Browsing by Author "Peiris, S. E."

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Open Access
Effects of Green Synthesized Copper-Derived Nano Particles extracted from Piper betel to Eliminate Contaminations in tissue culture of Dracaena sanderiana Sander ex Mast. cv ‘Gold’
(Department of Applied Sciences. Faculty of Humanities and Sciences,SLIIT, 2025-10-10) Gunawardana, R.; Peiris, S. E.; Peiris, C. N.; Jayasinghe, S.
Micropropagation is often hindered by contamination from endophytic microbes. While antibiotics are used to eliminate these without harming plant tissues, they risk promoting antibiotic resistance. This study explores a green alternative by synthesizing copper nanoparticles (Cu-NPs) using antimicrobial-rich Piper betel leaf extract. The eco-friendly method uses plant biomolecules as natural reducing and stabilizingagents. The aim was to (i) produce Cu-NPs via eco-friendly plant-based synthesis, (ii) evaluate their antibacterial activity against Escherichia coli and S. aureus, and (iii) assess their effectiveness in reducing microbial contamination in plant tissue culture. Cu-NPs were produced by reacting leaf extract with cupric sulphate under controlled heating and stirring. Their antibacterial activity was tested against E. coli and Staphylococcus aureus via time-kill assays, and their efficacy in reducing contamination was assessed by applying them to Dracaena sanderiana explants in vitro. 200 ppm was identified as the optimal concentration for the antibacterial activity in in vitro establishment trials of Dracaena sanderiana, 50 ppm Cu-NPs proved to be the most effective concentration, resulting in 100% survival when used both for surface sterilization and as a supplement in the culture medium, and 80% survival when used only for surface sterilization. Thefindings suggest that green-synthesised Cu-NPs from P. betel show potential as an alternative to antibiotics in plant tissue culture, with promising effects on contamination control and reduced risk of antibiotic resistance.
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Facile synthesis of silver/iron-TiO2 nanoparticles for sterilization of Nodal explants of Dracaena sanderiana Sander ex Mast. cvs ‘Gold’ and ‘Victory’ and growth regulator effects on in vitro growth
(OICC Press, 2025-02-08) Seneviratne, K.L; Peiris, S. E.; Peiris, C. N; Shashikala, R. P. A; Jayasinghe, S; Kottegoda, N
This study investigates the application of silver/iron-titanate (Ag/Fe-TiO2) nanoparticles (NPs) as a sterilizing agent for in vitro cultures of Dracaena sanderiana cultivars ‘Gold’ and ‘Victory’. The motivation behind this research is to find an effective sterilization method that does not harm plant growth. The Ag/Fe-TiO2 NPs, activated by visible light, exhibit catalytic properties that eliminate harmful microbes such as Escherichia coli, Staphylococcus aureus, and Fusarium spp. The main findings indicate that the combination of Benzyl Amino Purine (BAP) at 1.5 mg/L and Indole Acetic Acid (IAA) at 0.01 mg/L significantly enhances shoot number and length in both cultivars. The use of 200 mg/L Ag/Fe-TiO2 NPs achieved 90% contamination-free cultures in the first cycle, with a slight decrease to 80% in the second cycle and 70% in the third cycle. Importantly, the treatment not only sterilizes but also promotes plant growth, suggesting that Ag/Fe-TiO2 NPs could be a sustainable solution for in vitro plant mass production. © 2025 The Author(s)
Open Access
In Vitro Evaluation of Antibacterial Activity of Copper and Sulfur Nanoparticles for Controlling Bacterial Blight Caused by Xanthomonas sp. in Anthurium andraeanum Lind.
(Faculty of Humanities and Sciences, SLIIT, 2022-10-20) Peiris, S. E.; Seneviratne, K. L.; Shashikala, R. P. A.; Peiris, Colin N.; Imalka, M. I.; Piumika, Y. P
Bacterial blight in Anthurium andraeanum Lind. which is caused by Xanthomonas sp. is regarded as the most threatening disease in the anthurium industry worldwide. Therefore, the current study was carried out to determine whether the application of copper nano particles (CuNPs) and sulfur nanoparticles (SNPs) is a possible solution to control the bacterial blight in anthurium. The bacterium Xanthomonas sp. was isolated using standard methods and a single bacterial colony was grown in nutrient agar (NA). The colonies produced in cultures were identified as Xanthomonas sp. as they were Gram-negative, motile rods with yellow colour due to production of xanthin. The symptoms appeared in the pathogenicity test which was carried out by injecting purified Xanthomonas sp. into disease free anthurium plants confirmed the identification of the bacterial strain. Concentrations of 5, 15 and 25mg/100ml CuNPs and 50, 75 and 1000 mg in 100ml SNPs were mixed separately with isolated Xanthomonas sp. to investigate the behavior of two types of nano particles in destroying the bacterium. All three concentrations (5, 15 and 25 mg/100ml) of copper nanoparticles used in suspensions of the bacterium Xanthomonas sp. did not support any bacterial growth. In contrast, all three concentrations of SNPs in Xanthomonas sp. showed bacterial growth though it was less in 1000 mg /in 100ml compared to the control treatment. Hence it can be concluded that 5 mg/100 ml CuNPs is capable of destroying in vitro growth of Xanthomonas sp. bacterium which causes bacterial blight in Anthurium andraeanum.
Open Access
Microbial Pigment Isolation, Culturing, and Extraction to Use as Textile Dyes
(Faculty of Humanities and Sciences, SLIIT, 2024-07-26) Hewagama, H. L; Somarathna, G. M. T. K.; Herath, L.; Peiris, S. E.
The textile industry is one of the largest worldwide polluters of clean water due to the heavy use of synthetic dyes. These chemicals negatively affect the environment, especially aquatic life due to their toxic and mutagenic properties. Synthetic dyes cause harm to human health such as skin allergies and respiratory sensitization. Several advantages such as ease of extraction, availability, high yields and no seasonal variation make microbial pigments the most ideal source of natural pigments. This study was done to isolate colour pigment producing bacteria and fungi from soil collected from organic farms from various locations in Sri Lanka. Out of 7 soil samples, 3 yielded pigment producing bacteria and fungi. In total, 9 pigment producing bacteria and 3 pigment producing fungi were isolated. Gause’s synthetic agar yielded the most pigmented isolates. Isolates were inoculated in broths and pigment production was observed. Extracellular pigments produced by 5 of the bacterial isolates were extracted by a water-based method. The antibacterial activity of the pigments in their crude and concentrated forms was tested using the well diffusion method against Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 6538P. Inhibition zone against S. aureus was observed for both crude (12.33±0.58mm) and concentrated pigments (9.67±0.58mm) extracted from purple pigment producing bacterial isolate (BPU). This pigment has the potential to be used in antibacterial textile preparation. Extracted pigments were used to dye scoured cotton fabric with the use of 3% alum as mordant. Pigment from BPU isolate resulted in better coloured fabric.