishing a scalable circular bioeconomy framework for institutional waste management.Publication Open Access Production of Carbohydrate-Rich Chlorella sp. Biomass Using Clarified Aquaponics Effluent for Bioethanol Feedstock Applications(Multidisciplinary Digital Publishing Institute (MDPI), 2026-03-26) Dodangodage, C. A; Gamage, G. N; Mallawa, L.C; Kasturiarachchi, J.C; Fernando, K. V; Halwatura, R.H; Perera, T.A; Rajapakshe, S.D; Niyangoda, S.S; Halwatura, R.UThe integration of microalgal cultivation with wastewater streams offers a promising pathway to enhance resource efficiency within circular bioeconomy frameworks. However, the suitability of clarified aquaponics sedimentation effluent for producing carbohydrate-rich microalgal biomass remains insufficiently evaluated, particularly with respect to nutrient recovery and bioethanol-relevant feedstock potential. In this study, clarified aquaponics sedimentation effluent was assessed as a cultivation medium for Chlorella sp. under controlled laboratory conditions. Biomass productivity, nutrient removal performance, and carbohydrate accumulation were systematically evaluated and compared with conventional synthetic medium. Chlorella sp. cultivated in clarified aquaponic effluent achieved a maximum biomass concentration of approximately 2.05 g L−1, exceeding that obtained in Bold’s Basal Medium. Carbohydrate content exceeded 40% of dry weight, indicating suitability for fermentable sugar production. Nitrate and phosphate removal efficiencies greater than 95% were achieved, with mass balance analysis confirming biological assimilation as the primary removal mechanism (~87.4%). This confirms the dual functionality of the system. The effective nutrient assimilation and confirmed the dual functionality of the system as both a biomass production and nutrient recovery process. Comparable performance under diluted and undiluted effluent conditions further indicated that freshwater dilution is not required following clarification. Light saturation was observed at 180–190 μmol m−2 s−1, providing guidance for energy-efficient operation. These findings demonstrate that clarified aquaponics effluent can serve as an effective alternative growth medium for producing carbohydrate-rich Chlorella sp. biomass while enabling nutrient recovery. The estimated bioethanol potential is theoretical, based on stoichiometric conversion assumptions, and experimental fermentation was not conducted. This work provides quantitative evidence supporting the integration of microalgae into aquaponic systems and establishes a foundation for future pilot-scale, techno-economic, and life-cycle assessments.