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Comparative study of nature and activities of soil fungi along with soil characteristics inKanneliya natural forest reserve and adjacent disturbed forest patch
(International Conference on Applied and Pure Sciences, 2025Faculty of Science, University of Kelaniya, Sri Lanka, 2025) Dissanayake W. G. M. P.; Kannangara S. D.; Ratnayake R. M. C. S.; Daranagama D. A. D. A.
Soil fungi in forests are crucial for ecosystem functioning by nutrient cycling through organic matterdecomposition. The Kanneliya forest reserve in Sri Lanka faces an ecological threat due to the invasionof the fern Dicranopteris Linearis, affecting the soil fungal community and challenging the restorationefforts. This study investigates the soil physicochemical properties along with substrate utilisationability of the dominantly isolated fungi in two ecosystems: the native forest patch and in adjacentdisturbed forest patch in the Kanneliya Forest Reserve. Soil pH, electrical conductivity, moisturecontent, and temperature were measured using standard methods. The Warcup soil plate method wascarried out using PDA medium to isolate soil fungi, and pure cultures of fungi were identified at thegenus level using morphological and microscopic observations. The percentage frequency ofoccurrence of each fungus was calculated separately for the two study sites. Aspergillus sp.1,Trichoderma sp.4, Rhizomucor sp.1, White sterile sp.1, and Trichoderma sp.5, the dominantly isolatedfungal species were tested for their substrate utilisation abilities (starch, cellulose and lignin) usingstandard methods. The soil temperature was significantly different within the adjacent disturbed land,but not within the native forest patch. The soil moisture content within the two study sites was notsignificantly different. The soil pH varied significantly within the undisturbed forest patch, but notwithin the disturbed land. The soil electrical conductivity within the two study sites was significantlydifferent. There were significant differences in soil electrical conductivity, moisture content, and pHbetween the two study sites, while soil temperature did not differ significantly. Among the isolatedeighteen (18) fungal species, 14 and 11 species were isolated from undisturbed and disturbed sites,respectively. Aspergillus sp.1, Aspergillus sp.2, Aspergillus sp.4, Trichoderma sp.3, Trichoderma sp.4,Trichoderma sp.5 and white sterile sp.1 were commonly isolated from both sites. Aspergillus sp.1,Rhizomucor sp.1 and White sterile sp.1 were able to utilise starch, and all fungi tested were able toutilise cellulose. Aspergillus sp.1, Trichoderma sp.4, White sterile sp.1, and Trichoderma sp.5 exhibitedthe ability to produce lignin-degrading enzyme(laccase), while none of the other fungal species testedwere able to produce peroxidase and tyrosinase, other lignin-degrading enzymes. The presentinvestigation provides insights into fungal composition and some physicochemical parameters inundisturbed and adjacent disturbed land in the Kanneliya forest reserve. Common fungal species to bothsites were isolated in a higher frequency of occurrence from the undisturbed forest patch compared tothe adjacent disturbed forest patch; this may be due to the presence of anti-fungal allelopathic chemicalsin the fern land. Further investigations on the allelopathic effect of Dicranopteris linearis on fungalgrowth are crucial to ensure the sustainability of the Kanneliya forest ecosystem.
Geospatial Profiling and Environmental Risk Analysis of Cadmium and Lead Dispersion in Dry Zone Soils and Sediments of Sri Lanka.
(Soil and Sediment Contamination: An International Journal, 2025) Dayananda, N. R.; Liyanage, J. A.; Kannangara, S. D.
This study delves into the contamination, spatial dispersion, and geoaccumulation of Cadmium (Cd) and Lead (Pb) in soils and reservoir sediments within Sri Lanka’s dry zone, emphasizing their environmental and public health ramifications, particularly in CKDu-endemic areas. Elevated concentrations of Cd and Pb in soils from Girandurukotte (GK), Kusumpokuna (KP), and Horowpathana (HP) originate from anthropogenic inputs, including intensive agriculture. The spatial distribution coupled with spatial autocorrelation (Moran’s Index values) of Cd (GK = -0.044, KP = -0.074, HP = -0.035) and Pb (GK = 0.197, KP = .181, HP = .314) in soils and sediments reflects mainly diffuse and clustered contamination patterns driven by agricultural runoff, irrigation practices, and geogenic sources. Cd showed considerable to very high contamination across sites, with Cf values ranging from 4.22 to 6.46, while Pb remained low to moderate (Cf: 0.23–2.01). The ecological risk was driven primarily by Cd, with Er values up to 193.8, resulting in PERI scores of 203.85 (HP), 169.50 (KP), and 132.75 (GK). These results highlight Cd as the dominant ecological concern in the study area. Irrigation networks facilitating the transport of Cd and Pb into reservoirs like Ulhitiya, Diwulankadawala, and Wahalkada, where sediment Igeo values indicate significant anthropogenic enrichment and demonstrated Cd concentrations exceeding sediment quality guidelines, such as LEL, CB-TEC, ERL, and SEPA. Cd, existing primarily as Cd2 +, demonstrates high mobility under slightly acidic conditions, forming soluble complexes and precipitating in reducing environments. Conversely, Pb exhibits reduced bioavailability due to its strong affinity for adsorption onto clay minerals, Fe-Mn oxides, and its precipitation as pyromorphite. Reservoir sediments, enriched with fine silts and clays, act as sinks for metal-laden runoff, while arid environmental conditions and cyclic irrigation-induced redox fluctuations further modulate metal speciation, mobility, and ecological risks, necessitating integrated soil and water management interventions.
Evaluation of Fermentation Dynamics and Volatile Compound Profiles of Pro biotic Lactobacillus spp. Inhabiting! Tender Coconut Water
(ICIET/Food Security, Nutrition, and Processing Technology, 2025) Pavalakumar, D.; Undugoda, L.J.S.; Managec, P.M.; Nugara, N.N.R.N.; Kannangara, S.
Lactic acid bacteria fermentation of tender coconut water creates a beverage with enhanced probiotic and biopreservation properties. This study examines the potential fermenters with a preferred volatile profile among four indigenous lactic acid bacteria inhabiting tender coconut water: Lactiplantibacillus plantarum CWJ3, Lacticaseibacillus rhamnosus CWKu-12, Lacticaseibacillus paracasei CWKu-14, and Lacticaseibacillus casei CWM15. The lactic acid bacteria strains were cultured in de Man, Rogosa, and Sharpe broth, and inoculated into pasteurized tender coconut water. Their fermentation characteristics were monitored over 48 hours at 37 °C, and volatile profiles were analyzed using gas chromatography-mass spectrometry coupled with solid-phase microextraction (GCMS-SPME). In all samples, pH and residual sugar levels consistently decreased, while viable cell counts increased during fermentation. L. plantarum CWJ3 exhibited the significantly lowest pH (3.86±0.26) and Brix (3.78±0.54) values while maintaining high cell viability (5×10⁶ CFU mL-1). This strain also demonstrated relatively stable viable cell productivity (78,194 to 102,950 CFU mL-1h-1), and a growth rate (0.0417 to 0.0516 h -1), making it the most suitable strain for fermentation. GCMS-SPME analysis confirmed the production of acids, esters, ketones, lactones, and aldehydes during fermentation. L. plantarum CWJ3 produced the significantly highest amounts of acetic acid (13.12±1.21%), and acetaldehyde (1.25±0.23%), and the lowest ethanol levels (4.56±0.87%). Conversely, L. rhamnosus CWKu-12 produced elevated levels of ketones and lactones, such as 2-heptanone (8.15±1.02%) and 2,3-butanedione (4.16±0.81%), contributing to a unique volatile profile. Ethyl acetate was the primary ester produced by all strains, with L. paracasei CWKu-14 generating the significantly highest amount (7.65±0.54%). Notably, L. plantarum CWJ3 was the only strain to produce ethyl isobutyrate. The volatile compounds from L. plantarum CWJ3 and L. rhamnosus CWKu-12 contribute to a fruitier flavor, while their increased acetic acid and reduced ethanol levels enhance the product’s biopreservation.
Comprehensive In Vitro Evaluation of the Biocontrol Potential of Trichoderma virens Against Selected Phytopathogenic Fungi: Integration of Interaction Dynamics and Best-Fit Mathematical Modeling
(Asian Journal of Mycology, 2025) Munasinghe, J; Poornima V.A; Dissanayake, T.; Kannangara, S; Undugoda, L; Thambugala K.M
In the context of plant disease management, biocontrol is often used as an environmentally friendly alternative to synthetic chemical pesticides. The genus Trichoderma is known for its ability to suppress various plant diseases caused by pathogenic fungi through antagonism, competition, and induced resistance. This research attempt was to evaluate the mechanisms employed by Trichoderma virens isolate (KP985643.1) in controlling three plant pathogenic fungi (Fusarium oxysporum, Colletotrichum gloeosporioides, and Lasiodiplodia theobromae) under in vitro conditions, along with the selection of the best-fitting mathematical models for their interactions. The biocontrol potential of T. virens against the selected plant pathogenic fungi was evaluated using the dual culture method. Further biocontrol mechanism was identified using the analysis of volatile and non-volatile compounds and the hyphal growth patterns. In addition to that the results of the dual culture method were used to analyse the best-fitting growth models for each pathogenic fungus separately for two conditions which were in the absence of T. virens and in the presence of T. virens. These mathematical models of microbial growth serve as powerful tools for predicting the future performance of fungal biocontrol agents in managing plant diseases under diverse environmental conditions. Such predictive capabilities are crucial for optimizing field applications, improving consistency in biocontrol outcomes, and supporting the development of sustainable, environmentally friendly plant disease management strategies in agricultural systems. Results of the dual culture experiment demonstrated a significant growth control of L. theobromae and F. oxysporum and a moderate growth control of C. gloeosporioides by T. virens. Considering the growth models, the best fitted models were given by Gompertz, Exponential, and Exponential, respectively, for C. gloeosporioides, F. oxysporum, and L. theobromae in the absent condition of T. virens. In the present condition of T. virens, the best-fitted models were given by Brody, Exponential, and Brody respectively for L. theobromae, C. gloeosporioides, and F. oxysporum. The increase in volatile production was not uniform across all pathogens. For instance, the highest VOC production showed against F. oxysporum, suggesting that T. virens may be more efficient at preventing F. oxysporum from producing volatile compounds. Among many VOCs, ethanol and 6-Pentyl-2H-6-Pentyl-2H-pyran-2-one production were the highest when T. virens controlled the growth of F. oxysporum. However, non-volatile compounds produced by T. virens significantly controlled the growth of L. theobromae, with a moderate inhibition of F. oxysporum. It was further observed the ability of T. virens to inhibit the growth of L. theobromae through the production of coiling structures. Results of the present study clearly indicated the potential of T. virens in controlling the tested phytopathogenic fungi by employing a combination of mechanisms including the production of volatile and non-volatile compounds and hyphal interactions.
Kinetic evaluation of anthracene biodegradation by Bacillus velezensis and mathematical model fitting under substrate inhibition conditions.
(Bioremediation Journal, 2025) Nadeema Dharmasiri, R. B.; Munasinghe, J.; Madushika, R.; Pavalakumar, D.; Samarakoon Undugoda, L. J.; Kannangara, S. D.; Thambugala, K. M.
Polycyclic aromatic hydrocarbons (PAHs) such as anthracene are persistent environmental pollutants that accumulate in ecosystems and contribute to harmful air pollution, posing risks to human health. Due to its significance, anthracene must be removed using nontoxic methods such as bioremediation. This study focuses on degrading anthracene with Bacillus velezensis and investigating the kinetics of this process. The bioremediation potential of B. velezensis in degrading anthracene under aerobic conditions was explored through batch experiments conducted at varying anthracene concentrations (100–600 ppm). The bacterium exhibited rapid biomass growth and efficient degradation at 100 ppm, while growth was inhibited at higher concentrations due to substrate toxicity. GC-MS analysis identified 9,10-anthracenedione as the primary intermediate, which was further broken down into carbon dioxide and water at 100 ppm. Phytotoxicity assays confirmed this intermediate was nontoxic to the bacterium and phyllosphere. The degradation kinetics deviated from the Michaelis–Menten model at high concentrations, indicating the influence of substrate inhibition. Among several models evaluated, the Wayman and Tseng model showed the best statistical fit, with a high adjusted R2 value (0.95191) and a low RMSE (0.0019), indicating accurate predictions. Data interpolation improved model performance, providing a more reliable framework for predicting anthracene degradation by B. velezensis.