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Item Biodeterioration of low density polyethylene by Montagnula scabiosae(Faculty of Science, University of Kelaniya, Sri Lanka, 2021) Perera, T. W. N. K.; Attanayake, R. N.; Paranagama, P. A.Endolichenic Fungi (ELF) are a group of fungi adapted to live within lichen thalli. Present study investigates the ability of Montagnula scabiosae, an ELF, for biodeterioration of low density polyethylene (LDPE) by determining the activity of three extracellular fungal enzymes, reported to have potential roles in depolymerizing polyethylene, using enzymatic assays. Liquid medium screening assays, using four potato dextrose agar (PDA) plugs (0.5 cm diameter) of ELF cultures, inoculated into Erlenmeyer flasks containing sterile mineral salt medium broth (MSMB). Eight sterile LDPE strips (10 cm x 3 cm) were added into each flask and incubated at room temperature (28 ± 2°C) for 21 days. MSMB flasks with plain PDA plugs and sterile LDPE strips were used as the controls. Solid medium biodeterioration studies also were conducted using three PDA plugs of the ELF cultures inoculated into mineral salt medium agar (MSMA) plates. Eight sterile LDPE strips were aseptically placed on the surface of each MSMA plate and incubated at room temperature for 45 days. MSMA plates with plain PDA plugs and sterile LDPE strips were used as the controls. Both liquid and solid media assays were carried out in four replicates. LDPE biodeterioration was analyzed based on reductions in weights and tensile properties, changes in peaks of Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectra, changes in carbonyl index (CI) and Scanning Electron Microscopic (SEM) images. A distinguishable LDPE deterioration ability was shown by Montagnula scabiosae, isolated from the host lichen Pyrenocarp sp. Results showed that isolate reduced weights of strips by 13.22% in liquid medium and by 12.06% in solid medium. Tensile strength of liquid medium treated strips, reduced by 6.64% and solid medium treated strips, by 3.00%. The control LDPE strips on ATR-FTIR analysis showed four prominent peaks at 2916 cm-1, 2848 cm-1, 1463 cm-1 and 720 cm-1 and a few minor peaks. Changes visible in the ATR-FTIR spectra of treated strips, manifested new peaks, fluctuations in percentage transmittance and deletions of existing peaks. CI value of the LDPE strips in liquid medium were found to be increased by 2.70% and in solid medium increment was 2.31%. SEM images of treated strips showed erosion zones on LDPE matrix. Qualitative enzymatic assays using Agar plate-based screening methods, indicated the presence of laccase and peroxidases, in this ELF isolate. In the quantitative enzymatic assays, M. scabiosae showed laccase, lignin peroxidase and manganese peroxidase activities as 1.07×10-7 kat L-1, 1.22×10-8 kat L-1 and 2.10×10-8 kat L-1 respectively. Remarkable LDPE deterioration ability shown by this ELF isolate indicates that it has a high potential in degrading LDPE waste.Item Polyethylene degradation capability of Schizophyllum commune(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Perera, T. W. N. K.; Attanayake, R. N.; Paranagama, P. A.Tremendous increases in the manufacture and consumption of polyethylene, over recent decades have led to numerous environmental and economic concerns. This is the first comprehensive research on determination of Endolichenic Fungi (ELF), capable of degrading polyethylene substrates. The objective of this study was to identify the ability of various ELF, for the degradation of polyethylene in liquid media. Commercially available Low Density Polyethylene (LDPE) bags were used as the test material. ELF isolates cultured on Potato Dextrose Agar, were introduced into Mineral Salt Medium Broth containing LDPE strips. The isolate, Schizophyllum commune showed a positive growth response in the broth medium. The strips treated with this isolate, were tested for the reduction in dry weight, changes in peaks of Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy, reduction in tensile strain at break and changes in Scanning Electron Microscopic analyses. Results showed that isolate, reduced the weight of LDPE strip by 10.54%, after 21 days of incubation, while control showed 0% reduction. The control LDPE strip on ATR-FTIR analysis showed prominent peaks at 2916 cm-1, 2848 cm-1, 1463 cm-1 and 720 cm-1. Changes visible in sample infrared spectra after 21 days of incubation, were the fluctuations in the percentage transmittance of above peaks and formation of new peaks at 1740 cm-1, 1215 cm-1 and 1046 cm-1. The tensile strain at break, of treated strips, reduced by 27.41%, after 21 days of incubation while control showed 0% reduction. The presence of pits and cavities, in Scanning Electron Micrographic images, suggested the penetration of fungi, into the LDPE matrix, during degradation. The occurrence of several nonuniformly scattered whitened areas and erosion zones, indicated the surface erosion of LDPE strips, in degradation. These changes were not observed in the control LDPE strips. This study provides insight into the role of Schizophyllum commune towards solving the dilemma of polyethylene wastes, through biodegradation.Item Microbial enumeration assay of fermented products of cassava variety MU51(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Perera, T. W. N. K.; Amarakoon, R.; Edirisinghe, E. A. A. D.This study was carried out to investigate the effects of solid state fermentation of cassava variety MU51, on the qualitative properties and total viable microbial counts, of the fermented cassava products, developed by changing the fermentation lengths as two days and three days. The steps involved in the product development are peeling, washing, grating cassava roots into a mash, collecting the mash into sacks, dewatering and fermenting the mash under natural environmental conditions. The fermented, wet cakes obtained are further de-watered by oven-drying process to make fermented, dry products. These fermented dry cassava products appear cream-white in color and soft granular or powdered form in texture. Both products have a fermented smell and the pH value is 5. Microbial enumeration assay is carried out for the raw cassava, fermented wet cakes and fermented dry products, using plate count technique. Particular attention is given on mesophilic, aerobic and facultative anaerobic microorganisms. The bacterial count of raw cassava is (1.8-2.2) x10³ colony forming units per gram. For two days fermented wet cake, the bacterial count is (2.9-3.4) x10⁴ colony forming units per gram and for three days fermented wet cake, it is (2.8-3.3) x10⁴ colony forming units per gram. During fermentation, the bacterial count increases. Increase of acidity during fermentation and depletion of substrates could contribute to a slight decrease in the viable bacterial population, during later stage of fermentation. The fungal count of raw cassava is (6.3-8.6) x10² colony forming units per gram. Fungal count of two days fermented wet cake is 8.5x10² - 1.1x10³ colony forming units per gram and three days fermented wet cake is (1.1-1.3) x10³ colony forming units per gram. During fermentation, the fungal count increases as fungi are favored by the acidification of pulp and are benefited from the metabolites sourced from the growth of other microorganisms. Bacterial count of two days fermented dry product is (2.7-3.2) x10⁴ colony forming units per gram and three days fermented dry product is (2.6-3.0) x10⁴ colony forming units per gram. Fungal count of two days fermented dry product is (7.4-8.6) x10² colony forming units per gram and three days fermented dry product is 9.4x10² - 1.2x10³ colony forming units per gram. This plate count assay can be used as an index to evaluate the microbial content, in order to provide a microbiological specification for the fermented cassava products. Fermented cassava products would be an ideal option that reduces the post-harvest losses of raw cassava.