Browsing by Author "Premetilake, M.M.S.N."

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    Antibacterial Activity of Silver Deposited Vein Graphite against Waterborne Pathogenic Escherichia coil
    (Uva Wellassa University of Sri Lanka, 2018) Kumar, K.K.A.D.; Amaraweera, T.H.N.G.; Premetilake, M.M.S.N.; Wijayasinghe, H.W.M.A.C.
    The microbial contamination of drinking water is a major health problem in the world which requires an effective treatment. Silver ion (Ag+2) is used as nonspecific antibacterial factor and it acts against a very broad spectrum of bacterial species. In this study, antibacterial efficiency of Ag deposited vein graphite were studied using Escherichia coli strain. Ag was deposited on the graphite surface by reduction of Ag+2 in silver nitrate solution using reducing agent. Scanning electron microphotographs of the Ag deposited graphite reveal that the deposited silver particles are highly agglomerated or spongy voids. Although the size of silver particle agglomerates are relatively coarse, the average size of individual silver nanoparticle is around 75 nm. Antibacterial efficacy of the synthesized sample was investigated using waterborne pathogenic E. coli strain. The antibacterial test was done using prepared composite samples and samples of E. coli, using shake flask method. A commercial antibiotic (Ofloxin-200 mg) was used as the positive control. The samples were drawn periodically (1, 1.5, 2, 2.5 and 3 hours) from the flask and tested against E. coli by plate count method using standard procedures. There was a significant E. coli removal efficiency by the synthesized Ag Graphite composite compared to purified graphite and positive control (One-way ANOVA, p-value=0.00). Therefore, this study suggests that Ag- vein graphite composite could be used as an effective material in water purification, especially in removing of E. coli.
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    Assessment of Quality of Drinking Water in Selected Areas of Badulla District: An Approach to Causative Factors for Chronic Kidney Disease of Unknown Etiology (CKDu)
    (Uva Wellassa University of Sri Lanka, 2019-02) Rathnayake, R.M.M.L.; Purathini, M.; Henagamage, A.P.; Premetilake, M.M.S.N.
    Chronic Kidney Disease of unknown etiology (CKDu) is one of the major health issues in Sri Lanka. Though the main reason for the CKDu has not yet been identified, it is suggested that this is due to multi-factorial effect. However, it strongly correlates with certain drinking water quality parameters. Hence, this study was aimed on evaluating the quality of drinking water sources in CKDu potential areas in Badulla district and compare with the Sri Lanka Standard (SLS) water quality admissible levels. Drinking water samples were collected from dug wells in CKDu potential areas in Uva Province; Lower- Rathkinda, Ginnoruwa, Rideemaliyadda and Uva Paranagama (control area). Parameters such as pH, electrical conductivity, anions and heavy metals were analyzed following standard methods. Data were analyzed by one sample T- test, using IBM SPSS statistics 21.0 version. Mean values of pH value, electrical conductivity, chloride levels, nitrate levels and hardness of water samples of all the areas were within the acceptable range for portable water according to the standard SLS 614:2013. Mean fluoride contents and phosphate contents of all potential CKDu areas were less than the stipulated standard levels while Uva Paranagama exceeds the standard levels. Cadmium, as one of the most suspected causative heavy metal for CKDu, showed significantly higher level (P<0.05) than that of the admissible level of 0.003 mg L-1 in Lower- Rathkinda (0.005± 0.001 mg L-1) and Ginnoruwa (0.006± 0.001 mg L-1). Control area showed a higher Cd level (0.04± 0.002 mg L-1, P>0.05) than that of the permissible level whereas Rideemaliyadda (0.002± 0.002 mg L-1, P>0.05) shows lower levels than the permissible level. Lower- Rathkinda and Ginnoruwa areas showed higher levels of iron than that of the standard level of 0.3 mg L-1. Due to the high content of Cd levels in all the water samples, the water sources are at a risky status for drinking purpose even though the other parameters showed safe levels.
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    Correlation of Ground Water Fluoride with Total Hardness and Total Alkalinity in CKDu Prevalent areas in Uva Province
    (Uva Wellassa University of Sri Lanka, 2020) Rathnayake, R.M.M.L.; Henagamage, A.P.; Premetilake, M.M.S.N.; Udagedara, D.T.
    Chronic Kidney Disease of unknown etiology (CKDu) describes as a multifactorial effect. Thus, postulates on CKDu focus on the cumulative effect of nephrotoxic contaminants which deteriorate the kidney function progressively. This study aimed to determine the influence of total hardness (TH) and total alkalinity (TA) on fluoride (F-) content of groundwater in CKDu prevailing areas in Uva Province. Divisional secretariats of Mahiyangana (MDS), Rideemaliyadda (RDS), Wellawaya (WDS), and Siyambalanduwa (SDS) were selected as CKDu prevailing areas for sample collection. Water samples from 45 dug wells were collected by following a simple random sampling method and the samples were triplicated. Samples were analysed by standard methods of water analysis (APHA 1985). Statistical data analysis was carried out using IBM SPSS 21.0 software. The range of F- contents in MDS (n= 17), RDS (n= 8), WDS (n= 11) and SDS (n=9) were 0.01– 1.80±0.08 mg L-1 , 0.02 – 0.61±0.13 mg L-1 , 0.01±0.01- 5.8±0.1 mg L-1 and 0.17±0.02– 1.42±0.11 mg L-1 respectively. The highest mean value for TH was observed from WDS (156.44±21.53 mg L-1 ) and the least was observed from RDS (116.36±21.95 mg L-1 ). All the mean values for TA were recorded within the permissible level according to WHO guidelines for drinking water and the highest was observed from WDS (336.36±117.58 mg L-1 ). Results of the linear regression analysis on the dependence of Fon TH indicated a positive correlation in MDS, WDS, and SDS as well as a negative correlation (r= - 0.33) in RDS. All the test areas were observed with positive correlations between F- content, and TA. Among the selected DS areas, 44% of the water samples in SDS, 36% of the water samples in WDS, 12% of the water samples in MDS, and 0% of the water samples in RDS exceeded the maximum permissible level for F- defined by WHO. The influence of total hardness and total alkalinity on Fluoride content in groundwater is required to be studied further. Keywords: Fluoride, Total Hardness, Total Alkalinity, CKDu, Uva Province
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    Effect of Methanolic Extracts of Emilia sonchifolia (Lilac tassel flower), Ageratum conyzoides (Billy goat weed) and Mikania micrantha (Bitter vine) on Protease Enzyme Inhibition
    (Uva Wellassa University of Sri Lanka, 2018) Nisrina, M.N.; Alakolanga, A.G.A.W.; Premetilake, M.M.S.N.; Wijesekara, K.B.
    According to previous studies, methanolic extracts of Emilia sonchifolia, Ageratum conyzoides and Mikania micrantha have shown significant antimicrobial activity against Staphylococcus aureus. But their mode of action on the microorganisms is still unknown. It is expected that these three plants may have acted as protease inhibitors in the respective microorganism. So in the present study, 40 g of shade dried leaves of each plants, E sonchifolia, A. conyzoides and M. micrantha were extracted using methanol and subsequently subjected to solvent-solvent partitioning using hexane, chloroform and ethyl acetate. Those fractions were evaporated to obtain concentrated fractions. Then these concentrated fractions were used to prepare four concentration gradients, such as: 250 𝜇g ml-1, 500 𝜇g m1-1, 750 𝜇g m1-1 and 1000 𝜇g m1-1 and tested against protease enzyme. The protease enzyme assay was carried out based on Kunitz method, using casein as the substrate. According to the results obtained, highest inhibitory percentage was shown by E. sonchifolia. Even though statistical output has shown a significant difference of inhibition percentage among the concentration gradient of the plant fractions used (p value = 0.000), the range of the values are narrowed from 83.8% and 93.5% only for all three plants. So the results do not confirm the protease inhibitory activity of the extracts of the selected plants. Protease inhibitors control the action of proteases that are vital for the growth and development of the organism. Therefore, the reason for the antimicrobial activity of the methanolic extracts of these plants may not be due to protease inhibitory reaction but due to some other reasons.
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    Effect of α-Pinene on the Soil Bacterial and Fungal Population and Soil Organic Carbon in Eucalyptus Plantations
    (Uva Wellassa University of Sri Lanka, 2019-02) Dahanayake, P.M.; Premetilake, M.M.S.N.; Henegamage, A.P.; Herath, H.M.S.K.
    Nutrient cycling is essential for the stability of an ecosystem where soil microorganisms play a significant role. Some allelochemicals such as α-pinene produced by certain plant species may suppress the activity of these microorganisms. Eucalyptus, which is a popular plantation species in Sri Lanka, is known to emit α-pinene. However, its effect on soil microorganisms and soil fertility is not well known. The present study investigated the relationship between α-pinene content, soil microorganisms and soil organic carbon content in 7-year-old Eucalyptus grandis and Eucalyptus torelliana plantations. As the control plantation, an adjacent Patna grassland (previous land-use before afforestation) was used. Three subplots (20 × 20 m) were established within each site and soil was sampled up to 15 cm depth. Soil organic carbon content was measured according to the Walkley-Black method. Following a serial dilution, bacteria and fungi were cultured and CFU mL-1 was calculated. The α-pinene in soil samples was extracted using petroleum ether and was analyzed using GC-MS. According to the results, there was a significant (P<0.05) variation between organic carbon, α-pinene content and bacteria quantity between the plantations and the adjacent grasslands. However, there was no significant (P>0.05) variation in fungi quantity. The highest organic carbon content was observed in E. torelliana plantation (2.08% ±0.3), however; the highest α-pinene content was found under E. grandis plantation (0.14% ± 0.09). Interestingly, the highest bacterial count was recorded under E. grandis plantation (3.0 x 105 CFU mL-1) while the highest fungi count was recorded in grassland. There were no significant (P>0.05) correlations between the soil α-pinene content, soil bacterial and fungal count fungal and the organic carbon. There is no significant effect (P>0.05) of α-pinene content on the bacterial and fungal counts and organic carbon in young E. grandis and E. torelliana plantations.
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    Evaluation of Combined Antimicrobial activity of Leaf Extracts of Psidium guajava and Moringa oleifera against Staphylococcus aureus
    (Uva Wellassa University of Sri Lanka, 2018) Daundasekara, D.M.C.P.; Premetilake, M.M.S.N.
    The combined effect of diverse plant extracts on microorganisms is a highly effective, new approach in modern pharmaceutical industry due to its excessive capability in treatment of serious infectious diseases caused by multidrug resistant bacteria. The purpose of this study is to determine the synergistic effect of Psidium guajava and Moringa oleifera against Staphylococcus aureus. In this study leaves extracts of P. guajava and M oleifera plants were tested in different concentrations individually and in different volume combinations (1:1, 2:1, 1:2) against S. aureus. Healthy plants leaves were selected, washed, dried and were grounded into a fine powder. Each plant material was extracted in a Soxhlet using methanol. Different dilutions of the resulting crude extracts were prepared separately to give final concentration in the range of 100, 80, 60, 40, and 20 mg mL-1 using methanol as the solvent. The two extracts of the same concentration were mixed in three different combination (volume) ratios (1:1, 2:1, and 1:2) to obtain solutions with a final volume of 30 mL. Agar-well diffusion method was used to investigate the synergistic antimicrobial activity. Resulting inhibition zones were compared with the commercially available antibiotic, Ofloxacin. The minimum inhibitory concentration 80% were 7.91 and 24.45 mg mL-1 respectively for P. guajava and M. oleifera. According to the results, antibiotic showed significantly high mean inhibitory zone diameter compared to different concentrations of extracts. With the increment of the concentration, the inhibition value increased except for the values obtained for combinations at concentration 20 mg mL-1. The acquired data concluded that the synergistic antimicrobial effect of these two plants was less effective than their individual activity at high concentrations. However, the results revealed that at low concentration of 20 mg mL-1, the synergistic antimicrobial effect of P. guajava and M. oleifera was increased for the volume ratios of 2:1 and 1:1(v/v) which shows the antimicrobial potential of combined leaf extract.
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    Extending Shelf Life of Tomatoes Using Microbial Antagonists
    (Uva Wellassa University of Sri Lanka, 2019) Thivijan, S.; Premetilake, M.M.S.N.
    The current methods used to extend the shelf life of tomatoes are expensive and toxic, thus inexpensive and nontoxic methods are required to extend their shelf life. Objective of this study was to extend the shelf life of tomatoes using fruit peel extracts. Peel extracts were prepared from sweet orange (Citrus sinensis), lime (Citrus aurantiifolia) and sour orange (Citrus aurantium) peel using a rotary evaporator. From the extracts 2.5 mg mL-1, 1.25 mg mL-1 and 0.625 mg mL-1 concentration series were prepared. Most abundant microbial species were isolated from rotten tomatoes and tentatively identified as Bacillus sp. and Penicillium sp. The antimicrobial activities of three peel extracts were tested by using agar well diffusion assay. Positive controls for bacteria and fungi were Amoxicillin and Fluconazole, respectively, and 50% ethanol was the negative control. There were significant differences between Mean Inhibition Zone Diameters (MID) of different concentrations (P<0.05). Both concentration and type of extract significantly affected for MID (P<0.05). Although the highest MID was resulted from positive controls (2.6±0.3 cm, 3.4±0.4 cm for Amoxicillin and Fluconazole, respectively), sweet orange peel extracts had shown highest MID of 2.5±0.8 cm and 2.1±0.3 cm (at 2.5 mg mL-1) for both bacteria and fungi, respectively, compared to other peel extracts. A solution of sweet orange peel extracts (2.5 mg mL-1) was then prepared and sprayed on a batch of tomatoes (ripen) belonging to same variety and same size, while Amoxicillin and Fluconazole solution and distilled water were sprayed on another three batches of tomatoes. The shelf life of sweet orange peel extract solution sprayed batch was 26 days in average while that of batches sprayed with Amoxicillin, Fluconazole and water were 19, 20 and 5 days in average, respectively. Therefore, sweet orange peel extracts could be used to prepare antimicrobial solutions to extend the shelf life of tomatoes.
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    Investigating Variation of Microbial Biomass in Plantation Forests with Age
    (Uva Wellassa University of Srilanka, 2011) Premetilake, M.M.S.N.; Rathnayake, R.R.; Kulasooriya, S.A.; Perera, G.A.D.
    Note: See the PDF Version Soil organic carbon is the basis of sustainable agriculture and is important for chemical, physical and biological fertility. Consequently, carbon soil fertility could be improved more via sequestering. The role of microorganisms is important for carbon sequestration in soil compared to other factors. Thus, by increasing the activity of microorganisms we can increase carbon sequestration and soil fertility. Plantation forests were originally established in Sri Lanka to provide industrial timber and fuel wood. There are also other uses such as wind protection, bee keeping and oil extraction and moreover they provide invaluable ecosystem services. At present, sites available for reforestation in Sri Lanka are generally poor in nutrients and fertilizer application is required for better growth of seedlings. A novel approach of research at the IFS is the application of beneficial microbial consortia as biofilm biofertilizers for sustainable agriculture (Seneviratne et al., 2011). These are low cost and are eco-friendly. The shifts in composition and function of the microbial community in response to different stages of forest regeneration play an important role in determining rates of C changes (loss or gain) in the soil (Plante at al., 2005). Hence the long term goal of this study is to produce biofilm bio fertilizer for forest plantations to improve their yields. This would be more beneficial, less expensive and have no detrimental effects to the ecosystems. The biofilm bio fertilizer will be prepared using the microorganisms that have the capability of sequestering more carbon than the others. In this process, identification of the microorganisms and the factors affecting them is a crucial component. There are no studies conducted on this regard in Sri Lankan plantation forests yet. In the current study we investigated how the microbial biomass carbon (MBC) varies in Eucalyptus grandis forests in Sri Lanka with their age. Improved Carbon sequestration in forests would deliver better yields and would assist in minimizing climate change and support in obtaining foreign currency via carbon trading.
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    Microbial Deterioration of Stored Banana Varieties (Embul Kesel: Sour Banana and Kolikuttu: Silk Banana) and Determination of Their Best Storage Conditions
    (Uva Wellassa University of Sri Lanka, 2020) Prasadini, E.G.A.; Premetilake, M.M.S.N.
    The present study was focused to determine the best storage conditions and to assess microbial and nutritional variation of stored sour banana and silk banana during storage. Fresh and green samples of banana varieties were picked from a farm in the Badulla area. After surface sterilization, bananas were stored in four storage conditions; refrigerator (4°C), wet saw dust, dry sawdust, and room temperature which were served as treatments of the study. The content of protein, crude fat, sugar, moisture, and microbial counts was assessed in three-day until the bananas were over-ripened. Microorganisms were isolated and identification was done. Fusarium spp. and Aspergillus spp. were the dominating fungal species while Alcaligenes spp. and Xanthomonas spp. were the tentatively identified dominant bacteria in sour banana and silk banana respectively. But the best storage condition for both varieties was refrigeration (sour banana 13 days, silk banana 20 days). When considering the nutrient profile sour banana contained high protein percentage and low-fat percentage while silk banana contained low protein percentage and high-fat percentage throughout the ripening process. When ripening protein content has increased while fat content has decreased in both varieties. However, both moisture and sugar content increased and were almost similar in both varieties. Therefore, high protein and low-fat content could have led to faster ripening and microbial deterioration of sour banana. Protein and fat content play a major role in shelflife of studied banana varieties and the best storage condition for the selected varieties was refrigeration. Keywords: Sour Banana, Silk banana, Storage condition
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    Use of Trichoderma in Controlling Black Rot Disease and Increasing the Shelf Life of Carrots (Daucus carota L.)
    (Uva Wellassa University of Sri Lanka, 2021) Dias, H.O.N.; Premetilake, M.M.S.N.
    Carrot (Daucus carota L.) is one of the most widely grown and eaten vegetable but it is more vulnerable to many postharvest diseases such as black rot, which is caused by the fungus Alternaria radicina. Since there are many disadvantages of using fungicides,it is important to find an effective biocontrol method to control A. radicina. In the present study, the use of fungus Trichoderma asperellum in controlling A. radicina was investigated. Pure cultures of A. radicina which were isolated from infected carrot taproots were tested against T. asperellum using the dual culture technique. As the control A. radicina pure culture was used without T. asperellum. The A. radicina radial growth reduction percentage was found to be 58.33% . Then the effect of Trichoderma spp. in control of black rot was studied by making a small wound in healthy, organic, disinfected carrots and inoculated them with 1 mL of A. radicina conidial suspension. A 1 mL of T. asperellum (2.46×1010 spores per 1 mL) was added to the wounds after 48 hours. Positive control was the fungicide, Mancozeb and the negative control was sterilized distilled water. After 10 days of incubation at room temperature, T. asperellum reduced A. radicina by 72.63%. which is approximately similar to the effect of the positive control. T. asperellum had significantly (p<0.05) decreased disease occurrence and severity. In addition, inoculation of T. asperellum had greatly improved the minimum keeping time of average 13 days without characteristics symptoms which is seven days higher than the negative control. It can be conclude that, biological control of postharvest diseases by T. asperellum is an alternative to the use of fungicides and it could be a good solution for black rot disease in carrots. Keywords: Carrots; Biocontrol; Trichoderma asperellum; Black rot; Alternaria radicina