Browsing by Author "Peries, C.M."

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    Biocoagulation and Its Potential Application for Graphite Bioprocessing
    (Uva Wellassa University of Sri Lanka, 2013) Jayarathna, S.P.B.L.; Peries, C.M.; Henegamage, A.P.
    Sri Lanka is famous for Graphite industry since ancient times around the world. There are three major Graphite mines which are located in Kahatagaha, Bogala and Ragedara. Vein type graphite deposits in Sri Lanka are considered as a unique occurrence of graphite because of its high purity, extensive mineralization and restricted occurrence. Graphite with 95-99% of carbon and gangue minerals such as pyrite, chalcopyrite, calcite, biotite and feldspars are found in each structural type depending on the mode of occurrences and nature of graphite vein (Amarweeraet al., 2013). Hence, removal of impurities from the graphite can increase the economic value of graphite. Flotation cell is common in Graphite industry to upgrade its carbon grade by removing impurities and it can be used to upgrade over 80 % Graphite in Sri Lanka However, efficiency of the flotation cell separation is not effective for Graphite with small particle sizes (Karr et al., 1990). Biocoagulation is the promising method, practiced in all over the world for sorting of small sized mineral particles with the use of microorganisms (Kuyumcuet al., 2009). Therefore, this study is focused to increase the carbon recovery in Graphite through the separation of fine particles using the biocoagulation with microorganisms. Methodology Three different particle sizes (40µm, 53µm and 72µm) of graphite samples were obtained from Bogala and Kahatagaha mines. Isolation of fungi was carried out from the obtained samples using dilution plate techniques with Potato Dextrose Agar (PDA) medium. Pure cultures of the isolated fungi were obtained using single spore isolation technique with the same medium. Isolated pure fungi cultures were inoculated in to 20 ml of Potato Dextrose Broth (PDB) and incubated for 48 hours at 30 C. Then the pH values of the each fungi broth cultures were measured separately. Two grams of each different graphite samples with different particle sizes were mixed with the incubated PDB and kept with continuous mixing for the coagulation. After four days of incubation, the number of coagulates in each broth cultures was counted using the light microscope and the fungal broth culture (F3) which was given the highest coagulates number was selected for the further processing. In order to determine the carbon grade of the sample, coagulates of the selected broth culture were carefully separated out from the broth medium and washed with distilled water for three times. Then the particles with the coagulates were kept in a muffle furnace at 500 C for two hours in order to remove microbial biomass from graphite particles followed by keeping the samples again in muffle furnace at 960 C for further digestion. Initial and the final weights of the sample were measured to calculate the percentage of carbon recovery. Three replicates were maintained for each treatment and data were analyzed using ANOVA with the confidence level of 95% using MINITAB statistical software.
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    Development of Bioethanol from Water Hyacinth (Eichhornia crassipes) Using Cellulose Degrading Microbial Biofilm
    (Uva Wellassa University of Sri Lanka, 2019-02) Thakshika, G.; Peries, C.M.; Henegamage, A.P.
    Water hyacinth (Eichhornia crassipes), a persistent and invasive weed found in Sri Lanka that creates numerous problems to aquatic ecosystems. However, it is a promising candidate for bioethanol production due to its abundant availability, low cost and high yield. Currently, usage of lignocellulosic biomass is sustainable alternative to support the global demand for fossil fuels. Still, the conversion of cellulosic material to fermentable sugar is a rate-limiting step due to its highly resistant nature. Therefore, this study was focused to evaluate the efficiency of production of bioethanol from water hyacinth using cellulose degrading microbial biofilms. Microorganisms were isolated form soil sample obtained from a coir retting land in Kurunegala district and were inoculated on Carboxy Methyl Cellulose Agar to screen the most effective cellulolytic fungi and bacteria. One fungal (F2) and two bacterial isolates (B1, B3) were selected based on the cellulolytic activity. Biofilms were developed from the selected fungi and bacteria based on the high cellulolytic activity. The efficiency of the cellulolytic activity by the biofilms were evaluated using 3, 5 DNS assay. The selected biofilms were combined with 2 g of acid pre-treated water hyacinth and were kept nine days at room temperature for fermentation. Saccharomyces cerevisae served as the control. Bioethanol production was estimated by dichromate method and confirmed by FTIR analysis. Out of selected biofilms, F2B3 biofilm showed significantly higher bioethanol production (62.85 ppm, P< 0.05) than Saccharomyces cerevisae (59.81 ppm) after nine days’ of fermentation. Further, the yield of bioethanol obtained by F2B3 biofilm and Saccharomyces cerevisae from water hyacinth were 0.037% and 0.032% respectively. Therefore, there is a prospect to enhance the bioethanol production from water hyacinth using the effective biofilms.
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    Development of Biofilmed Biofertilizers for Bean (Phaseolus vulgaris)
    (Uva Wellassa University of Sri Lanka, 2010) Peries, C.M.; Seneviratne, G.
    Soil nitrogen deficiency may result in poor yields or failed crops and has traditionally been overcome by applying chemical fertilizers. But it is more expensive and can be harmful to the environment. The associations between fungi and root nodulating rhizobia as Fungal-Rhizobial Biofilms (FRBs) in leguminous plants is advantageous due to their ability to convert atmospheric nitrogen in to useful form in a process known as Biological Nitrogen Fixation (BNF). Although common bean (Phaseolus vulgaris) is the most frequently consumed legume worldwide, the yield is low and the plants have a low nitrogen fixing capacity compared to other legume plants. Therefore, this study describes the potential application of developed FRBs as Biofilmed Biofertilizers (BBs) to improve bean crop production. Biofilms were developed by combining bacteria and fungi isolated from the bean root nodules and rhizosphere. Then the developed biofilms were applied to the bean plants, which were grown in pots inside a greenhouse. These were compared with chemically fertilized plants. After 25 days from germination (early growth), dry weight of shoot, root and nodules of the plants were measured. Means of shoot, root and total plant dry weights of the treatments were compared using student's T-test. Three different types of fungi and bacteria were isolated from the bean root rhizosphere, according to their morphological differences. A successful biofilm formation was observed between selected fungi and bacteria isolated from the root rhizosphere. Among the treatments applied with BBs, those with Rhizobium showed better performance such as higher shoot and root dry weight with low variability and higher nodule dry weight during early growth stage. The results obtained by applying developed BBs to bean showed relatively low initial shoot growth compared with the chemical fertilizer applied bean plants due to competition between microbes of the BBs and the plant for nutrient acquisition. At harvest, the nodulation had just started. Plant biomass did not reflect the contribution of nodulation and biological nitrogen fixation, due to harvest in early growth. Therefore, further studies are necessary to evaluate the effect of BBs on bean at maturity. Key words: Biofilms, Biofilmed biofertilizers, Common bean
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    Development of Cost Effective Carrier Material for the Bio Fertilizer to Enhance Eppawala Phosphate Solubility
    (Uva Wellassa University of Sri Lanka, 2016) Rajhkumar, T.; Peries, C.M.; Cooray, J.T.
    Plants acquire phosphorus (P) from soil solution as phosphate anion. It is the least mobile element in plant and soil contrary to other macronutrients. Phosphorus solubilizing bacteria play role in phosphorus nutrition by enhancing its availability to plants. Bio fertilizers are inputs containing microorganisms which are capable of mobilizing, nutritive elements from non-usable form to usable form through biological processes. This study focused to develop a cost effective carrier material for the bio fertilizer to enhance the solubility of Eppawela phosphate. Eppawala Rock Phosphate samples were collected and microbial isolation was performed. Isolated microbial strains were inoculated on Pikovskaya's medium (PVK), a selective medium to screen Phosphorous Solubilizing Microorganisms. Thereafter, High-grade Eppawala Rock Phosphate (HERP) was mixed with carrier materials such as Kaolin, Fly ash and Glyceride were used because of containing high amount of plant nutrients and having the ability to increase the soil fertility. Kaolin and fly ash proportions were mixed in different proportions and apatite and gliricidia were maintained in constant in every treatment. Carrier material packets were prepared by mixing the broth cultures with sterile other ingredients. The P content was determined by the UV spectrophotometer at 400 nm. Two bacterial strains (B1 and B2) were selected as potential phosphate solubilizes on PVK agar medium. There was significant effect on carrier material type and the bacterial type for the P solubalization (p < 0.05). Both B1 and B2 bacterial types were shown high performance of the P solubalization with the addition of carrier material compare to the control. The most effective proportion of carrier material was Treatment 03 for the B1 bacterial types (Bacteria 1+ Rock Phosphate (40 g) + Gliricidia sepium (10 g) + Kaolin (30 g) + fly ash (20 g)) with the p value of 0.043 (p < 0.05). Both B1 and B2 bacterial types were shown highest P solubalization in 1S1 week.It can be concluded nutrient enriched carrier material can enhance the activity of phosphorous solubilizing bacteria for solubilizing phosphorus in HERP. Further, it can useful to develop the bio fertilizer with combining low water soluble HERP and the microbial population. Keywords: Bioleaching, Carrier material, Phosphorus solubilizing bacteria
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    Development of High Nutritious Value Added Bread from Composite Flour
    (Uva Wellassa University of Sri Lanka, 2013) Fernando, L.T.I.; Peries, C.M.; Henagamage, A.P.; Premathilake, M.M.S.N.
    Bread is a popular bakery product across the whole cross profile of the society, where all consumers like to consume bread alike, regardless of the level of income, education and other demographic characteristics (Lohano et al., 2010). Conventionally, flours used in bread making are made from cereals, mainly wheat (Nnabuk et al., 2012). Wheat is a foreign origin commodity and substantial amount of foreign exchange is required to import this food item, which is a real burden to the national coffer. Due to the drop in production of wheat internationally the future pricing of this product will be very uncertain and increasi ng prices will be forecasted (Piyasena et al., 1996). The government of Sri Lanka is also discouraging the consumption of wheat based products by mainly reducing the wheat flour usage by 20% and mixing with flour obtaining from various other sources could be used in order to save the massive amount of foreign exchange (Piyasena et al., 1996). In recent years, the demand to use novel sources as substitute for the wheat flour has increased to provide the consumers requirements. Replacement of wheat flour by other kinds of flour in bread making is economically important in Sri Lanka. There is a growing interest in using composite flour for bread making owing to some economic, social, and health reasons (Adeyemi and Idowu, 1990).The composite flours used were either binary or ternary mixtures of flours from some other starchy crops with or without wheat flour. Previous studies have given successful evidences for the substitution of 10 % cassava flour to wheat flour as the composite flour mixture for bread making process (Adeyemi and Idowu, 1990; Dhingra and Jood, 2004). Therefore, this study was focused to develop a high nutritious bread by partially substituting wheat flour with composite flour mixtures made out of Caryotaurens (Kithul) and Xanthosoma sagittifolium (Kiriala) flour. Methodology This study was designed to assess the quality of bread produced with composite flourobtained from wheat, X. sagittifolllium and C. urens. Matured X. sagittifolllium tubers and C. urens flour were obtained as raw materials and X. sagittifolllium tubers were further processed to obtain the flour. Six blends were prepared by homogenously mixing wheat, X. sagittifolllium and C. urens flour according to the percentage proportions, 100:0:0 (A), 50:50:0 (B), 50:0:50 (C), 50:40:10 (D), 50:30:20 (E), 50:20:30 (F), 50:10:40 (G) respectively. The dough mixtures with different blends were kept in a mold for 90 minutes at room temperature followed by baking in a pre-heated oven at 250°C for 30 minutes. Physical parameters such as loaf weight, loaf volume, specific volume and sensory attributes (i.e. crust and crumb color, taste, aroma, texture and overall acceptability) were evaluated by using 30 untrained panelists. Sensory data were statistically analyzed using Friedman Test with the confidence level of 95% using MINITAB 15. Proximate analysis and cost analysis were investigated for the selected bread sample in order to evaluate the nutritional quality and the total cost. Further, microbiological analysis (bacterial count, yeast and mold count) and shelf life analysis were performed for the selected best sample under the refrigerated condition and room temperature conditions separately.
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    Enhancement of Cellulolytic Activity through Biofilm Action for Bioethanol Production
    (Uva Wellassa University of Sri Lanka, 2018) Jayathilaka, M.G.L.W.; Henagamage, A.P.; Peries, C.M.; Seneviratne, G.
    Cellulosic biomass is a biopolymer with great potential for bioconversion to valueadded products. However, efficient degradation of cellulose is a problem in many industries including bioethanol production. Although a variety of microorganisms are capable of degrading cellulose, few of them produce significant quantities of enzyme fractions which hydrolyze cellulose to simple sugars. Extensive studies on bio-degradation by cellulolytic mixed microbial cultures would be beneficial in cellulosic biofuel production. Thus, this study was focused to evaluate the efficiency of cellulolytic activity of mono and mixed microbial cultures. Microbial isolations were carried out using soil samples obtained from a land at Kuliyapitiya, in Kurunegala district, Sri Lanka. They were streaked on Cellulose-Congo red Agar medium to screen for potential cellulolytic microorganisms. The selected microorganisms were inoculated on Carboxy Methyl Cellulose Agar medium to screen the most effective cellulolytic fungi and bacteria. Fungal-bacterial biofilms (FBB) were developed from the selected cellulolytic fungi and bacteria using Combine Carbon Broth. The efficiency of cellulolytic activity of the selected microbial combinations was evaluated using the production of reducing sugar through 3,5-Dinitro Salicylic acid after treating with cellulose powder. Two fungal (F1 and F2) and three bacterial isolates (B1, B2 and B3) were selected as the best cellulolytic microorganisms. Out of the selected cellulolytic microorganism, F2 and B I showed the significantly highest cellulolytic activities (P < 0.05). This mean reducing sugar level (113.90 ppm) was observed with the F2B1 combination after twenty three days of incubation. In addition, F2, B1 and B2 mono cultures showed significantly higher yield of reducing sugar than that of the other mono and mixed cultures, except F2B1. Thus, the selected FBB combination can be used to enhance the hydrolysis efficiency of cellulose for bioethanol production.
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    Enhancement of solubility of Eppawala Rock Phosphate through Bioleaching
    (Uva Wellassa University of Sri Lanka, 2015) Senevirathna, T.C.; Peries, C.M.; Cooray, J.T.
    Phosphorus (P) plays an indispensable biochemical role in photosynthesis, respiration, cell division and several other processes in the living plant (Grover, 2003). An inadequate supply of phosphorus in the early stages of plant growth reduces most of these physiological functions and ultimately reduces the crop productivity. Therefore, external applications of P fertilizers is necessary in terms of better crop production. Locally available P resources like Eppawala Rock Phosphate (ERP) deposits are now highly concerned due to the environmental effects and the high cost of imported P fertilizers. However, the ERP is considered as less applicable local P resource for short term cultivations due to the low solubility. Although chemical treatments are highly available to solubilize ERP, the cost of application is fairly high. In that sense, the inoculation of naturally existing P-solubilizing microorganisms is considered as a promising technique to solubilize P sources due to the low application cost and giving a thrust to economic development without disturbing ecological balance (Reyes et al., 2002). Thus, this study was focused on screening the P solubilizing microorganisms (PSM) from ERP deposit and apply them to enhance the solubility of ERP and High-Grade Eppawala Rock Phosphate (HERP). Methodology Powdered Rock Phosphate samples were collected from the rock phosphate stockpile of phosphate mine of Lanka Phosphate Limited, Eppawala. Microbial isolation were performed from the obtained Phosphate samples using standard microbiological techniques. Isolated microbial strains were inoculated on PVK medium, a selective medium to screen PSM. Thereafter, screened microbial strains were inoculated in PVK broth media containing either ERP or HERP separately. P content in each sample was determined using UV spectrophotometric method after 1 , 2 and 7 Result and Discussion Four bacterial strains and four fungal strains were initially isolated using the rock phosphate samples obtained from phosphate mine of Lanka Phosphate Limited, Eppawala, Sri Lanka. Out of them, two bacterial strains (B1 and B2) were selected as potential phosphate solubilizers based on the development of clear halo zone on PVK agar medium due to the P solubilization in the surrounding medium (Fig. 1 a and b).