Browsing by Author "Ratnayake, R. D"

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Embargo
In Vitro Antibacterial Activity of Sulphur Nanoparticles as a Possible Application to Control Bacterial Blight Caused by Xanthomonas spp. in Anthurium
(Faculty of Humanities and Sciences, SLIIT, 2022-09-15) Peiris, S.E; Malwattage, G; Ratnayake, R. D; Seneviratne, K .L; Peiris, C.N
Anthurium blight is caused by Xanthomonas spp. which is regarded as the most threatening disease to the anthurium industry worldwide. Therefore, the current study was carried out to determine whether the application of sulphur nanoparticles (SNPs) is a possible solution for treating anthurium cultivars infected with Xanthomonas spp. The bacterium Xanthomonas was isolated using standard methods and a single bacterial colony was isolated using nutrient agar. The colonies were identified as Xanthomonas spp as they were gram-negative, motile rods due to the colony characters like yellow color because of the xanthin produced. 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. Time-kill assay was conducted using Staphylococcus aureus, Escherichia coli and isolated Xanthomonas spp to investigate the behavior of SNPs. The results showed that suspension treated with 1g of SNPs for 30 minutes inhibited growth of Staphylococcus aureus colonies showing mean number of 7.92 CFU/ml compared to the control (mean number of colonies 9.09 CFU/ml ) treatment following 12 hours incubation. However, Escherichia coli, and isolated gram-negative rods (Xanthomonas spp) did not show positive influence for SNPs when compared to the control treatment. Therefore, further investigation is required to reach firm conclusions about this matter because the antimicrobial activity of SNPs varies depending on the type of target microorganisms, method and solvent used to dissolve SNPs.
Open Access
A Novel Surface Sterilization Technique for in vitro Establishment of Dianella tasmanica variegata Nodal Explants
(researchgate.net, 2021-12) Malwattage, G; Ratnayake, R. D; Seneviratne, K. L; Peiris, S.E; Peiris, B. C. N
Dianella tasmanica ‘variegata’ is one of the popular species which is exported as ex-agar plants from Sri Lanka. In order to promote dianella exports, micropropagation should be increased to produce a high-quality large number required by the export markets. However, severe microbial contaminations in the in vitro establishment have become the bottle neck for large scale in vitro propagation of this species. Therefore, this study was undertaken with the objective of using sulfur nanoparticles (S-NP) to eliminate surface adhered fungal and bacterial contaminants to obtain a vast number of contamination-free cultures at the in vitro establishment stage. Apical parts of about 6 cm of D. tasmanica were used in this study. Effects of S-NP solution in 500 mg/L was used with the control of 10% Clorox™ for the surface sterilization of the nodal explants. Results revealed that 500 mg/L S-NP produced 80% and CloroxTM produced 40% contamination-free cultures after 4 weeks of establishment in vitro. The experiment was repeated twice. This study suggests that S-NP is a promising lowcost non-toxic material that can be used in the surface sterilization of dianella nodal explants.