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Item Biovalorization of agro-food wastes for the production of melanin pigment via a submerged fermentation process using Aspergillus niger: as a sustainable approach(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Rasna, N. F.; Jayathilake, K. M. P. I.; Manage, P. M.; Idroos, F. S.Biovalorization harnesses biological processes to convert waste materials into value added products, encouraging sustainability and resource efficiency. The current study aims to explore and optimize a sustainable method for the production of melanin pigment through the submerged fermentation (SMF) process by utilizing banana peel waste, affected Sesbania grandiflora leaves and stem wastes, and used tea dust waste using Aspergillus niger. The pH, moisture content, total organic carbon, and total ash contents of collected food wastes were measured using standard methods. Fungal cultures were incubated under the submerged fermentation process, at 25 °C with an agitation speed of 160 rpm for 14 days. Subsequently, the fungal-produced pigment was extracted using 1.0 mol/L KOH and subsequently characterized using physicochemical tests with water, organic solvents, alkaline and acidic solutions, and an oxidizing-reducing agent. Further, the pigment was confirmed based on ultraviolet-visible spectroscopic analysis and Fourier-transform infrared spectroscopic (FTIR) analysis. The extracted pigment was tested for toxicity, antibacterial, and antioxidant properties to the determination of the distinctive characteristics and quality of the extracted pigment, hence enabling their industrial use. The pigment yield from banana, Sesbania, and tea wastes were 597.2 ± 21.5 mg/L, 395.4 ± 39.1 mg/L, and 135 ± 12.9 mg/L, respectively. Compared to the control setup, a significant difference (p < 0.05) was observed between the pigment yields produced by A. niger when utilizing different types of food waste. In the physico-chemical analysis, the blackish brown colour of the pigment served as primary evidence for melanin. The pigment was insoluble in water and organic solvents (acetone, chloroform, ethanol, and sodium acetate), but it was readily soluble in KOH and NaOH, precipitated with HCl, and decolorized with H₂O₂. The UV-Vis spectrum indicated that the pigment possessed a λmax around 213–216 nm. The FTIR spectrum showed broad bands around 3000– 3500 cm⁻¹ (OH), 2924.7 and 1032.6 cm⁻¹ (saturated carbon and C-O), 2830–2930 cm⁻¹ (CH2 and CH3), 1500–1650 cm⁻¹ (aromatic C=C or C=O), 1320 and 1390 cm⁻¹ (C-N), and 1210–1230 cm⁻¹ (C-OH). The extracted pigment exhibited low toxicity to mung beans (4.4–6.7%) compared to the positive control (100% extraction solvent). In the antibacterial activity assay, inhibition zones ranged from 2.1 ± 0.1 to 2.6 ± 0.1 cm for Staphylococcus aureus and 2.1 ± 0.1 to 2.5 ± 0.1 cm for Escherichia coli. The antioxidant assay demonstrated an increase in the percentage of DPPH inhibition with increasing pigment concentration, suggesting the pigment's ability to scavenge free radicals. This study proposes a sustainable approach for the production of fungal-based pigment (melanin) through a submerged fermentation process utilizing agro-food wastes with Aspergillus niger strain, which was not documented in previous studies.Item Development and characterization of biodegradable nanocomposite membrane using chitosan and green ZnO nanoparticles(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Ginige, G. C. C.; Manage, P. M.; Idroos, F. S.In response to the growing demand for sustainable industrial materials, this study focuses on the development and characterization of novel Chitosan/green ZnO nanocomposite membranes. This study aims to create inexpensive, non-toxic, and biodegradable materials using sustainable sources. Chitosan, extracted from shrimp shells, was combined with ZnO nanoparticles synthesized through a green approach utilizing the invasive plant Hydrilla verticillata. Chitosan was extracted from shrimp shells, following a series of processes: demineralization using 4% HCl, deproteinization with 5% NaOH, and deacetylation with 70% NaOH, achieving a 61% yield and a moderate degree of deacetylation (DDA%) of 70.83%. The green synthesis of ZnO nanoparticles was carried out using an aqueous extract of the invasive plant Hydrilla verticillata, resulting in a yield of 67.5%. Four types of membranes were fabricated via a solution-cast method, incorporating varying ZnO nanoparticle content (0.0, 0.2, 0.5, and 0.8 g) into a fixed amount of chitosan (1.0 g). The transparency of the membranes decreased, and their color changed from off-white to light brown with increasing ZnO content. Characterization techniques, including XRD, FTIR, SEM, and EDS, were employed. XRD spectra confirmed the crystalline nature of both pure chitosan and CS/ZnO nanocomposite membranes. The presence of characteristic ZnO peaks indicated successful nanocomposite formation. The average crystalline size of ZnO NPs was calculated as 27.49 nm. FTIR spectra revealed the presence of functional groups in chitosan and confirmed the incorporation of ZnO NPs within the nanocomposite membranes. SEM images showed a random pore structure on the pure chitosan membrane surface, while these pores were masked by ZnO NPs in the nanocomposite membranes. EDS results confirmed the presence of expected elements (C, O, N, and Zn) in the nanocomposite membranes. The study demonstrates that these novel nanocomposite membranes, derived from sustainable materials, hold promise for various industrial applications due to their unique combination of biodegradability, non-toxicity, and potential for tailored properties through variations in ZnO NP content.Item Isolation, characterization, and application of phosphate-solubilizing fungi as a biofertilizer for plant growth promotion(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Jayathilake, K. M. P. I.; Manage, P. M.; Idroos, F. S.Plants require major nutrients such as nitrogen and phosphorus for their optimal growth. Phosphorus is an essential macronutrient, yet its availability in soil is often limited due to its insoluble form. Soil microbes can convert insoluble phosphate into soluble phosphate through various mechanisms. Phosphate-solubilizing fungi (PSF) play a vital role in this process, contributing to the phosphorus requirements of plants. Hence, the present study aimed to isolate, characterize, and utilize PSF as a biofertilizer. The PSF strains were isolated from compost soil in Karadiyana (6°48′ 51.8′′ N, 79° 54′ 17.0′′ E) using Pikovskaya's agar (PVK) medium. The phosphate solubilizing index (PSI) was determined by observing halo zone formation after a 7-day incubation period. Phosphate solubilizing efficiency was assessed using PVK broth supplemented with 0.5% tricalcium phosphate following 7 days of incubation at 160 rpm (28 oC). The isolated fungal strains were introduced to a developed potting medium containing compost, coir dust, and soil in a 1:1:1 ratio. Mung bean (Vigna radiata) was selected as the experimental plant. Plant growth parameters (shoot length, root length, wet weight, and dry weight) were measured to determine the effect of the isolated fungal strains. These parameters were recorded after 30 days. Genotypic identification of the isolated strains was performed using the Internal Transcribed Spacer (ITS) region. The strains were confirmed as Fusarium proliferatum, Aspergillus niger, and Aspergillus flavus. A. niger demonstrated the highest phosphate solubilizing efficiency (296.8 ± 0.2 μg/mL) after 6 days of incubation, with a PSI of 2.15 ± 0.1. Fungi-inoculated pots showed a significant increase in shoot length, root length, wet weight, and dry weight compared to the control (n = 9, p < 0.05). Potting media inoculated with A. niger showed the best results, with the highest root length (11.8 ± 0.5 cm), shoot length (16.7 ± 0.5 cm), wet weight (0.6381 ± 0.03 g), and dry weight (0.1060 ± 0.02 g) was recorded. This study suggests that the potting media containing F. proliferatum, A. niger, and A. flavus exhibited significant roles in phosphate solubilization and plant growth promotion, indicating their potential to be used as an effective biofertilizers.Item Isolation and characterization of nitrogen-fixing bacteria from compost soil and their impact on nitrogen uptake and plant growth(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Jayathilake, K. M. P. I.; Manage, P. M.; Idroos, F. S.Nitrogen-fixing bacteria play a critical role in sustainable agriculture by enhancing soil nitrogen availability, reducing the need for synthetic fertilizers, and promoting plant growth. This study aimed to isolate and characterize nitrogen-fixing bacterial (NFB) strains from compost soil and evaluate their potential to improve nitrogen uptake and plant growth. NFB strains were isolated from compost soil in Karadiyana (6°48′ 51.8′′ N, 79° 54′ 17.0′′ E) using an Ashby medium. The molecular level identification of each isolate was carried out using the 16S rRNA gene region. The production ability of ammonia, nitrate, and nitrite was determined after 7 days of incubation in Ashby broth medium inoculated with each isolated strain. The effect of isolated NFB strains on plant growth was determined using a pot experiment. The isolated nitrogen-fixing bacteria (NFB) strains were introduced to the developed potting media prepared with compost, coir dust, and soil in a 1:1:1 ratio, with mung bean (Vigna radiata) selected as the experimental plant. Control potting media was prepared without the inoculation of NFB strains. Shoot length, root length, wet weight, and dry weight of the grown plants were measured after 30 days of the seed germination period as growth parameters to determine the effect of the isolated NFB strains. The molecular level identification confirmed that the isolated strains were Microbacterium aquimaris (CTD16), Bacillus xiamenensis (MCCC 1A00008), Bacillus aerophilus (XA5-12), Bacillus subtilis (NCIB 3610), Bacillus cereus (CCM 2010), Bacillus subtilis (BHU7), and Bacillus aerius (24K). The highest ammonia (1.6 ± 0.5 mg/L) and nitrate (1.08 ± 0.04 mg/L) production were recorded in Ashby broth media inoculated with B. cereus after 7 days of incubation. Pots inoculated with NFB strains showed a significant increase in measured growth parameters compared to the control (n = 9, p < 0.05). Potting media inoculated with B. cereus strain CCM 2010 showed the best results, with the highest root length (11.3 ± 1.1 cm) and shoot length (17.5 ± 0.5 cm), wet weight (0.6898 ± 0.1 g), and dry weight (0.1015 ± 0.01 g) recorded. The study demonstrated that all isolated Bacillus spp. and Microbacterium aquimaris exhibited significant roles in nitrogen fixation. These findings indicate their potential as effective biofertilizers, contributing to enhanced nitrogen availability and improved plant health.Item Prevalence of antibiotic resistance in surface water, ground water and sediment in the transition zone of the Kelani River basin, Sri Lanka(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Meddage, A. K. M. M. K.; Liyanage, G. Y.; Idroos, F. S.; Manage, P. M.Antibiotics are mainly used to treat and prevent diseases in humans and animals, and they also serve as growth promoters and feed efficiency enhancers in agriculture and animal husbandry. However, antibiotic-resistant bacteria (ARB) have emerged as a result of antibiotic overuse and misuse. The prevalence of ARB becomes more critical, particularly for rivers that fulfil urban drinking water demand. Furthermore, the ARB poses a significant threat to human health by potentially treatments ineffective and leading to the spread of untreatable infections. This study aims to screen the presence of ARB against selected antibiotics such as Ciprofloxacin (CIP), Cefuroxime (CXM), Cloxacillin (CLOX), Amoxicillin (AMX), Co-Amoxiclav (CO-AMX); Tetracycline (TC); Azithromycin (AZT), Erythromycin (ERM); Sulfamethoxazole (SMX) and Gentamycin (GEN) in the transition zone of Kelani River Basin, Sri Lanka. Samples were collected during the first inter-monsoon season in March 2024. Twenty-five water samples (groundwater - 07; surface water - 18) and 12 sediment samples were subjected to determine Total Viable Count (TVC) and ARB using the standard pour plate method at 60 mg/L of antibiotic. The TVC of bacteria ranges between 0.2 × 102 – 4.0 × 102 CFU/mL in collected surface water samples, whereas 0.2 × 102 – 2.2 × 102 CFU/mL, and 0.6 × 102 – 1.2 × 102 CFU/mL for groundwater and sediments, respectively. The resistance bacteria percentage against CXM (16.55%), CLOX (15.82%), AMX (13.98%), AUG (12.90%), SMX (10.46%), GEN (10.22%), ERY (8.76%), AZT (6.60%), CIP (2.68%), and TET (2.19%). According to the obtained results, CXM and CLOX showed the highest resistance, indicating bacterial adaptation in both sediment and water. However, TET and CIP exhibited the lowest resistance rates, suggesting they remain effective options. Moderate resistance was observed for SMX and GEN, highlighting the need for cautious use to prevent further resistance. These findings highlight the notable presence of antibiotic-resistant bacteria in environmental samples. Moreover, the results revealed that a thorough investigation into the presence and spread of antibiotic resistance throughout the Kelani River Basin is urgently required.Item Quality index assessment for compost derived from municipal solid waste using novel bacterial consortia(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Wijerathna, P. A. K. C.; Udayagee, K. P. P.; Idroos, F. S.; Manage, P. M.Composting is one of the integral components of the global circular bio-economy platform. Traditional composting requires a prolonged time, and the inoculation of efficient bacterial consortia is a novel technique to enhance the composting rate. Further, assessing compost quality is crucial because the application of immature compost can cause phyto-toxicity, damage the natural ecological balance and disrupt soil structure. The present study focused on the quality assessment of compost produced by five novel microbial consortia (C1–C5) using indexing methods; Clean Index (CI), Fertilizing Index (FI), Germination Index (GI) and Vigor Index (VI). The experiment was conducted using an organic fraction of Municipal Solid Waste (MSW); composed bins made out of concrete were filled with 90 kg of MSW and 2% of v/w each broth consortia were separately inoculated. The experiment was conducted in an open environment, and all the treatments were triplicated. A control treatment with three replicates was used without the addition of any broth consortia. The bins were closely monitored over 30 days for the composting parameters including the pH, conductivity, bulk density and the compost analysis was done following the standard methods. The FI was determined based on the characterization results of the final compost and the CI was determined based on the analyzed heavy metals Cd, Zn, Cr, Pb and Cu analysis carried out using the ICP-OES technique following the acid digestion. The GI and VI were determined using healthy and mature green gram (Vigna radiate) seeds and data were statistically analyzed using Tukey’s test. The FI and CI were calculated using a weighting scale of heavy metals based on their toxicity and the GI and VI were calculated based on the seed germination and their radical lengths. Based on the results, the FI, CI, GI and VI values were significantly different (p < 0.05) and ranged from 3.0–4.5 and 4.0–5.0, 72.4–110.2 % and 364.8–551.0 respectively. Further, the greatest FI, CI, GI and VI values were recorded in the C5 compost, which inoculated the consortium which comprises Bacillus haynesii (PP391133), Bacillus amyloliquefaciens (PP391056) and Bacillus safensis (PP391033) strains. Consequently, the compost produced by the C5 consortium was categorized into the compost quality “A” category indicating its high quality and fertilizing potential. In contrast, the control compost belonged to the compost quality “D” category indicating the lowest quality. Thus, the results evidenced the potential applicability of the C5 consortium to produce good quality compost as a sustainable waste management approach.Item Photocatalytic degradation of microcystin-LR using nanostructured rutile and coir fibre(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Idroos, F. S.; Kottegoda, N.; Manage, P. M.Microcystins (MCs) are secondary metabolites of cyanobacteria, which tend to persist in the aquatic environment. Among 70 recorded analogues of MCs, Microcystin-LR (MC-LR) is the dominant and the most toxic cogener. Photocatalytic technology has been constantly recognized as a promising green approach in treating pollutants. The present study records the effective utilization of nanostructured rutile and coir fibre to treat MC-LR. Approximately 2 g of nanostructured rutile and coir fibre (100 nm) were coated in two separate glass slides and dipped in 100 µg/mL of filter sterilized lake water containing 50, 75 and 100 µg/mL of MC-LR. For both nanoparticles (rutile and coir fibre) at 50, 75 and 100 µg/mL of MC-LR concentrations, two experimental set ups (A-Exposed to sunlight, B-Exposed to 12 W UV light) and two control set ups (A1-Control exposed to sunlight, B1-Control exposed to 12 W UV light) were maintained. Sample aliquots of 1 mL was removed at every 30 minutes interval for a period of 3 hours. Subsequently, samples were subjected to freeze drying followed by reconstitution in 50% HPLC grade methanol and analyzed under PDA-HPLC to quantify the remaining MC-LR concentrations. Under the influence of UV light, nanostructured rutile showed, 100 % removal of MC-LR at 50 and 75 µg/mL within 1.5 hours and 2 hours respectively, whereas 87.4 ± 2.31% removal for 100 µg/mL of MC-LR was recorded at the end of 3 hours. When the same experiment was repeated by exposing to sunlight, MC-LR removal percentages were 77.29 ± 1.9 at 50 µg/mL, 36.4 ± 3.8 at 75 µg/mL and 19 ± 3.78 at 100 µg/mL. Moreover, when nanostructured coir fibre was used under 12W UV light, 100% removal of 50 µg/mL MC-LR, was evident at 2 hours, whereas 85.68 ± 9.4% for 75 µg/mL and 56.2 ± 4.37% for 100 µg/mL was observed at the end of 3 hours. At the exposure to sunlight, nanostructured coir particles showed 72.4 ± 2.3 at 50 µg/mL, 56.2 ± 8.2 at 75 µg/mL and 46.8 ± 6.98 at 100 µg/mL at the end of 3 hours. Two-way ANOVA confirmed that there is a significant difference in the MC-LR photocatalytic degradation ability of nanostructured rutile and coir fibre (P=0.02). Therefore, it could be concluded that nanostructured rutile is effective than coir fibre based nanoparticles in treating MC-LR contaminated water. Furthermore, UV exposure of both types of nanostructures can enhance photocatalytic degradation of MC-LR.