Browsing by Author "Senevirathna, T.C."

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    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).
  • No Thumbnail Available
    Item
    Solubility Enhancement of Eppawala Rock Phosphate Through Bioleaching
    (Uva Wellassa University of Sri Lanka, 2014) Senevirathna, T.C.
    Plants acquire phosphorus from soil solution as phosphate anion. It is the least mobile element in plant and soil contrary to other macronutrients. It precipitates in soil as orthophosphate or is adsorbed by Fe and Al oxides through legend exchange. Microorganisms have been active in the formation and decomposition of minerals in the earth's crust since soon after life on earth began. Phosphorus solubilizing bacteria play role in phosphorus nutrition by enhancing its availability to plants through release from inorganic and organic soil P pools by solubilization and mineralization. Principal mechanism in soil for mineral phosphate solubilization is lowering of soil pH by microbial production of organic acids and mineralization of organic P by acid phosphatases. In the present study two bacteria strains isolated from Eppawala Rock Phosphate (ERP) deposit and apply them for the ERP and HERP. The test of the relative efficiency of isolated strains is carried out by selecting the microorganisms which are capable of producing a halo/clear zone on PVK agar plate due to the production of organic acids into the surrounding medium. Out of four fungi and four bacteria two were selected as Phosphate Solubilizing Microorganisms (PSM). They were named as B1 and B2. According to the UV spectrophotometer results, B2 bacteria perform on HERP than B1 bacteria. B1 did not show any significant P solubilizing ability on ERP. But the B2 showed significant P content increment on ERP. When the P solubilizing abilities were compared between. ERP and HERP, B1 was the best candidate in the HERP containing PVK medium whereas the performance of B2 was the best in ERP, containing PVK medium. pH changing is almost similar in all the test samples. This result supports that the organic acid production by the secretion of microorganisms not the only reason for the P solubilization. It is influence with several other mechanisms like, the presence of interference by metal complexes in apatite to the process or growth of the organisms by impurities. Both CE controller sample and CH Controller samples P solubilizing rate is considerably lower than the other samples. That emphasis the microorganisms are directly contribute to increase the P solubilizing rate.